Child restraint system

Abstract

Base (2) for a child restraint system (1), comprising a primary support section (101) projecting from an upper surface section (118) of the base (2) in a first direction (D1), wherein the primary support section (101) is configured to be releasably engaged by an engagement section (51, 52) of an inserted child seat (3) in a positive-locking manner to block movement of the child seat (3) in the first direction (D1), and is configured to rotatably support the child seat (3) about a pivot axis (R1) extending parallel to the first direction (D1), wherein a lateral outer surface (104) of the primary support section (101) has a circumferential recess (105) configured to receive the engagement section (51) of the child seat (3) to establish the positive-locking connection, thereby enablingto couple the child seat (3) with the primary support section (101) in several arbitrary angular orientations around the axis of rotation (R1).

Description

REGIONThe present disclosure relates to child restraint systems and components of child restraint systems, for example child seats such as an infant seat and a baby seat, support bases of child seats, in particular support bases, which are fixable to a vehicle seat and which may be an integral part of a child seat or which may be configured such that a child seat may be detachably coupled thereto. Further, the present disclosure relates to improvements in child seats.BACKGROUNDChild restraint systems having child seats and / or support structures such as bases mounted on a vehicle seat and serving as an interface between child seats and a vehicle seat are known in the art.Such systems must meet the highest safety standards while being easy for a user to operate.Known systems have the disadvantage that they are frequently difficult to operate. Moreover, there is still a need for improved security features.SUMMARYThe present disclosure relates to improvements of child restraint systems of the foregoing type. More particularly, the present disclosure relates to improvements of a base for releasably supporting a child seat and improvements of child seats releasably mountable to the base. Further, the present disclosure relates to improvements in child seats, such as baby seats and infant seats.It is an object to provide an improved child restraint system and / or components of a child restraint system, for example a base and / or a child seat such as an infant seat or a baby seat.The object is achieved by the configurations as set forth in the claims, aspects and exemplary configurations described herein. Advantageous further developments can be found in the dependent claims and in the following description.In some embodiments, a base for a child restraint system is provided. In some embodiments, the base may be configured to releasably couple a child seat to a vehicle seat. In some embodiments, the base may be configured as an integral part of a child seat, for example a rotatable child seat for a vehicle. In some embodiments, the base may be an integral part of a support structure, for example, a vehicle or a stroller.In some embodiments, a base may include a primary support portion. The primary support portion may protrude from an upper surface portion of the base in a first direction. The primary support portion may be configured to be detachably engaged by an engagement portion of an inserted child seat in a positive manner to block movement of the child seat in the first direction. The primary support portion may be configured to support the child seat rotatably about a rotation axis extending parallel to the first direction. The primary support portion may have a cone-like appearance. The primary support portion may have a free upper end portion with a narrower dimension compared to a lower end portion.In some embodiments, a lateral outer surface of the primary support portion is configured to receive the engagement portion of the child seat to establish the positive lock. In some embodiments, the primary support portion includes a circumferential recess configured to receive the engagement portion of the child seat, thereby allowing the child seat to be coupled, e.g., click, to the primary support portion at any number of angular position orientations about the rotational axis. The primary support portion may be configured to enable coupling of a child seat in any angular orientation. In some embodiments, the primary support portion may be configured to provide at least one angular deposition zone for a child seat in a range of more than 90° on each lateral side of the primary support portion. The range may be greater than 100°, for example substantially 110°, for example 112°. The aforementioned angular ranges may be provided around a rotation axis provided by the primary support portion, and may be symmetrical to a lateral direction perpendicular to the rotation axis so that half of the size of the angular range is provided on opposite sides of the lateral direction, respectively.In some embodiments, the primary support portion is configured to support the main weight of an assembled child seat. Additionally or alternatively, in some embodiments, the primary support portion may be configured to support the child seat at a predetermined distance from the upper surface portion of the base. Additionally or alternatively, in some embodiments, the primary support portion may be configured as a stationary support portion.In some embodiments, the primary support portion may include an upper portion supported by a pillar portion in an overhanging manner such that an overhanging portion of the upper portion is available for establishing the positive locking. In some embodiments, the circumferential recess is bounded by a bottom surface of the top portion and an outer surface of the pillar portion. In some embodiments, the pillar portion may be at least partially tapered toward the top portion.In some embodiments, the upper portion includes a layered structure including an upper layer and a lower layer supporting the upper layer. In some embodiments, the upper layer may be configured to come into sliding contact with a lower support surface of the child seat to be supported. In some embodiments, the lower layer has a higher stiffness than the upper layer. Additionally or alternatively, in some embodiments, the upper layer may include a low friction material configured to come into sliding contact with the child seat. Such a low friction material may include, for example, a synthetic material, for example, polyoxymethylene (POM). Additionally or alternatively, in some embodiments, the bottom layer may include a metal material. Additionally or alternatively, in some embodiments, the top layer may at least partially surround an outer edge region of the bottom layer. A bottom surface of the lower layer may be exposed or uncovered so that the engagement member of a mounted child seat may directly contact the lower layer. In some embodiments, the top layer has a sliding surface that extends around a recess. In some embodiments, the sliding surface may have a ring shape.In some embodiments, the recess is mechanically encoded so that another part, for example an insert such as a label, can be inserted into the recess only in proper alignment. The recess may be substantially circular. The recess may include a protrusion extending laterally inward into the recess. The mechanically coded recess can act as a positioning aid and the protrusion can act as a positioning portion. The protrusion may protrude into the recess in the radial direction.In some embodiments, the primary support portion may be configured as a hollow body. Such a hollow body may be closed at the top and define an accommodation space in its interior. In some embodiments, the accommodation space is configured to receive a portion of a tensioning mechanism and / or a sensor of a sensor assembly.In some embodiments, the base includes at least one secondary support portion. In some embodiments, the secondary support portion is radially spaced from the primary support portion. In some embodiments, the secondary support portion may be configured to receive a retaining portion of the child seat, wherein the retaining portion may be defined in or form part of a coupling interface of the child seat.In some embodiments, the secondary support portion may be configured to receive the retaining portion of the child seat by rotating the child seat about the rotation axis after the child seat is inserted on the primary support portion. The secondary support portion may be configured to engage the retaining portion. For example, the secondary support portion may be configured such that a retaining portion of the child seat may be lock-engaged with the secondary support portion by being inserted under the secondary support portion. This may prevent movement of the restraining portion relative to the base in the event of an accident scenario. Further, the secondary support portion may be configured such that an inserted child seat cannot be removed without rotating the same out of engagement with the secondary support portion.In some embodiments, the secondary support portion may be reinforced to resist high forces. For example, the secondary support portion may be steel reinforced. The secondary support portion may be made of or comprise sheet metal components.In some embodiments, the at least one secondary support portion is configured to limit tilting movement of the child seat about a second axis of rotation extending perpendicular to the axis of rotation.In some embodiments, the secondary support portion may be configured to reduce play between an inserted retaining portion of a child seat and the secondary support portion. By removing play, the seat can be held in a more rigid manner. Further, noise occurring due to vibration can be reduced.In some embodiments, at least one secondary support portion includes an urging member. The urging member may be a leaf spring. The urging member may be provided to apply an urging force to the retaining portion in a second direction opposite to the first direction when the retaining portion is accommodated in the secondary support portion.In some embodiments, an insertion geometry of at least one secondary support portion is mechanically encoded to block the child seat from being positioned in a predetermined orientation. Such a predetermined orientation may be a forward orientation of the child seat. In some embodiments, the secondary support portion may include a abutting portion configured to limit rotation of the child seat about the rotational axis toward a forward orientation. In the context of the present disclosure, a forward orientation or a forward orientation is intended to mean that the child seat is oriented such that the viewing direction of a seated child is in the direction of travel, for example in the direction of travel of the vehicle. In some embodiments, the abutting portion may be configured to contact a stop portion provided on the child seat.In some embodiments, the abutting portion includes abutting surfaces configured to contact stop portion surfaces. In some embodiments, the abutting surfaces are configured such that the stop portion is urged in a second direction opposite to the first direction when the stop portion is pressed against the abutting portion upon rotation of the child seat. The abutting surfaces may be oblique.The abutting portion may define the aforementioned settling zone. The abutting surfaces of a abutting portion may define an end of the angular range or the settling zone.In some embodiments, the at least one secondary support portion is configured such that rotation of the child seat about the rotational axis is automatically blocked when a rearward orientation is achieved upon rotating the child seat about the primary support portion. In the context of the present disclosure, a rearward orientation or a rearward orientation is intended to mean that the child seat is oriented such that the gaze direction of a seated child is opposite a direction of travel, for example a direction of travel corresponding to a direction of travel of the vehicle. Additionally or alternatively, in some embodiments, at least one secondary support portion may be configured such that the child seat is normally prevented from achieving the forward orientation and is rotatable to the forward orientation only upon actuation of an actuating member by a user. In some embodiments, the operating member is a releasing member of a locking mechanism for inhibiting rotation of the child seat about the rotation axis. In some embodiments, the locking mechanism is provided in the secondary support portion. The locking mechanism may be configured to engage with the retaining portion of the child seat.In some embodiments, the locking mechanism is operably configured by an actuation force applied thereto by the child seat. In some embodiments, the actuation force may be generated by converting a rotational force applied to the child seat into the actuation force.In some embodiments, the locking mechanism may include a locking member. The locking member may be movable between a locking position in which it can engage with the retaining portion of the child seat and a release position in which rotation of the child seat about the rotation axis is not blocked. In the release position, the locking component is released from the retaining portion. In some embodiments, the locking member may be biased by an urging member such that movement of the locking member toward the release position is possible against an urging force applied by the urging member. In some embodiments, the locking member may include a force receiving surface extending such that the actuation force may be generated by a force application surface on the child seat slidably contacting the force receiving surface when the child seat is rotated about the rotational axis.In some embodiments, the secondary support portion includes a support structure for blocking the inserted retaining portion from lifting from the base to prevent rotational movement of the child seat in the event of an accident. In some embodiments, the support structure includes a holder. The retainer may include a catch portion configured to receive the retaining portion of the child seat. The catching portion may have a hook shape. The catch portion may be made of metal or may include metal components.In some embodiments, the retainer is force-transmittingly coupled to a coupling portion configured to be engaged with a mounting structure in the vehicle seat. In some embodiments, the coupling portion may be provided on a coupling assembly. The coupling arrangement may comprise a connector, for example a coupling arm, such as an isofix arm.Additionally or alternatively, in some embodiments, the coupling portion on the base may be adjustably retained on the coupling portion to enable tensioning of the base to the vehicle seat.In some embodiments, the retainer may be force-transmittingly coupled to the coupling portion via a force transmission path including rigid force transmission members. The force transmission members may be metal force transmission members. In some embodiments, the force transmission path includes only metal force transmission members and all of the rigid force transmission members are metal force transmission members.In some embodiments, the force transmitting members may include a coupling portion supporting frame. The coupling portion support frame may include a connector support frame. The coupling portion support frame may include a U-shaped housing. The coupling portion may be supported on the coupling portion support frame.The force transmission members may include a coupling member, for example, a rod, for coupling the holder to the coupling portion support frame. In some embodiments, the holder is coupled to the coupling portion support frame only by a single coupling member. The holder may include a coupling portion. The coupling portion may have an opening to receive the coupling member, for example, the rod.In some embodiments, the support structure may include two brackets and two coupling portion support frames. Each coupling portion support frame may support a coupling portion, for example, the connector. The two coupling portion support frames may be coupled to each other by a single coupling portion such as the above-described coupling portion, for example, by a rod. The two holders may be coupled to the single coupling portion. The two coupling portion support frames may be laterally spaced apart from each other on a base.In some embodiments, a child seat is provided that is couplable to a base. The base may be a base as described above or as described below.In some embodiments, the child seat includes an interface portion releasably engageable with the primary support portion. In some embodiments, the interface portion includes a recess configured to receive the primary support portion. In particular, the recess may be configured to receive the primary support portion in the first direction. An insertion direction of the child seat may be a direction opposite to the first direction. Accordingly, when the child seat is inserted on the base, the primary support portion may be accommodated in the child seat. In some embodiments, the interface portion may include a support surface configured to contact a longitudinal end portion of the primary support portion.In some embodiments, the child seat may include a locking mechanism for releasably locking the child seat to the primary locking portion. The locking mechanism may include an engaging portion that is disposed to be movable radially into and out of the recess so as to be capable of engaging with the primary support portion, for example, with a circumferential recess of the primary support portion. In some embodiments, the locking mechanism may include an operating member for retracting the engagement portion.In some embodiments, an opening end portion of the recess may be defined by an inclined circumferential wall portion in which an outer diameter of the recess is reduced from an opening toward the support surface. In other words, the recess may include a chamfer portion that provides a centering function upon insertion of the child seat on the base and facilitates insertion of the child seat on the primary support portion.In some embodiments, the actuating member may be positioned on the child seat such that it is only accessible when the child seat is rotated to an unlocked orientation that is different from a forward or rearward orientation of the child seat on the base. In some embodiments, the operating member is provided at a lower side of the child seat. In some embodiments, the operating member is provided at a position of the child seat so as to be covered by the base when the child seat is in a forward or rearward orientation and is exposed only in the unlocking orientation. The operating member may be provided at a foot end of the child seat.In some embodiments, a child restraint system is disclosed that includes a base and a child seat. The base may be configured as described above or configured as described below with respect to other embodiments and modifications. The child seat may include one or more of the features described above and may additionally or alternatively include one or more of the features described below with respect to further embodiments and modifications.In some embodiments, a base may include a tensioning mechanism configured to generate a biasing force for urging the base toward the vehicle seat once the base is operatively connected to a mounting structure of the vehicle.In some embodiments, the tensioning mechanism is configured such that a user can generate the urging force by repeatedly reciprocating an operating member of the tensioning mechanism.In some embodiments, the base for a child restraint system may include a coupling portion for fixedly coupling the base to a mounting structure of the vehicle.In some embodiments, the base may include an anti-rebound portion configured to be contacted with a seat back of the vehicle seat to limit at least rotational movement of the base toward the seat back in a crash situation.In some embodiments, the base may include a tensioning mechanism configured to apply a pulling force to the coupling portion. The base may include connectors each having a coupling portion. The connectors and / or coupling portions may be connected to each other by means of a connecting portion, for example a strap or a rigid connector. The tensioning mechanism may be configured to apply a force to the connecting portion and / or to the connectors, for example a pulling force.In some embodiments, the base may include a tensioning mechanism for decreasing a distance between the anti-rebound portion and the coupling portion. In some embodiments, the tensioning mechanism is configured such that a user can reduce the distance by repeatedly reciprocating an actuating member.The tensioning mechanism may comprise an actuating member actuatable by a user. The actuation member may be force-transmittingly coupled to one or more coupling portions and / or connectors to couple a base to a mounting structure on a vehicle seat via a tension force transmission path.In some embodiments, the tensioning mechanism may include an actuation member and a display device configured to display to a user when the actuation member is ready for use for tensioning. In some embodiments, the display device is configured to provide a user with a visual and / or audible indication. In some embodiments, the display device is configured to move the operating member to a predetermined display position.In some embodiments, the actuation member may be movable between a stowed position and a deployed position to actuate the tensioning mechanism. The storage position may be a position in which the operation member is accommodated in or on the base, for example, such that it does not protrude beyond an upper surface portion of the base. The extended position may be a position in which the operating member protrudes beyond an upper surface portion of the base. For example, the deployed position may be a position in which the actuation member is positioned to extend at an angle from the base. In the storage position, the operating member may extend substantially horizontally. In the extended position, the actuation member may extend at an angle with respect to the horizontal direction. The predetermined display position may be an intermediate position between the storage position and the deployed position.In some embodiments, the base includes a recess in the upper surface portion that allows the actuating member to be engaged, for example, when provided in the stowed position.In some embodiments, the display device is configured to automatically move the operation member to the predetermined display position when a predetermined condition is satisfied. The predetermined condition may include a condition in which the coupling portion is engaged with the fixing structure. The predetermined condition may include a condition in which a distance between the coupling portion and the anti-rebound portion is reduced to a predetermined intermediate distance, for example, by pressing the base toward a seat back of the vehicle seat in a pressing direction, wherein a coupling portion is engaged with a mounting structure of the vehicle seat.In some embodiments, the display device may include two cooperation portions, for example, a toothed portion and a recessed portion. At least one of the two cooperating portions may be movable relative to the other and the cooperating portions may be configured to releasably engage when the predetermined display position is reached. In some embodiments, the two cooperation portions may be configured to restrict at least movement of the operating member out of and / or into the predetermined display position. In some embodiments, one cooperation portion of the two cooperation portions is provided on the operation member, and the other cooperation portion of the two cooperation portions is provided on a main body of the base.In some embodiments, the operating member is force-transmittingly coupled to the coupling portion by a ratchet mechanism. The ratchet mechanism may be configured to allow transmission of torque applied to the actuation member only in a clamping direction. In some embodiments, the ratchet mechanism includes a locking member configured to releasably lock the actuating member to an output member of the ratchet mechanism. The locking component may be a spring-loaded locking component. The output member may be an output shaft. When the operating member is locked to the output member, the operating member is integrally movable with the output member at least in the clamping direction. In some embodiments, the output member includes a gear fixed to the output member to be integrally rotatable with the output member.In some embodiments, the actuating member is a lever that is rotatable about a rotational axis. The lever may be a curved lever. The lever can be rotatably mounted at its two ends. The lever may have a U-shape. In some embodiments, the lever may extend around a primary support portion. In some embodiments, the lever is supported on opposite sides of the primary support portion. In some embodiments, the pivot axis of the lever extends in the transverse direction of the base.In some embodiments, the tensioning mechanism is configured to move the coupling portion relative to the anti-rebound portion. In some embodiments, the tensioning mechanism is configured to translate the coupling portion relative to the anti-rebound portion. In some embodiments, the tensioning mechanism is configured to translate the coupling portion in a longitudinal direction of movement.In some embodiments, the tensioning mechanism is configured to move the anti-rebound portion relative to the coupling portion. In some embodiments, the tensioning mechanism may be configured to move the anti-rebound portion translationally and / or rotationally relative to the coupling portion.In some embodiments, the coupling portion is part of a coupling assembly. In some embodiments, the coupling assembly includes two connectors, for example, coupling arms, optionally supported by a support structure and movable between an extended position and a retracted position. In some embodiments, the connectors, for example coupling arms, are coupled together by a connection device. In some embodiments, the connecting device is a rigid connecting member. In some embodiments, the two connectors are coupled to each other so that they are integrally or at least jointly movable, for example by applying a force to the connection device.In some embodiments, the coupling assembly is centrally driven and / or may include a driven portion that is force-transmittingly coupled to the connection device. In some embodiments, the driven portion may be force-transmittingly coupled to a force output member of the tensioning mechanism. In some embodiments, the driven portion may include a toothed portion. In some embodiments, the driven portion may include a rack. In some embodiments, the force output member may include a gear that engages the driven portion.In some embodiments, the tensioning mechanism and / or the ratchet mechanism may include a torque limiting mechanism. The torque limiting mechanism may be provided in the aforementioned tension force transmission path. The torque limiting mechanism may be configured to limit a transmittable torque to a predetermined maximum torque. In some embodiments, the operating member is power-transmittingly coupled to the coupling portion via the torque limiting mechanism.The torque limiting mechanism may include a first portion that is force-transmittingly coupled to the operating member. The torque limiting mechanism may include a second portion that is force-transmittingly coupled to the coupling portion and / or a connector. The first portion may be engageable with the second portion in a torque transmitting manner, for example, by tooth engagement. The first portion and / or the second portion may be movable into and out of engagement with the other portion. An urging member may bias at least one of the first portion and the second portion into engagement with the other portion of the two portions. The first portion and the second portion may be configured such that torque transmitted therebetween generates a biasing force on at least one of the first portion and the second portion in the releasing direction. When such a force exceeds a predetermined force applied by the urging member, the first portion and the second portion are released and torque transmission is interrupted.In some embodiments, the base includes a release mechanism. The release mechanism may be configured to release the coupling portion from the mounting structure and / or may be configured to release a tensioning mechanism and / or may be configured to release movement of the coupling portion relative to the anti-rebound portion. The tensioning mechanism may be a ratchet tensioning mechanism. The clamping mechanism may be a clamping mechanism as described above or as described further below. The tensioning mechanism may be configured to reduce a distance between an anti-rebound portion and the coupling portion.In some embodiments, the release mechanism includes at least one actuation portion. The operating portion may be provided on the base so as to be accessible only when a child seat is removed from the base.In some embodiments, the operation portion is provided on an upper surface portion of the base at a position covered by an inserted child seat. Additionally or alternatively, in some embodiments, the base may include a cover member movable between a cover position where the cover member covers the actuation portion and a release position where the actuation portion is accessible for actuation. In some embodiments, the cover member is configured to be moved to the cover position when a child seat is deployed on the base.In some embodiments, the release mechanism includes two actuation portions. In some embodiments, the release mechanism is configured such that releasing the base from the attachment structure is possible only by actuating both actuating portions, in particular by actuating both actuating portions simultaneously or successively.In some embodiments, the release mechanism is configured to release the coupling portion and the tensioning mechanism simultaneously. In some embodiments, the two operating portions may be provided on opposite sides of a primary support portion. In some embodiments, each actuating portion may include a lever.In some embodiments, the operating member may include a coupling portion for force-transmittingly coupling the operating member to the coupling portion. In some embodiments, the coupling portion may be coupled to an end portion of a power transmission member. The force transmission component can be a Bowden cable. The force transmission member may be adjustable to allow adjustment of force transmission from the actuation member to the coupling portion.In some embodiments, the release mechanism is configured such that upon actuation of the release mechanism, the tensioning mechanism is deactivated by transitioning the tensioning mechanism to a free-wheeling state.In some embodiments, the clamping mechanism includes an operating member that is force-transmittingly coupled to the coupling portion by a ratchet mechanism that allows torque applied to the operating member to be transmitted only in a clamping direction. In some embodiments, the release mechanism is configured to deactivate the ratchet mechanism by transitioning the ratchet mechanism to a free-wheeling state.In some embodiments, the ratchet mechanism includes a locking member configured to releasably lock the actuating member to an output member of the ratchet mechanism such that the output member is integrally movable with the actuating member. The locking component may be a spring-loaded locking component. The output member may be an output shaft. In some embodiments, the output member includes a gear fixed to the output member to be integrally rotatable with the output member.In some embodiments, the release mechanism may include a power transfer mechanism configured to transfer movement of the actuation portion into movement of the latch member in a release direction, thereby releasing latching between the actuation member and the output member. The movement of the actuating portion may be a rotational movement of the actuating portion in a third rotational direction.In some embodiments, the power transmission mechanism includes a power transmission member. The force transmitting member may be configured to receive an operation force from a force applying portion of the operation member. The force transmitting member may be configured to move toward the locking member upon receiving the operating force. In some embodiments, the force transmitting member has a force applying surface to contact a force receiving portion of the locking member. In some embodiments, the force application surface may be in the form of an outer surface of a truncated cone to allow interaction of the force receiving portion at different angular orientations of the actuation member.In some embodiments, the force transmitting member may be a sleeve extending about a rotational axis of the actuating member. In some embodiments, the force transmitting member is slidably provided on the output member.In some embodiments, the force transmitting member has a force receiving surface, and the force applying portion has a force applying surface contacting the force receiving surface. In some embodiments, the operating portion is configured to be rotatable about the rotational axis in a third rotational direction. In some embodiments, the force receiving surface and the force applying surface are configured such that the force transmitting member is displaceable in a displacement direction along the rotational axis by a wedge effect generated by a sliding contact between the force applying surface and the force receiving surface.In some embodiments, each actuating portion includes a lever. In some embodiments, the coupling portion and the force applying portion of each operating portion are integrally formed on the lever.In some embodiments, the coupling portion is configured to automatically move to an extended position when movement of the coupling portion relative to the anti-rebound portion is enabled by the release mechanism.In some embodiments, the coupling portion is biased by an urging member in a direction away from the anti-rebound portion. The urging member may be a coil spring.In some embodiments, the coupling portion may be part of a coupling assembly. In some embodiments, the coupling assembly may include at least one connector, for example a coupling arm, supported on a support structure and movable between an extended position and a retracted position. In some embodiments, at least one connector and the support structure are configured to be releasably lockable to lock the coupling portion at a plurality of different locking positions on the support structure. In some embodiments, at least one connector includes a locking portion and the support structure includes receiving portions. The receiving portions may be recesses. In some embodiments, the locking portion may be configured to be releasably engageable with the receiving portions. In some embodiments, the release mechanism is configured to release a latch between the connector and the support structure to allow movement of the coupling portion relative to the anti-rebound portion.In some embodiments, the coupling assembly includes two connectors supported by the support structure and each having a coupling portion. In some embodiments, the two connectors are coupled together by a connector. The connecting device can be a rigid connecting component. In some embodiments, the two connectors are coupled to each other so as to be integrally movable. In some embodiments, the urging member is configured and arranged to apply an urging force to the connection device.In some embodiments, a connector is provided for coupling a child restraint system to a vehicle seat. The connector may be a connector of the coupling assembly as described in other parts of this specification. The connector may be a coupling arm. The connector may be a coupling arm configured for an isofix system.In some embodiments, the connector includes a coupling portion provided at the first end portion and configured to be releasably locked to a mounting structure of a vehicle seat. The coupling portion may include one or more of the features as described herein in other parts of this specification. In some embodiments, the connector includes a locking portion spaced from the coupling portion in a longitudinal direction of the connector.In some embodiments, the locking portion is movably disposed between a locking position in which the locking portion protrudes from an outside of the connector and a releasing position in which the locking portion does not protrude from the side outside. For example, the locking portion may be configured to engage receiving portions of the support structure as previously described.In some embodiments, the locking portion is translationally movably disposed. In some embodiments, the locking portion is movable in a direction transverse to the longitudinal direction.In some embodiments, the locking portion is linearly movable between the release position and the locking position.In some embodiments, the locking portion is linearly movable in a direction perpendicular to the longitudinal direction of the connector.In some embodiments, the connector includes two locking portions, a first locking portion and a second locking portion. In some embodiments, the first locking portion includes a stop surface. In some embodiments, the stop surface of the first locking portion is oriented in the forward direction of the connector toward the coupling portion. In some embodiments, the second locking portion includes a stop surface. The stop surface of the second locking portion may be oriented in a rearward direction of the connector away from the coupling portion.In some embodiments, the second locking portion is operatively connected to the coupling portion such that the second locking portion is moved to the release position when the coupling portion is engaged with the attachment structure.In some embodiments, the connector includes a release portion for manually moving the second locking portion to the release position regardless of a coupling status of the coupling portion.In some embodiments, the releasing portion may be an operating portion of the force transmitting member. In some embodiments, the force transmitting member may be linearly movable along the longitudinal direction of the connector between a release position and an actuation position. In some embodiments, the force transmitting member may include a force applying portion configured to cooperate with the second locking portion such that the second locking portion is moved toward the release position when the force transmitting member is moved toward the actuation position.In some embodiments, the force transmitting member is disposed between the coupling portion and the second locking portion.In some embodiments, each locking portion is biased toward the locking position by an urging member. The urging member may be a spring.In some embodiments, two connectors may form a coupling arrangement. In some embodiments, a two connector coupling assembly is provided for a child restraint system. The coupling arrangement and / or the connectors may include features as described in other parts of this specification. The coupling arrangement may comprise two connectors. The coupling arrangement can further comprise a connecting device. The connecting device may rigidly couple the two connectors to each other so that the two connectors are integrally movable.In some embodiments, a base for a child restraint system is provided. The base may include features as described in other parts of this specification. In some embodiments, the base includes a support structure and a coupling assembly. The support structure may be configured as described in other parts of this specification. The coupling assembly may be supported on the support structure to be movable between an extended position and a retracted position. Furthermore, the coupling arrangement can be releasably lockable in at least one of the extended position and a retracted position by releasably locking the retaining structure and the coupling arrangement by means of the locking portion in a positive locking manner.In some embodiments, the first locking portion and the second locking portion are provided on or may form part of a first engagement member and a second engagement member, respectively. The first engagement component and the second engagement component can be formed identically. Accordingly, it is not necessary to produce two different parts.In some embodiments, the first locking portion and the second locking portion are configured to translate between the locking position and the release position. The first locking portion and the second locking portion may be mounted in the connectors to be translationally movable along a straight path.Each connector may include a housing. In some embodiments, the housing is formed by a first housing portion and a second housing portion. Together, the first housing portion and the second housing portion may form a hollow profile defining an inner space for accommodating parts of a mechanism for operating the coupling portion and for moving the first locking portion and the second locking portion. In some embodiments, the hollow profile formed by the first housing portion and the second housing portion may be closed at the rear side by a rear cap. The rear cap and the coupling portion may be provided on opposite sides of the connectors. The rear cap and the coupling portion may be provided on opposite longitudinal sides of the first housing portion and the second housing portion. The rear cap may include a cable guide that allows the cable to pass therethrough for connection to the internal mechanism of the coupling assembly.In some embodiments, the releasing portion for manually moving the second locking portion to the releasing position may be provided adjacent to the coupling portion on an upper side of the connectors. The release portion may be slidably supported on the connectors. The release portion may be operatively connected to the second locking portion. The release portion may be configured and arranged such that by displacing the release portion away from the coupling portion, the second locking portion is brought into the release position.In some embodiments, the second locking portion may be configured to block movement of the coupling portion in a retracting direction as long as the coupling portion is not blocked with the attachment structure. The release portion is configured to enable manual cancellation of this function and may be used to manually move the second locking portion to the release position.In some embodiments, the first locking portion and / or the second locking portion is / are biased by means of an urging member towards the locking position. The urging member may be a spring.In some embodiments, the first engagement member and the second engagement member may each include a force receiving portion. The force receiving portion may include a cylindrical portion protruding from a lateral side of the engagement members.The connector may include a first support portion configured to linearly guide the first engagement member. The first support portion may include a guide track formed as a straight slot extending in the vertical direction. The force receiving portion of the first engagement member may be configured to extend through the track and into a force applying portion provided in an operating member. In some embodiments, the force applying portion has an opening defined on the upper side by an oblique force applying surface. In some embodiments, the force application surface is inclined so as to cross a horizontal center plane of the connector at a position in front of the first engagement member, for example, at a position between the first engagement member and the coupling portion. In this way, a movement of the actuating member in the longitudinal direction of the connector can be transferred into a movement of the first engagement member in a direction perpendicular to the longitudinal direction of the connector along the guide track.In some embodiments, the operating member is arranged to be linearly movable along the longitudinal direction of the connector. In some embodiments, the operating member is configured to transmit an operating force to the first engagement member. In some embodiments, the actuation member is operatively connected to the release mechanism as described in other parts of the present description. In some embodiments, the actuation member is operatively connected to the coupling portion. In some embodiments, actuating the actuating member results in retracting the first locking member to the release position and unlocking the coupling portion. The actuating component can be operatively connected to the release mechanism by means of the force transmission component. The force transmission component can be a Bowden cable. In some embodiments, the actuation member may be operatively connected to the coupling portion of the actuation member of the release mechanism as described in other parts of this specification.In some embodiments, the child restraint system may include a display portion. In some embodiments, the display portion may be configured to provide centralized information about the status of the child restraint system. For example, centralized information about the mounting status of the child restraint system may be provided. In some embodiments, the display portion is configured to display the information in a spatial manner that allows a user to directly spatially determine locations of portions on the child restraint system to which the displayed information relates. In this way, spatial information and spatial relationships are easily understood by a user.In some embodiments, the display portion is configured to display the information on a map showing the child restraint system.For example, the display portion may display the information on a map showing a base of the child restraint system, for example, showing the entire base in a plan view or an outline view. In some embodiments, the information includes spatially related objects, facts, or processes, and the display portion is configured to graphically display the related objects, facts, or processes in their spatial relationships.In some embodiments, the display portion includes the map. For example, the display section may have the map in the form of a representation provided on the display section. In some embodiments, the display portion includes at least one indicator provided at a predetermined position on the map. The predetermined position of the map may directly correspond to a location on the basis.In some embodiments, the display portion includes two indicators each indicating a coupling status of a connector, for example, a coupling arm, of the base.In some embodiments, an indicator is configured to indicate a status of a load leg of the base. For example, at least one indicator may be configured to indicate whether a load leg is in a park or stowed position or in an extended / use position.In some embodiments, the display portion may include at least one indicator that displays an insertion status of the child seat on the basis.In some embodiments, a child restraint system may include two connectors, a first connector and a second connector each configured to be detachably lockable to a mounting structure of a vehicle, and a display portion configured to provide information about the mounting status of the connectors. The display portion may be configured to display at least four different lock states of the two connectors.In some embodiments, the child restraint system may include a first sensor provided in the first connector and a second sensor provided in the second connector. In some embodiments, each of such a first sensor in the first connector and such a second sensor in the second connector is configured and arranged to monitor a locking status of the connectors with a mounting structure on a vehicle seat. In some embodiments, the display portion is configured to display the aforementioned at least four different lock states of the two connectors.In some embodiments, the child restraint system may include a display portion configured to provide centralized information about the status of the child restraint system, and the display portion may include at least two lighting portions that display a predetermined status of the child restraint system. At least two of the illumination portions may be configured to be simultaneously illuminated by a single light source. The centralized information may include, for example, information about the mounting status of the child restraint system. Further, the display portion may include features as described herein in connection with other various possible configurations of display portions.In some embodiments, the display device includes a beam splitter for splitting and guiding emitted light from the light source to the illumination portions.In some embodiments, a seat detection sensor is provided for detecting the presence of an inserted child seat in a base for or a child restraint system. The base may be configured as described herein with respect to other configurations of the base. In some embodiments, the seat detection sensor may be provided on a primary support portion, for example a primary support portion as already described above or as described below in specific configurations and aspects.In some embodiments, the seat detection sensor may be provided in the primary support portion, for example, in an accommodation space inside the primary support portion or in an upper portion of the primary support portion.In some embodiments, the sensor is a magnetic sensor, for example a Hall sensor. The magnetic sensor may detect the presence of a magnet in a child seat correctly positioned on the base.In some embodiments, a child seat is provided that is mountable on a base. The child seat may have at least one sensor-detectable feature. The sensor detectable feature may be a magnet or may include a magnet. In some embodiments, the sensor detectable feature may be provided at a lower portion of the child seat. The lower portion may be, for example, a support portion defining a support surface of the child seat. The sensor detectable feature may be configured to trigger a seat detection sensor to detect the presence of the child seat on the base when the child seat is correctly mounted and / or aligned on the base. As described above, such a seat detection sensor may be provided in a primary support portion of the base.In some embodiments, the child seat includes two sensor detectable features provided on the lower portion of the child seat. In some embodiments, each of the two sensor detectable features comprises a magnet. In some embodiments, the two sensor detectable features are provided on opposite sides of a center of rotation of the child seat. Further, the two sensor detectable features may be disposed at an equal distance from the center of rotation of the child seat. In this way, it is possible to detect correct insertion of the child seat even if the child seat can be correctly mounted on the base in two different orientations. In each of these two different orientations, a single sensor provided on the base may be configured and arranged on the base such that it is possible to sense the two sensor detectable features on the child seat in each of the two orientations of the child seat.In some embodiments, a base for a child restraint system is provided. The base may include features as described in connection with other configurations and aspects of bases described herein. In some embodiments, the base includes a locking mechanism for blocking rotation of an inserted child seat about an axis of rotation. In some embodiments, the locking mechanism includes a locking member.The locking member may be movable between a locking position and a release position. In the locking position, the locking member is positioned to engage the retaining portion of a child seat. In the release position, the locking member is in a position in which it cannot engage with a retaining portion of the child seat, so that rotation about the rotational axis cannot be blocked by the locking member. In some embodiments, a sensor arrangement is provided that is configured to sense at least the presence of the locking member in the release position.In some embodiments, the sensor arrangement may be configured to additionally sense the presence of the locking member in the locking position.In some embodiments, the base includes a sensor detectable feature operatively connected to the locking member to be movable in response to movement of the locking member. The sensor detectable feature may be movable between a first position corresponding to a locking position of the locking member and a second position corresponding to a release position of the locking member. In some embodiments, the sensor detectable feature is disposed on the locking member so as to be integrally movable with the locking member. In some embodiments, the locking member may include a retainer for holding the sensor detectable feature.In some embodiments, the sensor assembly includes two sensors configured to sense the sensor detectable feature movably coupled to or provided on the latch member. In some embodiments, the sensor assembly includes two sensors configured to sense a single sensor detectable feature. In some embodiments, the sensor assembly is configured to detect a triggering sequence of the sensors by the detectable feature. In some embodiments, a positive lock signal is output when a predetermined triggering sequence of the sensors is detected.In some embodiments, the predetermined triggering sequence includes at least sensing the sensor detectable feature by a second sensor while the sensor detectable feature is still sensed by the first sensor and / or vice versa.In some embodiments, the sensor detectable feature may include a magnet and the sensors may be magnetic sensors, particularly Hall sensors.In some embodiments, the sensors are arranged to enable make-before-break sensing of the magnet.In some embodiments, the locking member is movable to a standby position in which the locking member is positioned in a fully extended position. In some embodiments, the sensors are positioned such that only one sensor detects the sensor detectable feature in the standby position. In some embodiments, the locking position is a position between the fully extended position and a retracted position. In some embodiments, the fully extended position and the retracted position are fixed end positions that limit a range of movement of the locking member.In some embodiments, the base may include a sensor assembly configured to sense proper support of the child seat on the base. Further, the sensor arrangement may be configured to detect a correct orientation of the child seat on the basis. If the correct support of the child seat and / or the correct orientation of the child seat are detected, a confirmation signal can be output.In some embodiments, the confirmation signal includes turning on a light source without changing colors of the light source.In some embodiments, the base may include a primary support portion, for example a primary support portion, as already described above. The primary support portion may be configured to support the child seat rotatably about a rotation axis. Further, the base may include a locking mechanism for locking rotation of the child seat about the rotation axis. The locking mechanism may include features as previously described or as described later in connection with other configurations and aspects. In some embodiments, the base includes a seat detection sensor configured to detect at least the presence of the child seat. In some embodiments, the seat detection sensor is configured to detect the presence and a predetermined allowable orientation of the child seat on the primary support portion.In some embodiments, the base includes a rotation lock sensor configured to detect whether a rotation of the child seat is locked.In some embodiments, the base may include a processing unit configured to receive signals from the seat detection sensor and the anti-rotation sensor and to output a signal indicating correct or incorrect mounting of the child seat based on the signals received from the seat detection sensor and the anti-rotation sensor.In some embodiments, the child restraint system may include a base mountable on the seat of a vehicle. The base may include a lower portion configured to contact a seat bottom of the seat.In some embodiments, the base may include a load leg for supporting the base on a vehicle floor portion. In some embodiments, the load leg is rotatably mounted to the base and movable between a stowed position and a deployed position. In the storage position, the load leg is folded against the lower portion. The stowage position can also be referred to as a parking position or non-use position of the load leg. The extended position can also be referred to as the use position. In the extended position, the load leg may be oriented to extend in an upward direction.In some embodiments, the stowage position of the load leg is detectable by a magnetic sensor provided on the base. In some embodiments, the extended position of the load leg is detectable by a magnetic sensor provided on the base. In some embodiments, the stowage position of the load leg and the deployed position of the load leg are both detectable by magnetic sensors provided on the base.In some embodiments, the magnetic sensor may be a proximity detection sensor. In some embodiments, the magnetic sensor may be a Hall sensor. In some embodiments, the magnetic sensor is provided at the lower portion.In some embodiments, the load leg has a free end portion configured to be contacted with the vehicle floor portion. The free end section can also be referred to as a foot section. The free end portion may comprise a magnet. The magnet may be provided in the free end portion on a side of the load leg that is oriented toward the lower portion when the load leg is in the storage position.In some embodiments, the magnetic sensor is covered by a magnetically attractable portion. For example, the magnetic sensor may be covered by a metal plate. In some embodiments, a magnetic attractive force between the magnet and the magnetically attractable portion is strong enough to hold the load leg in the storage position.In some embodiments, the base includes a lower portion configured to contact a seat bottom of the vehicle seat. In some embodiments, the base includes a load leg for supporting the base on a vehicle floor portion. In some embodiments, the load leg is rotatably mounted to the base and movable between a storage position in which the load leg is folded toward the lower portion and an extended position in which the load leg is capable of supporting the base against the vehicle floor portion.In some embodiments, the child restraint system is configured such that the load leg is releasably lockable in the storage position by magnetic attraction. For example, the base of or for a child restraint system may be configured such that the load leg is releasably lockable in the storage position by magnetic attraction.In some embodiments, the load leg includes a magnet. In some embodiments, the magnet is provided in a free end portion of the load leg. In some embodiments, the base includes a magnetically attractable member, for example, a steel plate.In some embodiments, a proximity magnetic sensor may be provided so as to be covered by the steel plate. In this way, the magnet has a dual function of generating an attractive force in cooperation with the steel plate and being detectable by the magnetic sensor.In some embodiments, a child restraint system may be provided that includes a base mountable on the seat of a vehicle. In some embodiments, the base may include a load leg. The load leg may be configured to support the base on a vehicle floor portion. The load leg may be rotatably mounted to the base at a coupling portion. The coupling portion may be provided at an upper end portion of the load leg. The load leg may be movable between a stowed position and an extended position in which the load leg is capable of supporting the base against the vehicle floor portion. The infant restraint system may be configured to sense the deployed position of the load leg using a contactless sensing arrangement.The contactless detection arrangement may include a magnetic sensor. The magnetic sensor may be a Hall sensor.In some embodiments, the load leg may include a magnet supported in the coupling portion to be integrally rotatable with the load leg. In some embodiments, the magnetic sensor and the magnet are arranged such that the magnet passes the magnetic sensor upon rotating the load leg to the extended position.The load leg may be coupled to the main body of the base by a pivot pin. The load leg may be rotatable about the pivot pin between the stowed position and the deployed position. The load leg may include a coupling portion. The coupling portion may be coupled to the main body of the base by the pivot pin. The load leg may include a magnet supported in the coupling portion to be integrally rotatable with the load leg.The magnetic sensor and the magnet may be arranged such that the magnet passes the magnetic sensor upon rotating the load leg to the extended position. The distance between the pivot pin and the magnetic sensor may be greater than the distance between the pivot pin and the magnet. In some embodiments, the magnet is moved into a region between the pivot pin and the magnetic sensor when the load leg is rotated to the extended position. The magnet can be held on the load leg by a magnet holder. The magnet may be held in a central portion of the coupling portion of the load leg.In some embodiments, a child seat may include a support structure and a seat structure supported on the support structure. The seat structure may include a seat bottom and a seat back. The seat structure may be transitionably configured between a seat configuration and a reclining configuration.In some embodiments, the seat back is configured to be rotatable about a fixed axis of rotation relative to the support structure. For example, the seat back may be rotatably coupled to the support structure via a first rotary connector, the first rotary connector defining the fixed pivot axis. The pivot connector may be a pivot pin.In some embodiments, the seat bottom may be configured to be rotatable about a movable axis of rotation. For example, the seat bottom may be configured to be rotatable about a second rotary connector that is routed along a predetermined path. When the seat structure is transferred between the seat configuration and the reclining configuration, the movable rotational axis can be moved relative to the supporting structure along the predetermined path.In some embodiments, the predetermined path is configured such that, when the seat structure is transferred between the seat configuration and the reclining configuration, the movable rotational axis is at least temporarily moved in an upward direction relative to the support structure.In some embodiments, the predetermined path is a curved path. In some embodiments, the predetermined path is a circular path.In some embodiments, the second rotary connector is supported on the support structure by means of a lever. The lever may be coupled to the support structure by means of a third rotary connector. In some embodiments, the third rotary connector couples the lever to the support structure at a position below the second rotary connector. In some embodiments, the lever is pendulously attached to the support structure. In some embodiments, the lever is attached to the support structure such that an end portion of the lever is attached to the support structure at a position above the second rotary connector.In some embodiments, the axes of rotation extend parallel to each other.In some embodiments, the seat bottom is hingedly coupled to the seat back by a fourth pivot connector. The fourth pivot connector may couple the seat bottom and the seat back at a distance from a lower seat surface on the seat bottom and at a distance from a backrest surface of the seat back. In some embodiments, the clearance is configured such that the fourth pivot connector is substantially at a natural hip joint level of a seated child.In some embodiments, the second pivot connector may be coupled to the seat bottom at a central portion of the seat bottom, for example substantially midway between a front end of the seat bottom and a rear end of the seat bottom. In some embodiments, the seat bottom may be hingedly coupled to the seat back at a rear end portion thereof.In some embodiments, an operation portion configured to receive a pulling force applied thereto by a user is provided at a lower portion of the seat bottom. In some embodiments, the actuation portion may be configured and arranged such that when the seat structure is in the seat configuration, a pulling force applied thereto acts in a pulling direction that extends substantially perpendicular to the movable rotational axis and substantially tangential to the predetermined path.In some embodiments, a child seat may include an interface portion for locking the child seat to a base fixedly mountable to a vehicle seat, such as an interface portion and a base, as described in other parts of this specification. The interface portion may be provided on the support structure of the child seat. Further, a seat structure may be supported on the support structure and configured to be transitionable between a seat configuration and a reclining configuration. The seat structure may be configured as described in other parts of this specification, for example.In some embodiments, the child seat is configured such that the operability between the seat configuration and the reclining configuration is suspended when the interface portion is supported on the base and the child seat is oriented in a predetermined direction, for example, a forward direction or a rearward direction. The predetermined direction may generally be a direction in which safe transport of a seated child is possible. In other words, the predetermined direction may be a direction in which the child seat needs to be aligned during the travel of the vehicle in which the child seat is mounted.In some embodiments, the child seat may include a locking mechanism for locking the seat structure in the seat configuration and the reclining configuration. In some embodiments, the locking mechanism includes an operating member for temporarily unlocking the locking mechanism. In some embodiments, the child seat is configured such that unlocking of the locking mechanism is blocked when the interface portion is supported on the base and the child seat is oriented in the predetermined direction, for example, in a predefined driving direction including the forward direction and / or the rearward direction.In some embodiments, the operating member is provided on the child seat so as not to be accessible to a user when the interface portion is supported on the base and / or the child seat is oriented in the predetermined direction, for example, a forward direction or a rearward direction.In some embodiments, the interface portion includes a retaining portion to be received in a secondary support portion of the base when the child seat is supported on the base and / or oriented in the predetermined direction. The secondary support portion may be configured as described in other parts of this specification. The interface portion may also be configured as described in other parts of the specification.In some embodiments, the operating member is provided on the child seat adjacent to the retaining portion. In some embodiments, the operating member is provided on the child seat adjacent to the front retaining portion. In some embodiments, the operating member is provided at a predetermined position above the retaining portion. In some embodiments, the operating member is provided to be at least partially covered by a portion of the base when the child seat is supported on the base and oriented in the predetermined direction. For example, the operating member may be covered by a portion of the secondary support portion as described herein in other parts of this specification.In some embodiments, the child seat includes a seat bottom and a seat back. In some embodiments, the operating member is provided at a lower front end portion of the seat bottom. In this way, the operating member is accessible to a user from a front end of the child seat.In some embodiments, a child restraint system is provided. The child restraint system may include a child seat as described above and a base mountable to the seat of a vehicle and configured to support the child seat. The child seat may include an interface portion that is releasably couplable to the base. The interface portion may be configured as described herein in other parts of this specification.In some embodiments, the child seat includes a locking mechanism for locking the seat structure in the seat configuration and the reclining configuration. In some embodiments, the locking mechanism includes an operating member for temporarily unlocking the locking mechanism. In some embodiments, the child seat and the base are configured such that unlocking of the locking mechanism is blocked when the interface portion is supported on the base and the child seat is oriented in a predetermined direction, for example, a forward direction or a rearward direction.In some embodiments, the child seat includes at least one restraining portion. The base may include at least one secondary support portion configured to receive the retaining portion of the child seat, for example, by rotating the child seat about a rotational axis. In some embodiments, the secondary support portion is configured such that the operation member on the child seat is covered by a portion of the secondary support portion. Such a portion of the secondary support portion may be a portion of the secondary support portion that protrudes into a space defined by an upper portion of the retaining portion and a lower front end portion of the seat bottom.In some embodiments, a child seat is provided with a support structure, a seat structure configured to be transferable between a seat configuration and a reclining configuration, and a locking mechanism for locking the seat structure in the seat configuration and the reclining configuration. The locking mechanism includes an operating member for temporarily unlocking the locking mechanism. Further, the operating member is provided at a lower front end portion of the seat bottom. The support structure, the seat structure, and the locking mechanism may be configured as described herein in other parts of this specification.In some embodiments, a locking mechanism is provided for locking the seat structure in the seat configuration and / or the reclining configuration. Such a locking mechanism may include or be arranged as described herein in other parts of this specification. The latch mechanism may be configured to be used in conjunction with a seat structure supported on a support structure, particularly such that a seat back of the seat structure is configured to be rotatable about a fixed rotational axis defined by a first rotational connector. The locking mechanism may be configured to engage between the seat structure and the support structure in a direction transverse to the fixed axis of rotation.In some embodiments, the locking mechanism is configured to engage in a radial direction with respect to the fixed axis of rotation.In some embodiments, the locking mechanism includes an engagement portion configured to move between a locking position and an unlocking position. In some embodiments, the engagement portion may be provided on the seat back. In some embodiments, the engagement portion may be arranged to be linearly movable, for example linearly movable in a radial direction with respect to the fixed rotation axis or parallel to the radial direction, for example perpendicular to the fixed rotation axis and optionally offset from the fixed rotation axis. In some embodiments, the engagement portion may be movably disposed substantially perpendicular to a back surface portion of the seat back. In some embodiments, the engagement portion is configured to move in a direction that includes a rearward direction component and a downward direction component.In some embodiments, the support structure includes at least two recesses for receiving the engagement portion. In some embodiments, the locking mechanism includes an actuation member operatively connected to the engagement portion. The operating member may be provided on the seat bottom. The operating member may be an operating member as described in other parts of this specification.In some embodiments, a child seat may be provided that includes a belt receiving portion. The belt receiving portion may be configured to receive a seatbelt portion of a vehicle seat for mounting the child seat to the vehicle seat. In some embodiments, the child seat includes a blocking portion configured to be moved between a blocking position and a release position. In the blocking position, an insertion of the belt section into the belt receiving section is blocked. In the release position, insertion of the belt portion into the belt receiving portion is permitted. In some embodiments, the blocking portion is configured to at least partially surround a wall portion of the belt receiving portion when the blocking portion is positioned in the blocking position.In some embodiments, the blocking portion includes an accommodation recess for accommodating the wall portion.In some embodiments, the recess is provided in a free end portion of the blocking member.In some embodiments, the free end portion has a stepped configuration. In some embodiments, the free end portion may have an L-shape.In some embodiments, the belt receiving portion includes an insertion portion and an accommodation portion. In some embodiments, the accommodation area may be configured to support an inserted strap portion across its entire width. In some embodiments, a dimension of the insertion portion is smaller than the dimension of the accommodation portion. In some embodiments, the blocking portion is configured and arranged to extend partially through the accommodation area into the insertion area when positioned in the blocking position.In some embodiments, the blocking portion is configured to protrude at least partially from below into the belt receiving portion when positioned in the blocking position.In some embodiments, a child seat includes a seat structure having a seat bottom and a seat back. The seat structure may be transitionably configured between a seat configuration and a reclining configuration. The blocking portion may be operatively connected to the seat structure. In particular, the blocking portion may be operatively connected to the seat structure such that the blocking portion is moved into the blocking position when the seat structure is transferred into the reclining configuration and is moved into the release position when the seat structure is transferred into the seat configuration.In some embodiments, the seat back includes a force applying portion and the blocking portion includes a force receiving portion. The force receiving portion may be coupled to the force applying portion. For example, the force receiving portion may be slidably held on the force applying portion. The blocking portion may be guided along a predetermined path. For example, the blocking portion may be guided along a straight path or a curved path. In some embodiments, the predetermined path may extend in an upward direction, for example, in a vertical upward direction. In some embodiments, the predetermined path may be defined in a support structure of the child seat. For example, a slot may be provided in the support structure to define the predetermined path. In some embodiments, the support structure includes the strap receiving portion. In some embodiments, the support structure is configured to rotatably support at least the seat back. In some embodiments, the force applying portion includes a slot and the force receiving portion is slidably received in the slot.In some embodiments, a child seat may include a carrying handle. The child seat may be a child seat as described herein in other parts of the specification. In particular, the child seat may be a child seat for a baby. The support handle is configured to support the child seat.In some embodiments, the support handle includes a primary handle portion configured to support the child seat with a single hand. The primary grip portion may extend in a first direction, for example, in a horizontal direction of the child seat.In some embodiments, the carrying handle includes two special secondary handle portions configured to carry the child seat with both hands. The two special secondary handle portions may extend in a second direction, for example transverse to the first direction in which the primary handle portion may extend as described above.In some embodiments, the secondary grip portions are provided on the carrying handle so as to be disposed at the same level. In some embodiments, the support handle has a U-shape with a base portion and two leg portions extending from the base portion. In some embodiments, free end portions of the leg portions are coupled to a support structure. Each leg portion may include one of the secondary handle portions.In some embodiments, the secondary handle portions include a shape-deviation portion in a surface of the carrying handle. The shape-deviation portion may have a local shape deviation that prevents the carrying handle from slipping by a user's hand when the user carries the child seat using the secondary grip portions. The shape-deviation portion may include a protrusion that delimits an upper portion of a grip region. The shape-deviation portion may have an uneven surface formed by, for example, corrugations, grooves and / or notches.In some embodiments, the secondary handle portions include a material deviation portion in a surface of the carrying handle. The material deviation portion may be configured to increase friction between the hand of a user and the carrying handle, and may include a rubber material.In some embodiments, the child seat may include a locking mechanism for releasably locking the child seat to a coupling interface of a support unit, for example a base for supporting the child seat on a vehicle seat or a frame of a carrier, for example a baby carriage. The locking mechanism may include an operating member for temporarily unlocking the locking mechanism. The secondary handle portions of the carrying handle are positioned on the carrying handle such that a user can manipulate the operating member with a hand just gripping the secondary handle portion. In some embodiments, the operating member and the carrying handle are configured such that the operating member is manually operable by a user while the user grips the carrying handle with both hands.In some embodiments, the support handle is rotatably disposed between a support position and a non-support position. The secondary handle portions may be disposed on the carrying handle such that a user may manipulate the manipulation members with the thumb of a hand while gripping the secondary handle portion with the fingers of the hand when the carrying handle is in the carrying position. In some embodiments, the secondary handle portions are disposed on the support handle such that adjacent operating members or operating portions of the operating members are positioned at the same level as the secondary handle portions when the support handle is in the support position.In some embodiments, the child seat may include a seat structure. In some embodiments, the seat structure may include a lower portion and a backrest portion. In some embodiments, the child seat may be configured as an infant seat.In some embodiments, the child seat may include a strap assembly. The strap assembly is configured to retain a seated child in the child seat. The strap assembly may include a shoulder strap for restraining a seated child. The belt assembly may include a buckle component coupled to the shoulder belt so as to be movable along the shoulder belt. The buckle component may be configured to engage a receiver coupled to the lower portion in an area that allows the receiver to be placed between legs of a seated child.In some embodiments, the child seat may include a headrest assembly for supporting the head of a seated child. The head restraint can be adjustable in height. The headrest arrangement may comprise a supporting structure. The headrest assembly may include a headrest portion. The support structure may be configured to support the headrest portion. The headrest portion is configured to support the head of a child, and is disposed between the support structure and the head of a seated child. The headrest portion may be made of a material having a lower rigidity compared to the material of the support structure. For example, the headrest portion may include or be made of a polyphenylene ether (PPE) or an expanded polypropylene material (EPP). Accordingly, the headrest assembly may include at least two members including the support structure and the headrest portion.The support structure may be made of a hard plastic material. The support structure may provide a reinforcement for the material of the headrest portion supported thereon. The headrest portion may be integrally formed of a single material. The support structure may comprise or be made of polypropylene material (PP). The support structure may comprise a reinforcing structure. The reinforcing structure may include ribs. The support structure may have a coupling portion. The coupling portion may be configured to be coupled to the backrest of a child seat. The coupling portion may include a belt opening for passing a shoulder belt of a belt assembly. The coupling portion may be configured and arranged to support the support structure together with the headrest portion at a predetermined distance from the backrest portion.The backrest portion may include a right shoulder support portion and the left shoulder support portion. At an upper portion of each of the right shoulder support portion and the left shoulder support portion, a headrest may be provided. The coupling portion and the support structure are configured such that a rear side and / or an outer side of the support structure is held at a predetermined distance from the headrest contact surface. The headrest contact surface provides a support surface on the backrest portion of the child seat. More specifically, in the event of an impact, forces acting on the child seat may force the headrest to move toward and contact the backrest portion at the headrest contact surface.An outer support surface may be provided on an outer side of the support structure configured to contact the headrest contact surface. The outer support surface may extend from a side head support portion of the headrest assembly to a rear portion of the headrest assembly. The outer support surface and the headrest contact surface may be configured to extend substantially parallel to each other. Accordingly, in some configurations, a distance between the outer support surface and the headrest contact surface along the extension directions of the respective surfaces may be substantially constant over at least a predetermined range. In this way, a proper support of the support surface on the backrest of the child seat is provided in the event of an impact. Compared to adjacent areas on the shoulder support portions of the child seat, the headrest contact surface may be provided as a protrusion. In other words, the headrest contact surface may be provided at a portion of the seat back that further extends into the seat interior to assist movement of the headrest resulting from a side impact.In some embodiments, the child seat is configured such that the shoulder belt portion of the belt assembly is temporarily attachable to the headrest assembly.In some embodiments, the child seat is configured such that the shoulder strap portion is attachable to the headrest assembly by magnetic attraction.In some embodiments, the headrest arrangement comprises a support structure, for example a support structure as already described above, and a cover component, for example a cover component made of fabric. In some embodiments, the support structure may include a magnet. In some embodiments, the cover member may include a magnet. In some embodiments, the headrest portion may include a magnet. In some embodiments, the magnet is provided at a front portion of the headrest assembly. In some embodiments, the magnet is provided on a side head support portion of the headrest assembly. For example, the magnet can be provided on an inner side of the headrest arrangement, for example on or in inner supporting surfaces. The magnet may be provided at an outer side of the front portion of the headrest assembly, for example, in an outer side portion at a front end portion of the side head support portion. In some embodiments, the magnet is provided at the bottom of the front portion of the headrest assembly. In some embodiments, each lateral head support portion may include a magnet on an outer side. In some embodiments, the magnet is disposed in a support structure of the headrest assembly, for example, at a front end portion of the support structure provided in the side head support portions. In some embodiments, the support structure may include a holding portion for accommodating the magnet. In some embodiments, the holding portion includes a recess for receiving the magnet. In some embodiments, the retaining portion is integrally formed in the support structure of the headrest assembly.In some embodiments, the shoulder belt portion includes a magnetically attractable portion. Such a magnetically attractable portion may be provided in the shoulder belt portion, for example, sewn into the shoulder belt portion. The magnetically attractable portion may be a steel insert. The magnetically attractable portion may alternatively be provided on a separate part attached to the shoulder belt.In some embodiments, the shoulder belt portion includes a buckle component. In other words, a buckle component may be provided on the shoulder belt. Such a buckle component may be movably provided on the shoulder belt and may be movable toward the shoulder belt portion to be temporarily fastened to the headrest assembly. The buckle component may include a buckle tongue. The buckle tongue may also be referred to as a latch because the buckle tongue serves to fixedly couple the buckle component to a receiver provided at the lower portion of the child seat in an area between legs of a seated child. In some embodiments, the buckle tongue forms the magnetically attractable portion. Accordingly, the buckle component may be retained on the headrest assembly by placing the buckle tongue in an effective area of the magnet provided in the headrest assembly. The buckle tongue may be made of steel.In some embodiments, a child seat may include a first interface portion and a second interface portion. The child seat may include features as described herein in other parts of this specification. The first interface portion may be configured to be releasably engageable with a first type of coupling interface. The first type of coupling interface may be a coupling interface provided on a child carrier such as a baby carriage. For example, the coupling interface may be provided on a stroller frame. The second interface portion may be releasably engageable with a second type of coupling interface. The second type of coupling interface may include a coupling interface of a base configured to be attached to a vehicle seat. The second interface portion may be an interface portion configured to be coupled to the primary support portion as described herein in other parts of the specification. The second type of coupling interface may include the primary support portion as described herein in other parts of this specification.In some embodiments, the child seat includes an actuation mechanism configured to actuate the first interface portion and the second interface portion simultaneously. The actuation mechanism may be configured to actuate the first interface portion and the second interface portion simultaneously to transition the interface portions to a release state. The release state may be a state in which the interface portions are in an unlock state.In some embodiments, the first interface portion includes a rotary lock mechanism. In the present disclosure, the rotary lock mechanism is to be understood as a lock mechanism in which locking and unlocking are established by a rotational movement. In some embodiments, the second interface portion includes a translation lock mechanism. In the present disclosure, the translation locking mechanism is to be understood as a locking mechanism in which locking and unlocking are established by translation movement.In some embodiments, the actuation mechanism is configured to translate a rotational input force into a rotational movement in the rotational locking mechanism and a translational movement in the translational locking mechanism.In some embodiments, the rotary locking mechanism includes a rotatably movable locking member. In some embodiments, the rotatably movable locking member may include an engagement portion. In some embodiments, the engagement portion may include a hook. In some embodiments, the rotatably movable locking member includes a force receiving portion for receiving an operating force. In some embodiments, the rotatably movable locking member may be configured as a lever. In some embodiments, the lever may be rotatably mounted to the child seat via a rotary connector. In some embodiments, the rotary connector may define a lever rotation axis. In some embodiments, the engagement portion and the force receiving portion may be disposed on opposite sides of the rotary connector. In some embodiments, the force receiving portion may be configured for sliding contact with a force applying portion. In some embodiments, the force receiving portion may be configured to receive a restoring force from a restoring spring. In some embodiments, the force receiving portion on one side may be configured for sliding contact with a force applying portion and / or configured to receive a restoring force from a restoring spring on an opposite side.In some embodiments, the translation locking mechanism includes a translationally movable engagement portion. In some embodiments, the translationally movable engagement portion may be or include a locking member. In some embodiments, the engagement portion may be radially movably disposed into and out of a recess of the second interface portion. In some embodiments, the recess may be provided in a bottom portion of the second interface portion. In some embodiments, the recess may extend in a first direction extending in a direction opposite to an insertion direction of the child seat on the second type of coupling interface. In some embodiments, the recess may be configured to receive the primary support portion protruding from a base in the first direction. The primary support portion and / or the base and / or the engagement portion may be configured as described in other parts of this specification.In some embodiments, the actuation mechanism includes an actuation member. The operating member may be force-transmittingly coupled to the first interface portion. The operating member may be force-transmittingly coupled to the rotatably movable locking member. In some embodiments, the actuating member may be force-transmittingly coupled to the second interface portion. In some embodiments, the operating member may be force-transmittingly coupled to an engagement portion of the second interface portion. The engagement portion of the second interface portion can be a locking component or can comprise this. In some embodiments, the actuating member is force-transmittingly coupled to the first interface portion and the second interface portion. In some embodiments, the actuating member is force-transmittingly coupled to the rotatably movable locking member and to the translationally movable coupling member.In some embodiments, the actuating member is force-transmittingly coupled to the second interface portion via the force transmitting member. Accordingly, the operation mechanism may include the power transmission member. In some embodiments, the force transmitting member may be configured to transmit a tensile force to the second interface portion. In some embodiments, the force transmitting member may be a flat member. In some embodiments, the flat member may have a band-like configuration. In some embodiments, the flat member may have a substantially rectangular cross-section. In some embodiments, the flat member may be configured to transmit only a tensile force to the second interface portion. In some embodiments, the flat member cannot transmit a pressing force to the second interface portion.In some embodiments, the force transmitting member is coupled to the engaging portion at at least two positions. In some embodiments, the force transmitting member is coupled to the engaging portion at laterally opposite sides of the engaging portion such that a total force applied to the force transmitting member is distributed to at least two of the at least two positions.In some embodiments, the force transmitting member may include a branch end portion. In some embodiments, each force transmitting member has a branch end portion. In some embodiments, the branch end portion includes a first branch portion and a second branch portion. The first branch portion may be coupled to the engagement portion at a first position, and the second branch portion may be coupled to the same engagement portion at a second position. In some embodiments, the first position and the second position may be offset from each other in a direction perpendicular to a moving direction of the engagement portion. In some embodiments, the first position and the second position may be laterally offset from each other in a direction perpendicular to a moving direction of the engagement portion. In some embodiments, the branch end portion may be formed as a one-piece part, for example, of plastic or metal. In some embodiments, the branch end portion may be coupled to a single engagement portion. In some embodiments, the branch end portion forms a Y-shaped branch. The Y-shaped branch may be configured such that the first branch portion and the second branch portion extend substantially symmetrically from an end portion of a central portion.In some embodiments, the force transmitting member is supported on a support structure of the child seat. In some embodiments, the force transmitting member is supported on only one side. In some embodiments, the force transmitting member is slidably supported on the support structure. In some embodiments, the force transmitting member is slidably supported on the support structure by surface contact with one or more support portions provided on the support structure. In some embodiments, one or more of the support portions may be curved. In some embodiments, the one or more support protrusions are integrally formed in the support structure. In some embodiments, the first branch portion and the second branch portion may be slidably supported on different support portions. In some embodiments, the force transmitting member may be configured to be supported on the support structure only by the branch portions. In some embodiments, the support structure has two support portions. Each support section can be associated with a single branch section. Each support portion may be configured to support a single branch portion.In some embodiments, the actuation mechanism includes an actuation member. The operating member may be configured to rotate when receiving a pressing force applied by a user. In some embodiments, the actuation member may be configured for thumb actuation by a user. In some embodiments, the actuating member is hingedly coupled to the support structure of the child seat, for example, by a pivot connector. In some embodiments, the actuating member includes a lever. In some embodiments, the lever may be hingedly coupled at a first end portion to the support structure of the child seat. In some embodiments, the lever may include an operating portion at a second end portion. In some embodiments, the actuation portion protrudes from the support structure through an opening. In some embodiments, the rotary connector defines a rotational axis. In some embodiments, the rotary connector may be configured such that the defined rotational axis extends substantially parallel to a linear direction of movement of the engagement portion. In some embodiments, the rotation axis may be configured to extend skew to a linear direction of movement of an engagement portion.In some embodiments, the operating member includes an operating surface for receiving an operating force from a user. In some embodiments, the actuation surface may extend perpendicular to an upper edge of the support structure. In some embodiments, the actuation surface may be configured to receive an actuation force in a direction tangential with respect to the top edge of the support structure.In some embodiments, the actuation member is movable between a locking position and a release position. The locking position may be a position in which an operation portion of the operation member extends in a substantially vertical direction on the child seat. The release position may be a position in which the operating member is rotated by a predetermined angle from the locking position. In some embodiments, the locking position may be a forward position of the operating member on the child seat and the release position may be a rearward position of the operating member of the child seat.In some embodiments, the operation member may include a force application portion. In some embodiments, the force applying portion is configured to contact an intermediate force transmitting member. In some embodiments, the force applying portion is provided between the first end portion and the second end portion of the operating member. In some embodiments, the force applying portion includes a protruding portion. In some embodiments, the protruding portion extends in a direction transverse to an imaginary line extending through the first end portion and the second end portion of the operating member. In some embodiments, the protruding portion extends in the rearward direction of the child seat. In some embodiments, the protruding portion is defined by a curved portion provided in the operating member. The curved portion may be formed to extend around a rotation center of a backrest portion of the child seat when the operating member is in the locking position. In some embodiments, the force applying portion has a rearward contact surface configured to be in sliding contact with or to come into sliding contact with the force transmitting member.In some embodiments, the actuation mechanism may include an intermediate force transfer member. The intermediate force transmitting member may be configured to receive a force from the operating member and distribute the received force to the force transmitting member and the rotatably movable locking member. In some embodiments, the intermediate force transmitting member may be configured as a lever. In some embodiments, the lever includes a first arm portion and a second arm portion. The first arm portion and the second arm portion may extend at an angle with respect to each other. The first arm portion and the second arm portion may extend from different sides of a rotating portion of the intermediate power transmission member. The rotating portion may be rotatably coupled to the support structure of the child seat by the rotating connector. In some embodiments, the intermediate force transmitting member may include a force receiving portion for receiving a force from the operating member. In some embodiments, the force receiving portion may form an upper portion of the intermediate force transmitting member. In some embodiments, the force receiving portion may extend upward from the rotary connector. In some embodiments, the force receiving portion may include a first contact surface. In some embodiments, the force receiving portion may include a second contact surface. In some embodiments, the first contact surface and the second contact surface may be provided on opposite sides of the intermediate force transmission member. In some embodiments, the first contact surface is configured for sliding contact with a force application portion of the actuation member. In some embodiments, the second contact surface is configured for sliding contact with a force receiving portion of the rotatably movable locking member. In some embodiments, the intermediate force transmitting member is rotatably coupled to the force transmitting member. For example, the intermediate power transmission member may be rotatably coupled to the power transmission member at the second arm portion. The force receiving portion may be provided at the first arm portion of the lever.In some embodiments, the actuation member, the intermediate force transfer member, and the rotatably movable locking member are rotatable about respective axes of rotation. In some embodiments, the axes of rotation may extend parallel to each other. In some embodiments, when the operating member is in the locking position, a connection point at which the second arm portion is connected to the force transmitting member is positioned within an imaginary triangle formed by connecting the rotation axes in a plane perpendicular to the rotation axes.In some embodiments, a trim cover is provided for a child seat. The child seat may be an infant seat. In some embodiments, the trim cover includes a flexible trim portion and a mounting portion. The flexible trim portion may be configured to cover at least an outer portion of a seat structure. The flexible trim portion may include a trim edge portion. In some embodiments, the attachment portion is configured to couple the trim rim portion to the seat structure. In some embodiments, the attachment portion is coupled to the trim edge portion and is configured to come into surface contact with the flexible trim portion at a position within the trim edge portion when the attachment portion is coupled to the child seat.In some embodiments, the attachment portion includes a base portion. In some embodiments, the base portion includes a reference portion support surface. In some embodiments, the trim portion support surface may extend between a front portion and a rear portion of the base portion. In some embodiments, the trim cover edge portion may be fixedly coupled to the front portion at a mounting region of the trim cover edge portion. For example, the trim cover edge portion may be fixedly coupled to the front portion such that the flexible trim cover portion extends along the trim cover portion support surface. In some embodiments, the cover portion support surface may form an outer surface of the base portion.In some embodiments, the attachment portion includes a support assembly. The support assembly may be configured to support the base portion on the seat structure in a predetermined orientation.In some embodiments, the support assembly is configured to support the base portion on the seat structure such that the trim portion support surface at least partially increases an outer surface area of the outer portion. In some embodiments, the outer surface portion faces laterally away from the seat structure.In some embodiments, the support assembly is configured to support the base portion on the seat structure such that the trim portion support surface extends at least partially beyond an edge portion that bounds the outer surface area of the outer portion.In some embodiments, the support assembly is configured to support the base portion on the seat structure such that the front portion including the attachment region of the trim edge portion is at least partially spaced from the edge portion that bounds the outer surface region of the outer portion.In some embodiments, the support assembly includes a support protrusion protruding from the base portion. In some embodiments, the support protrusion may protrude from an inner surface of the base portion. In some embodiments, the inner surface and the trim portion support surface may be disposed on opposite sides of the attachment portion. In some embodiments, the support protrusion may be formed as a continuous rib. In some embodiments, the support protrusion may include a support surface adapted to contact support protrusions on the seat structure. In some embodiments, the support surface and the support protrusions may be configured to come into surface contact with each other. In some embodiments, the support surface may include a planar contact surface configured to contact a support surface on the support protrusions.In some embodiments, the front portion has an outer surface and an opposing inner surface. In some embodiments, the trim edge portion may be disposed on the outer surface. In some embodiments, the trim edge portion may be wrapped around the front portion to enclose the front portion. The edge of the cover portion may be disposed on an inner side of the fixing portion.In some embodiments, the attachment portion is configured to retain the trim portion to the seat structure such that a substantially seamless transition from the trim portion to a rear cover of the child seat is provided. The rear cover of the child seat can be designed in the manner of a shell. The back cover may form a hard shell portion.In some embodiments, the front portion may be adapted to the shape of the rear cover, for example, to the shape of a rear cover edge portion of the rear cover, such that upon mounting the attachment portion to the seat structure, the front portion may be placed in a position within the rear cover in which the front portion overlaps with the rear cover such that the cover portion extends past the rear cover edge portion into the rear cover.In some embodiments, the front portion is provided on the base portion offset with respect to the reference portion support surface. In some embodiments, a transition portion, such as a step, may be provided between the front portion and the trim portion support surface. In some embodiments, the transition portion may define the trim portion support surface and be adapted to follow a contour of a backcover rim portion. In some embodiments, the attachment portion is configured such that the trim portion is supported on the trim portion support surface with an outer surface of the trim portion being disposed flush with an outer surface of the rear cover edge portion, and / or such that the trim portion is supported on the front portion with an outer surface of the trim portion being held between the front portion and the rear cover edge portion, for example, clamped between the front portion and the rear cover edge portion.In some embodiments, the attachment portion is configured to only partially close a gap formed on the child seat between the outer portion and the rear cover while holding the cover portion such that an opening defined between the rear cover, the outer portion, and an attachment portion, particularly an upper portion of the attachment portion mounted on the seat is covered by the cover portion. In some embodiments, the opening has a dimension that allows a user to pass a finger through the opening while deforming the trim portion covering the opening.In some embodiments, the attachment portion is configured to be coupled to the child seat with an insertion movement including a rotational push movement and / or may be configured to be decoupled from the child seat with a decoupling movement including a rotational pull movement.In some embodiments, the fastening portion is non-destructively detachably mountable to the child seat.In some embodiments, the attachment portion has a higher stiffness than the flexible trim portion.In some embodiments, the trim edge portion is sewn and / or adhered and / or clamped to the attachment portion.In some embodiments, a child seat may include a seat pan that provides a child accommodation space. In some embodiments, the child seat may include an inner crash cushion. The inner impact absorber may include a first impact protection portion configured to reduce impact on a seated child's shoulder in the event of a side impact. In some embodiments, the first impact protection portion includes regions having different cushioning properties. In some embodiments, the regions having different damping properties are provided by regions having different material stiffness in the inner impact damper. In some embodiments, the first impact protection portion includes an upper end portion and a lower end portion. In some embodiments, the lower end portion on the seat pan is disposed closer to the hip region of a seated child than the upper end portion. In some embodiments, the upper end portion is configured more rigid than the lower end portion.In some embodiments, the lower end portion is configured to catch the shoulder of a child having a first size, for example, a child having a minimum allowable size for the child seat. In some embodiments, the upper end portion is configured to catch the shoulder of a child having a second size greater than the first size, for example, a maximum allowable size for the child seat. In some embodiments, the different damping properties are provided by mechanical weakening sections in a material. Such mechanical weakening sections can be provided by recesses, grooves, holes, etc. In some embodiments, the first impact protection portion may be integrally formed. In some embodiments, the internal impact damper may include a foam material, for example a closed cell foam material. In some embodiments, the foam material comprises expanded polypropylene. In some embodiments, the foam material may have a density of substantially 30 g / l.In some embodiments, the child seat may include a seat structure defining an inner accommodation space for a child. In some embodiments, the child seat may include a side impact protection assembly configured to initiate a seating movement and / or a head movement of a seated child about the vertical axis in the event of a side impact. In some embodiments, the side impact protection assembly includes an outer rear side bumper. The outer rear side bumper may be supported on an outer side of the seat structure. The outer rear side bumper may be supported on the outside of the seat structure in a region rearward of the inner accommodation space. In some embodiments, the seat structure includes a seat pan that defines the accommodation space.In some embodiments, the seat structure includes a support portion that supports the seat pan. In some embodiments, the seat structure may include a beam-like support portion as described herein. In some embodiments, the support portion defines a support surface facing a central longitudinal plane of the seat structure. In some embodiments, the rear side bumper is housed in the support portion. In some embodiments, the rear side bumper is housed in a reinforcing structure of the support portion. In some embodiments, the rear side bumper is accommodated in the support portion so as to protrude laterally from the support portion.In some embodiments, the side impact protection assembly further includes an outer front side bumper supported on the seat structure at a level of a seated child's chest and / or an inner impact bumper. In some embodiments, the inner impact bumper may be provided on and extend along the seat shell of the child seat from a head portion of the seat down to the hip portion and / or at least to a lower end of the chest of a seated child. In some embodiments, the inner impact absorber may be integrally formed from a single material. In some embodiments, the inner impact damper may comprise a plastic material. In some embodiments, the internal impact damper may include a foam material, for example a closed cell foam material. In some embodiments, the inner impact damper may be made of expanded polypropylene. In some embodiments, the inner impact absorber may be made of a material having a density of substantially 30 g / L. In some embodiments, recesses and / or openings may be provided in a lower end portion of the crash cushion. In some embodiments, the recesses and / or openings may have different shapes and sizes and are provided to reduce the stiffness of the crash cushion in the lower end portion to a more suitable stiffness for smaller children.In some embodiments, the rear side bumper and the front side bumper are spaced apart from each other and / or are formed as separate parts. In some embodiments, the rear side bumper and the front side bumper protrude from the seat structure parallel to each other. In some embodiments, the rear side bumper may have a free end portion and a fixed end portion. In some embodiments, the front side bumper has a free end portion and a fixed end portion. In some embodiments, each free end portion may define a force receiving surface. In some embodiments, the force-absorbing surfaces of the rear side bumper and the front side bumper may be positioned at substantially the same level, for example, at the same lateral level and / or at the same vertical level. In some embodiments, the force receiving surfaces of the rear side bumper and the front side bumper may be positioned such that the force receiving surface of the rear side bumper is disposed laterally further outward than the force receiving surface of the front side bumper.In some embodiments, the side impact protection assembly is configured such that forces resulting from a side impact and acting on the child seat in the lateral direction are first absorbed by the rear side bumper and / or are transferred to the seat structure to a greater extent from the rear side bumper with less impact absorption compared to the front side bumper.In some embodiments, the rear side bumper is more rigid than the front side bumper. In some embodiments, the rear side bumper may have a density of 50 g / L. In some embodiments, the front side bumper may have a density of 27 g / L. In some embodiments, the rear side bumper may protrude further in the lateral direction than the front side bumper. In some embodiments, the front side bumper and / or the rear side bumper may include or be made of EPS material.In some embodiments, the child seat may include an exterior side impact protection assembly provided on an exterior of the seat pan and configured to, in the event of a side impact, cushion an impact on the seat pan in a region of a seated child's chest. In some embodiments, the exterior side impact protection assembly includes a front side bumper configured as an impact bumper and supported on the seat pan at the level of a chest of a seated child. In some embodiments, the front side bumper is configured such that a lower end portion thereof provides lower rigidity compared to an upper portion thereof.In some embodiments, the front side bumper is configured and arranged to reduce its dimension toward its lower end portion.In some embodiments, the front side bumper has a wider upper end portion and a narrower lower end portion. In some embodiments, the shape of the front side bumper may be triangular or drop shaped.In some embodiments, the outer side impact protection assembly may be combined with the inner impact damper. In some embodiments, the front side bumper and the inner crash cushion are arranged in series in the lateral direction such that forces resulting from a side impact are transmitted through both the front side bumper and the inner crash cushion. In some embodiments, the inner impact absorber includes a first impact protection portion configured to reduce impact on the shoulder of the seated child in the event of a side impact and includes areas having different damping characteristics. In some embodiments, the first impact protection portion may include an upper end portion and a lower end portion. The lower end portion may be disposed on the seat pan closer to the hip region of a seated child than the upper end portion. In some embodiments, the upper end portion is configured more rigid than the lower end portion. In some embodiments, the front side bumper comprises or consists of a material having a lower density than the inner crash cushion.In some embodiments, the head restraint assembly of the child seat may be configured to reduce acceleration of the head of the seated child in the event of a side impact. In some embodiments, the headrest assembly includes a head movement inducing structure.In some embodiments, the head movement inducing structure is configured such that when a seated child's head contacts the headrest assembly as a result of a side impact, rolling movement of the child's head is induced to at least partially reduce acceleration of the head. In some embodiments, the head movement inducing structure may be configured to induce a predetermined rolling movement sufficient to reduce the acceleration of the head while preventing an excessive increase in forces acting on the neck of the seated child.In some embodiments, the headrest assembly includes a headrest portion having a rear inner support surface and inner lateral support surfaces. For example, the headrest assembly may include a left inner support surface and a right inner support surface. In some embodiments, the inner lateral support surfaces are formed in a convex shape in a cross section along a vertical plane extending in the lateral direction of the headrest assembly. In some embodiments, the inner lateral support surfaces are configured to bulge toward the inner accommodation space. The head restraint can be adjustable in height. In some embodiments, each of the inner lateral support surfaces has a bottom surface portion and a top surface portion that are interconnected by a rounded apex portion. Each apex portion may be provided at a position of the inner side support surfaces that, when the headrest portion is correctly adjusted to the size of a seated child, is disposed between an upper end portion and a center of the head of the seated child.In some embodiments, the child seat includes a headrest impact protection assembly configured to catch the headrest assembly in the event of an impact. In some embodiments, the headrest impact protection assembly is configured to provide a cushioning effect on the headrest assembly in a side impact direction and / or in a rear impact direction.In some embodiments, the headrest impact protection assembly includes a headrest impact protection portion shaped corresponding to a rear portion of the headrest assembly.In some embodiments, the headrest impact protection portion has an inner surface facing the headrest assembly and the headrest assembly has an outer surface facing the inner surface. In some embodiments, the inner surface and the outer surface extend at least partially substantially parallel such that they can come into surface contact in the event of an impact.In some embodiments, the inner surface and the outer surface may be curved. In some embodiments, the outer surface may form a rear corner region of the headrest assembly and the inner surface may extend around the rear corner region from behind the headrest assembly to a lateral side of the headrest assembly.In some embodiments, the headrest impact protection assembly is integrally formed with the inner impact absorber. In some embodiments, the inner impact bumper defines the headrest impact protection portion as a second impact protection portion and includes the first impact protection portion providing cushioning for the shoulder portion and / or the chest of a seated child.In some embodiments, the inner impact bumper is attached to a seat shell of the child seat and the headrest impact protection portion protrudes further into the interior of the seat shell than the first impact protection portion to reduce the space between the headrest impact protection portion and the headrest assembly.In some embodiments, the headrest assembly has an outer contour with a U-shape. In some embodiments, the headrest arrangement may have an inner contour with a V-shape, for example when the headrest is viewed from vertically above, for example in plan view.In some embodiments, a child restraint system includes a stationary portion and the movable portion. The stationary portion may be a portion of a main body of a base, for example a base, as described in other portions of the present specification. The portion of the main body may be a front end portion of the main body. In some embodiments, the stationary portion may be a secondary support portion on the main body. The secondary support portion may be configured as described in connection with other embodiments in this specification. The movable portion may be a retaining portion of the child seat. In other configurations, the movable portion may be an upper end portion of a load leg. The movable portion may be movable toward and away from the stationary portion. The movable portion and the stationary portion may each have an edge portion, the edge portions approaching each other when the movable portion is moved toward the stationary portion. At least one edge portion of the edge portions of the movable portion and the stationary portion has an elastically deformable portion or is defined by an elastically deformable portion.In some embodiments, the stationary portion is a front portion of the main body of the base to which a load leg is rotatably coupled, and the movable portion is a coupling portion of the load leg.In some embodiments, the coupling portion and / or the main body are configured such that a transition between their outer surfaces is substantially seamless when the load leg is in a use position. The coupling portion and / or the main body may comprise an elastically deformable lip or strip attached to the rim portion. The elastically deformable lip or strip may be a rubber lip or strip.In some embodiments, the stationary portion is a secondary support portion on the main body as described in connection with other embodiments in this specification. The movable portion may be a retaining portion of the child seat engageable with the secondary support portion. The retaining portion of the child seat may be configured in a manner as described in connection with other embodiments in this specification having retaining portions. The secondary support portion may include the elastically deformable portion. The elastically deformable portion may be made of rubber. The elastically deformable portion may be provided at least at a portion of the secondary support portion facing toward an entering retaining portion. The elastically deformable portion may be configured to protrude from the support structure of the secondary support portion. For example, the elastically deformable portion may protrude laterally from the support structure of the secondary support portion. Generally, the elastically deformable portion protrudes further outward from the secondary support portion than any rigid portion that could contribute to pinching of a user's finger.In some embodiments, the elastically deformable portion protrudes laterally from the secondary support portion such that the retaining portion, when moving into the secondary support portion, first has to pass the elastically deformable member or first has to pass under the elastically deformable member. The elastically deformable portion may be a cover.In some embodiments, the elastically deformable portion includes a cover covering an upper surface of a free end portion of the secondary support portion such that any rigid member or edge of such member is positioned further inside the deformable portion or the cover in a moving direction of the retaining portion.In some embodiments, the elastically deformable portion has a hardness of 80 Shore A or less. The elastically deformable portion may comprise a thermoplastic elastomer material, for example TPE-S or SEBS.In some embodiments, the upper surface portion of the base includes at least one further protrusion adjacent to the primary support portion. The further protrusion may be a bead. The further protrusion may be a rib. Two or more further projections can be provided. The further protrusion may extend over a predetermined angular range about the rotational axis defined by the primary support portion. The further protrusion may be configured to prevent excessive surface contact between a lower surface of the child seat and the upper surface portion of the base. In some embodiments, the further protrusion extends along a curved path. The curved path may be circular. In some embodiments, the top surface portion of the base includes two or more of the further protrusions extending along at least two different concentric circles about the axis of rotation. In some embodiments, the protrusions are offset from each other. In some embodiments, the protrusions extend between different angular positions about the rotational axis. In some embodiments, the protrusions extending along different concentric circles at least partially overlap each other in the radial direction, for example, in a radial direction away from the rotational axis defined by the primary support portion.In some embodiments, a lower surface portion of the child seat includes at least one protrusion. The lower surface portion may be a surface portion of the child seat that extends around an interface portion, such as the interface portion, as described in other embodiments of this specification. The at least one protrusion is configured to prevent excessive surface contact between an upper surface portion of the base and a lower surface portion of the child seat. The protrusion may be a bead. The protrusion may be a rib. The protrusion may extend over a predetermined angular range about the interface portion and / or about a rotational axis defined by the interface portion. The protrusion may extend along a curved path, wherein the curved path may be circular. The lower surface portion of the child seat may have two or more protrusions extending along at least two different concentric circles around the interface portion and / or around the rotational axis. In some embodiments, the protrusions are offset from each other and / or extend between different angular positions about the interface portion and / or about the rotational axis. In some embodiments, protrusions extending along different concentric circles at least partially overlap each other in the radial direction, for example, in a radial direction away from the rotational axis defined by the interface portion.In some embodiments, the child seat includes a belt receiving portion configured to receive a seatbelt portion of a vehicle seat for mounting the child seat to the vehicle seat. The child seat further includes a blocking portion configured to be moved between a blocking position in which insertion of the belt portion into the belt receiving portion is blocked and a releasing position in which insertion of the belt portion into the belt receiving portion is permitted. The receiving portion may have a recess and the blocking portion may have a free end portion configured to be received in the recess when the blocking portion is in the blocking position.In some embodiments, the blocking portion is configured to protrude at least partially from below into the belt receiving portion when positioned in the blocking position.In some embodiments, the blocking portion is linearly movable. The blocking portion may be supported on a support. The blocking portion may be supported on the carrier by means of a spring, for example a spring acting in the direction of movement of the blocking member and / or urging the blocking member in a direction away from the carrier. The carrier can be guided linearly in a supporting structure of the child seat. The blocking portion may be linearly guided on the carrier, for example in a guide recess. A spring may be disposed between a rear end of the blocking portion and a bottom portion of the guide recess.In some embodiments, the child seat further includes a seat structure having a seat bottom and a seat back. The seat structure may be configured to be transitionable between a seat configuration and a reclining configuration. The blocking portion may be operatively connected to the seat structure such that the blocking portion is moved to the blocking position when the seat structure is transferred to the reclining configuration and is moved to the release position when the seat structure is transferred to the seat configuration.In some embodiments, the seat back includes a force application portion and the blocking portion includes or is force-transmittingly coupled to a force receiving portion operatively connected to the force application portion. The force receiving portion may be slidably held on the force applying portion.The blocking portion may be guided along a predetermined path. For example, the blocking portion may be guided along a straight path or a curved path. The predetermined path may extend in an upward direction and / or may be provided in a support structure of the child seat. The predetermined path may be defined by a slot provided in the support structure. The support structure may include the belt receiving portion and / or may rotatably support at least the seat back. The force applying portion may include a slit, and the force receiving portion may be slidably received in the slit.In some embodiments, the child seat includes a belt receiving portion configured to receive a seatbelt portion of the vehicle seat for mounting the child seat to a vehicle seat, the belt receiving portion being disposed at a rear side of the seat back. The belt receiving portion is configured to be transferable between an active configuration in which insertion of the seatbelt portion is possible and an inactive configuration in which insertion of the seatbelt portion into the belt receiving portion is not possible.In some embodiments, the belt receiving portion is transitioned to the inactive configuration when the seat structure is transitioned to the reclining configuration and is transitioned to the active configuration when the seat structure is transitioned to the seat configuration. In some configurations, the strap receiving portion is configured and arranged such that a transition of the seat structure to the reclining configuration is not possible or blocked when a seatbelt portion is received in the strap receiving portion.In some embodiments, the belt receiving portion is provided on the seat back so as to be integrally movable therewith. The seat back may be rotatably coupled to the support structure to transition the seat structure between the seat configuration and the reclining configuration. The seat back and the support structure may be configured such that, when the seat structure is in the reclining configuration, at least an insertion region of the belt receiving portion is covered by the support structure.In some embodiments, the seat back and support structure are configured such that when the seat structure is in the reclining configuration, the strap receiving portion is completely covered by the support structure and is thus inaccessible to a user for inserting a seatbelt portion.In some embodiments, the trim cover is provided for a child seat. The trim cover includes a trim flexible portion configured to cover at least an outer portion of the seat structure, the trim flexible portion including a trim edge portion. The trim cover further includes a mounting portion for coupling the trim cover edge portion to the seat structure. The attachment portion is coupled to the trim edge portion at a coupling region. The attachment portion extends along the flexible trim portion with an outer side thereof facing an inner side or inner surface of the flexible trim portion. The inner side or inner surface of the attachment portion has a support protrusion configured to be supported at an edge portion of the outer portion.In some embodiments, the coupling region is fastened to the cover edge portion along a fastening line, wherein the fastening line can extend substantially parallel to the cover edge portion.In some embodiments, the coupling region is sewn to the cover edge portion along a line of stitching, the line of stitching forming the line of attachment.In some embodiments, the support protrusion extends on the inner side of the attachment portion following the attachment line, for example, parallel to the attachment line and / or parallel to an imaginary straight line extending through end points of the attachment line.In some embodiments, the support protrusion defines or comprises a support surface, wherein the support surface is provided on a lateral side of the support protrusion that is facing away from the coupling region.In some embodiments, the attachment portion is coupled to the flexible trim portion on only one side. In some embodiments, the support protrusion is straight.In some embodiments, the attachment portion is a substantially flat rigid member. In some embodiments, the attachment portion may be substantially rectangular. The coupling region may be provided at a longitudinal end portion of the fastening portion. The fastening line may extend in the transverse direction of the fastening portion. The support protrusion may be provided at a position between longitudinal ends of the fixing portion.In some embodiments, the attachment portion may be configured to hook to an edge portion of a seat structure and support the trim edge portion at a predetermined distance from the edge portion of the seat structure.In one embodiment, the child seat includes a seat pan that provides an inner accommodation space for a child. The child seat further comprises an outer side impact protection arrangement provided on an outer side of the seat shell and configured to, in the event of a side impact, dampen an impact on the seat shell in a region of a rib cage and / or in a region of the head of a seated child. The outer side impact protection assembly includes an impact damper supported on the seat pan. The impact damper extends laterally outwards from the seat shell in the transverse direction of the child seat. The impact damper tapers towards its laterally outermost portion and / or tapers towards a front end portion.In some embodiments, the impact absorber tapers at least partially radially towards its laterally outermost portion. In some embodiments, the impact absorber tapers at least partially stepwise towards its laterally outermost portion.In some embodiments, the exterior of the crash cushion is provided as a relief to provide different cushioning properties in different areas of the exterior.In some embodiments, the damping characteristics are distributed such that a side impact on the impact damper, applied by, for example, an imaginary planar force application surface extending perpendicular to a transverse direction of the child seat, is optionally first slightly damped in an intermediate portion by compressing the intermediate portion in the transverse direction of the child seat to a level at which the force application surface contacts a stiffer rear portion of the impact damper, and then transmitted to the rear portion, thereby inducing rotation in the seat structure. Optionally, the intermediate portion may then be further compressed with gradually increasing stiffness due to the tapered shape of the crash damper.In some embodiments, an elongated central portion that is elevated above an adjacent upper portion and / or an adjacent lower portion of the crash cushion extends at least partially from a front end portion toward a rear end portion of the crash cushion.In some embodiments, the impact absorber has an outwardly curved shape with an enlarged outer surface portion extending from the rear end portion to the front end portion. The arcuate outer surface portion may be provided at the elongated central portion.In some embodiments, the outermost lateral portion is provided in an intermediate portion of the shock absorber between the front portion and the rear portion.In some embodiments, the impact absorber is integrally formed from a single material. In some embodiments, the material is a closed cell material. In some embodiments, the closed cell material is expanded polystyrene (EPS).In some embodiments, a rear end portion of the crash cushion has a higher stiffness as compared to the front end portion.In one embodiment, a head restraint assembly for a child seat is provided. The headrest assembly includes a headrest base body having a rear wall and two side walls defining an inner accommodation space for a seated child's head. The headrest assembly further includes a first cushioning portion provided at a rear inner region of the side wall. Further, the headrest assembly includes a second cushioning portion provided at a front portion of the side wall. The second cushion portion continues from a front end portion of the first cushion portion.In some embodiments, the second damping portion includes a coupling portion at least partially inserted into a receiving space provided between the base body and the first damping portion. For example, the receiving space can be provided between a recess of the base body and the first damping section. A plurality of receiving spaces may be provided. The coupling portion may include a protrusion inserted into the recess. In a modification, the coupling portion may include two or more protrusions inserted into two or more recesses.In some embodiments, a transition from the first damping portion to the second damping portion is at least partially stepped. A rear end portion of the second damping portion may protrude beyond an inner contour of the adjacent first damping portion at the front end portion of the first damping portion. A sharp edge may be provided by the second damping material. The sharp edge may extend in or along a plane.A rear side surface portion of the second cushioning portion and a front side surface portion of the first cushioning portion may face each other. Additionally or alternatively, the front side surface portion and the rear side surface portion may extend parallel to each other. The front side surface portion and the rear side surface portion may extend along a reference plane extending in a transverse direction of the headrest assembly. The reference plane may extend perpendicular to a vertical central plane of the headrest base body.In some embodiments, the headrest base body is U-shaped when viewed from above, and includes a base and two legs. The base may be formed by a rear end portion of the headrest base body, and the legs may be formed by two side portions of the headrest base body. The rear portion may include the rear wall and each side portion may include a side wall. The headrest base body may have a main extension direction transverse to the extension directions of the legs from the base. The reference plane may extend at an angle with respect to the main extension direction, for example such that an upper portion is arranged further in the forward direction than a lower portion.In some embodiments, a rear cavity is provided between a rear lower portion of the first cushion portion and a portion of the headrest base body.In some embodiments, the first cushioning portion is made of an expanded foam material, such as EPP. Additionally or alternatively, the second damping section can be made of a polyurethane material, for example PU foam.In another embodiment, a headrest assembly includes a headrest base body and an impact absorbing portion provided at an inner side of the headrest base body. The headrest base body has a rear wall and two side walls defining an inner accommodation space for the head of a seated child. The impact absorbing portion is integrally formed of a single material. For example, the impact absorbing portion may be formed of or include an expanded foam material such as EPP. A side portion of the impact absorbing portion extending along the side wall has a trough-like recess on the outside thereof.The trough-like recess may provide an inner wall portion with reduced material thickness in the impact absorbing portion. A cavity may be created between the inner wall portion and the side wall to provide a region of reduced stiffness and / or hardness of the side portion and / or increased flexibility.In some embodiments, a rear portion of the trough-like recess is at least partially defined by an inclined planar surface. The entire rear portion may be formed as a planar surface. In a modification, the rear portion may be at least partially defined by a curved surface and / or at least partially formed by a planar surface. Each surface may extend such that a material thickness increases in a rearward direction of the impact absorbing portion toward the rear portion of the side portion. If an oblique planar surface is provided, the surface may extend at an angle with respect to a vertical central plane of the impact absorbing portion, for example at an angle of 45 degrees or less.In some embodiments, an edge portion extending at least partially around an opening of the tub-like recess contacts the headrest base body.In some embodiments, the headrest base body and the impact absorbing portion have a U-shape. Each side portion may define a leg of the U-shape.In some embodiments, the trough-like recess extends over more than half the length of the side portion between the front end of the side portion and a rear end of the side portion. Additionally or alternatively, the trough-like recess may extend over more than half the width of a side portion between a lower end and an upper end of the side portion.In some embodiments, additionally or alternatively, the trough-like recess tapers inwardly in the transverse direction of the headrest assembly, the trough-like recess tapering toward a front end of the side portion. In some configurations, the trough-like recess may have a volume of 50 ml or more, for example 100 ml or more or 200 ml or more.In another embodiment, a child seat is provided with a seat structure and a headrest assembly. The seat structure includes a backrest portion having a rigid backrest base body and an inner padding. The backrest base body may be a seat pan. The headrest assembly includes a flexible side portion configured to flex outward during a side impact. The inner pad includes a headrest portion and an adjacent portion adjacent to the headrest portion. The headrest portion is provided at a side portion of the backrest base body in the region of the headrest arrangement. The adjacent portion may be a shoulder support portion or an upper arm support portion. The adjacent portion extends at least below the headrest portion at the side portion of the backrest body along a narrow side of the headrest portion. In some configurations, the hardness of the headrest portion is less than the hardness of the adjacent portion. In some embodiments, the stiffness of the headrest portion is less than the stiffness of the adjacent portion. In some embodiments, the density of the headrest portion is less than the density of the adjacent portion.In some embodiments, a transition from an inner surface of the adjacent portion to an inner surface of the headrest portion is smooth. Additionally or alternatively, the transition may be substantially seamless.In some embodiments, the headrest portion partially forms an end edge of the upholstery.In some embodiments, the adjacent portion and the headrest portion include a foam material. The adjacent section may comprise a closed cell foam material, for example EPP. The closed cell foam material may have a density of substantially 30 g / l. Additionally or alternatively, the headrest portion may comprise an open-cell foam material.Other features of the present invention will become apparent from consideration of the above-contained information, as well as in or in combination with the following detailed description, drawings and claims, and configurations given in the structured structure of aspects below. The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGSThe accompanying drawings, which are incorporated herein and form a part of the specification, illustrate possible configurations of embodiments and, together with the description, further serve to explain the principles of the embodiments and to enable one skilled in the art to make and use the embodiments. It is noted that the same or similar parts are denoted by the same reference numerals in the different figures. FIG. 1 is a perspective view of a base according to an example configuration. FIG. 2 is a side view of the base shown in FIG. 1. FIG. 3 is a sectional view of a primary support portion of the base according to an exemplary configuration. FIG. 4 is a perspective view showing an exemplary configuration of an engaging portion engageable with the primary support portion shown in FIG. 3. FIG. 5 is a bottom view showing an exemplary configuration of an interface of the child seat. FIG. 6 shows a schematic top view of components of a locking mechanism that may be used in the example configuration shown in FIG. 5. FIG. 7 is a bottom perspective view of an exemplary configuration of a child restraint system. FIG. 8 is an enlarged perspective view showing an exemplary configuration of a secondary support portion. FIG. 9 shows internal details of the secondary support portion illustrated in FIG. 8. FIG. 10 shows a perspective view of a support structure according to an example configuration. FIG. 11 is a perspective view showing an exemplary configuration of a secondary support portion including a locking mechanism. FIG. 12 is a perspective view of internal components of the locking mechanism. FIG. 13 is a perspective view of a base for a child seat according to an exemplary configuration. FIG. 14 is a side view of the base shown in FIG. 13. FIG. 15 is a perspective view of a base for a child seat according to an exemplary configuration. FIG. 16 is a side view of the base shown in FIG. 15. FIG. 17 shows a perspective view of a possible internal configuration of the base for a child seat. FIG. 18 shows a perspective view of a possible internal configuration of the base for a child seat. FIG. 19 is a sectional view of a clamping mechanism according to an exemplary configuration. FIG. 20 is a perspective view of components of the clamping mechanism. FIG. 21 is a perspective view of components of a release mechanism according to an example configuration. FIG. 22 is an enlarged perspective sectional view of components of the clamping mechanism according to an exemplary configuration. FIG. 23 is an enlarged sectional view showing an exemplary configuration of a display device with an operation member positioned in a storage position. FIG. 24 is the enlarged sectional view of FIG. 23 with the operating member positioned at a display position. FIG. 25 shows the enlarged sectional view of FIG. 23, with the actuator positioned in an extended position. FIG. 26 shows side views of possible configurations of a base. FIG. 27 is a perspective view of an exemplary configuration of the base showing actuation of a release mechanism. FIG. 28 shows a top view of a base according to an example configuration including a sensor assembly with at least one seat detection sensor. FIG. 29 is a bottom view of the base according to an example configuration including a sensor assembly having sensors in a first connector and a second connector for securing the base to a mounting structure. FIG. 30 is a perspective view of a locking member of an example locking mechanism. FIG. 31 illustrates components of a sensor assembly for sensing movement of the locking member shown in FIG. 30. FIG. 32 shows a possible configuration of a primary support portion in which a seat detection sensor is provided. FIG. 33 shows a configuration in which a magnetic sensor for detecting the presence of a load leg is provided at a lower portion of the base.FIGS. 34 to 36 illustrate various states of a load leg during a mounting process of a base according to an exemplary configuration.Figs. 37 and 38 show sectional views through a coupling portion of the load leg and how it is rotatably mounted on a main body of a base. FIG. 39 is a perspective view of a load leg according to an exemplary configuration. FIG. 40 is an enlarged perspective view of a coupling portion of the load leg illustrated in FIG. 39. FIG. 41 is a sectional view showing a magnet in the load leg and its position with respect to a load leg detection sensor when the load leg is in an extended position. FIG. 42 is a sectional view showing a magnet in the load leg and its position with respect to a load leg detection sensor when the load leg is in the storage position. FIG. 43 is a plan view of a display portion according to an exemplary configuration. Fig. 44 shows an alternative configuration of a display portion. Fig. 45 shows another alternative configuration of a display portion. FIGS. 46 and 47 show a possible configuration of a coupling arrangement in a perspective view. FIG. 48 shows an exploded view of a connector of an example coupling assembly. FIG. 49 is a perspective view of internal components of the connector shown in FIG. 48. FIG. 50 shows a top view of components of a locking mechanism and shows a locking component in the locking position. FIG. 51 shows a top view of the components of FIG. 50 with a locking member in the release position. FIG. 52 is a schematic illustration of a landing zone in which a child seat may be coupled to the base. FIG. 53 is a perspective view of a child seat according to a possible configuration. FIG. 54 is an enlarged fragmentary view of the child seat of FIG. 53. FIG. 55 is a side view of a child seat according to a possible configuration. Fig. 56 shows an enlarged portion of the side view of Fig. 55. Fig. 57 shows a partial side view of the child seat of Fig. 55 with a partially assembled reference. FIG. 58 shows an arrangement of the trim cover on the child seat at the beginning of an assembly process. FIG. 59 illustrates a child seat with a fully assembled trim. FIG. 60 shows a perspective view of an outer side of a fastening portion according to a possible configuration. FIG. 61 shows a perspective view of an inner side of a fastening portion according to a possible configuration. FIG. 62 is an enlarged partial view of a child seat, specifically showing a portion where the fastener can be supported. FIG. 63 is an enlarged sectional view of a child seat showing a mounted fastener from inside the child seat. FIG. 64 is a rear perspective view of a child seat configured as an infant seat. FIG. 65 is a front perspective view of the child seat shown in FIG. 64. FIG. 66 shows a perspective view of a mounting bracket used to couple a rear cover of the child seat of FIGS. 64 and 65 to a support structure of the child seat. FIG. 67 is a front perspective view of a head restraint assembly of the child seat shown in FIG. 64. FIG. 68 is a plan view of the headrest assembly shown in FIG. 67. FIG. 69 is a rear perspective view of the headrest assembly shown in FIG. 67. FIG. 70 shows a perspective front view of a child seat which is designed as a baby seat. FIGS. 71 and 72 show a sectional view of the child seat of FIG. 70 along a central longitudinal plane of the child seat, wherein FIG. 71 shows a seat configuration and FIG. 72 shows a reclining configuration. FIG. 73 is a side view of the child seat of FIG. 70 with a side cover removed. FIG. 74 shows details of an operating mechanism for operating interface portions of the child seat shown in FIG. 70. FIG. 75 shows details of the power transmission member of the operating mechanism shown in FIG. 74. Figures 76 and 77 show further details of the operation of the actuating mechanism of Figure 74. Fig. 78 is an enlarged view of a secondary handle portion of a carrying handle used for carrying the child seat of Fig. 70. FIG. 79 is a partial view of the child seat of FIG. 70 showing details of a strap attachment assembly. FIG. 80 shows an example configuration of a strap attachment assembly. FIG. 81 shows another exemplary configuration of a strap attachment assembly. FIG. 82 shows a perspective view of a base according to an embodiment. FIG. 83 is an enlarged perspective view of a secondary support portion according to an embodiment. FIG. 84 is an enlarged perspective view of a front end portion of the base of FIG. 82. FIG. 85 is a perspective view of a rear side of the child seat according to an embodiment. FIG. 86 is a sectional view of a rear portion of the child seat shown in FIG. 85. FIG. 87 is an enlarged perspective and sectional view of a belt receiving portion of the child seat according to an embodiment. FIG. 88 is a side perspective view of a fixing portion of a cover according to an embodiment. FIG. 89 is a plan view of the fixing portion of FIG. 88. FIG. 90 shows a rear view of a child seat with an outer side impact protection assembly according to an embodiment. FIG. 91 shows a top view of the child seat of FIG. 90. FIG. 92 is a perspective view of an impact damper of the child seat of FIGS. 90 and 91. FIG. 93 shows attachment of the crash cushion of FIG. 92 according to an embodiment. FIG. 94 is an exploded view of portions of the headrest assembly according to an embodiment. FIG. 95 is a top view of the head restraint assembly of FIG. 94. FIG. 96 is a sectional view of the head restraint assembly of FIG. 95. FIG. 97 is an enlarged perspective view of an upper side portion of the seat back of the child seat according to an embodiment. FIG. 98 is a perspective view of a head restraint assembly according to another embodiment. FIG. 99 shows a side view of the head restraint assembly of FIG. 98. FIG. 100 shows a sectional view along a vertical central plane of the headrest assembly of FIGS. 98 and 99. FIG. 101 is a cross-sectional view taken along the horizontal center plane of the headrest assembly of FIG. 100. FIG. 102 shows a top view of the head restraint assembly of FIG. 101. FIG. 103 shows a front view of the head restraint assembly of FIG. 102. FIG. 104 is a side cross-sectional left-hand side view of the head restraint assembly of FIG. 103. FIG. 105 is an enlarged view of a transition portion of the headrest assembly. FIG. 106 is a perspective view of components of a release mechanism according to a modification.All figures are only schematic representations of exemplary embodiments in which, in particular, distances and dimensional relationships are not shown to scale.The features and advantages of embodiments will become more apparent from the detailed description given below, taken in conjunction with the drawings, in which like reference numerals designate corresponding elements throughout. In the drawings, like reference numerals generally indicate identical, functionally similar, and / or structurally similar elements.DETAILED DESCRIPTIONThe following detailed description is merely exemplary in nature and is not intended to limit the application and uses. Moreover, there is no intention to be bound by any theory set forth in the foregoing background or summary or the following detailed description.Embodiments of the present disclosure will be described in detail with reference to embodiments thereof as illustrated in the accompanying drawings. References to "a single embodiment," "an embodiment," "some embodiments," etc., indicate that the described embodiment(s) may include a particular feature, structure, or feature, but not necessarily each embodiment must include the particular feature, structure, or feature. Moreover, such formulations do not necessarily relate to the same embodiment. Further, when a particular feature, structure, or feature is described in connection with an embodiment, it is believed that it is within the knowledge of one skilled in the art to affect such feature, structure, or feature in connection with other embodiments, whether or not explicitly described.Spatially relative terms such as "below," "below," "lower," "above," "on," "upper," "opposite," and the like, may be used herein to facilitate the description to describe the relationship of one element or feature to (another) element(s) or feature(s), as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (e.g., rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein may also be interpreted accordingly.Terms describing parts or components as "detachable" and / or "detachable" refer to configurations in which the parts or components can be at least decoupled from another part or component without destroying one of the cooperating parts or components. These terms can also describe configurations in which the parts and components can be decoupled or detached without tools (without tools).Example Basic ConfigurationExample configurations of a base 2 can be seen from FIGS. 1 and 2. The base 2 is configured to be coupled to a vehicle seat 90 and configured to support a child seat 3 (for example, as in FIGS. 53 and 70 ). Thus, the base 2 may include various arrangements and features related to coupling the base 2 to the vehicle seat and / or features and configurations related to coupling a child seat (not shown in FIGS. 1 and 2 ) to the base 2.The base 2 may include a main body 20 configured to be positioned on the vehicle seat 90. At a front portion 4 of the base 2, a load leg 900 may be rotatably coupled to the main body 20.An anti-rebound portion 300 may be provided at a rear portion 5 of the base 2. The anti-rebound portion 300 may be configured to come into surface contact with a seat back 92 of a vehicle seat 90.The base 2 may further include a coupling interface 100. The coupling interface 100 may be a first type of coupling interface as mentioned in connection with other features and embodiments described in other parts of this specification. The coupling interface 100 is configured for releasable locking with a child seat to be supported on the base 2. Various types of child seats may be supported on the base 2, including an infant seat or a baby seat. Child seats 3 are described in other parts of this specification.Further, the base 2 may include a coupling assembly 200 for coupling the base 2 to a mounting structure 96 in the vehicle seat 90. For this purpose, the coupling arrangement 200 can have a coupling section 202 which can be releasably engaged with the fastening structure 96.The base 2 may include a tensioning mechanism 400 configured to generate a biasing force for urging the base 2 toward the vehicle seat 90 once the base 2 is operatively connected to the mounting structure 96 of the vehicle seat 90, for example, via the coupling portion 202.The base 2 may further include a support structure 600 (shown in FIG. 10 ) configured to securely support a child seat 3 on the base 2 in the event of an impact.The base 2 may further include a release mechanism 700 configured to release or unlock the coupling portion 202 from the mounting structure 96, and / or may be configured to release or disengage the tensioning mechanism 400, and / or may be configured to release or unlock movement of the coupling portion 202 relative to the anti-rebound portion 300.As is further illustrated in FIG. 1, the base 2 can have a sensor arrangement 800 which has one or more sensors for detecting specific states or conditions of the base 2 and / or of a child seat 3 supported on the base 2.The base may further include a display portion 1000 configured to provide centralized information about the status of the child restraint system.The base 2 may include a locking mechanism 500 for inhibiting rotation of a child seat 3 about a rotation axis.Although in FIGS. 1 and 2 and also in several of the figures described below, a configuration of the base 2 is shown in which all of the latter specific mechanisms and arrangements are provided, it should be appreciated that it is possible to implement the latter features, arrangements and mechanisms individually or to combine two or more thereof in a suitable manner.The coupling interface 100, the coupling assembly 200, the anti-rebound portion 300, the tensioning mechanism 400, the locking mechanism 500, the support structure 600, the release mechanism 700, the sensor assembly 800, the load leg 900, and the display portion 1000 may be considered individual functional blocks that may be implemented individually or in combination with one or more of the other functional blocks.Example Coupling InterfaceA possible configuration of a coupling interface 100 of the base 2 will be described below. As already illustrated in FIGS. 1 and 2, the coupling interface 100 can have a primary support section 101. The primary support portion 101 may protrude from an upper surface portion 118 of the base 2 in a first direction D 1. In the present configuration, the first direction corresponds to an upward direction in a mounted state of the base 2 on the vehicle seat 90.The primary support portion 101 is configured to be detachably engaged by an engagement portion of an inserted child seat 3 in a positive manner to block movement of the child seat 3 in the first direction D 1. The configuration of such a child seat 3 will be described later. The primary support portion 101 is further configured to support the child seat 3 rotatably about a rotation axis R 1 extending parallel to the first direction D 1. In the present configuration, the primary support portion 101 may include a circumferential recess 105 configured to engage with the child seat 3, specifically, to engage with a locking mechanism 50 as described later.FIG. 3 is an enlarged sectional view of the primary support portion 101. The primary support portion 101 may be formed as a protrusion. The primary support portion 101 may have a lateral outer surface 104. The lateral outer surface 104 may extend entirely around the primary support portion 101, more specifically around the rotational axis R 1 defined by the primary support portion 101. Due to the shape of the lateral outer surface 104, the primary support portion 101 may be configured to allow 360° rotation of an inserted child seat. In other words, when the coupling interface 100 includes only the primary support portion 101 as described, an inserted child seat may be rotated 360° about the rotation axis R 1 and inserted on the primary support portion in an arbitrary orientation. Further, such an arrangement enables a child seat 3 to be inserted in any angular orientation and to lock the same to the primary support portion 101.The primary support portion 101 may include a circumferential recess 105 provided in the lateral outer surface 104. The circumferential recess 105 is configured to receive an engagement portion 51, 52 of a child seat 3 to form a positive lock between the child seat and the primary support portion 101. In FIG. 3, a first engaging portion 51 is shown in a released state in which it is laterally spaced apart from the primary supporting portion 101. Further, a second engaging portion 52 is shown in an engaging state in which a portion of the engaging portion is inserted into the circumferential recess 105. In this way, movement of the engagement portion 52 and thus of the child seat 3 in the first direction D 1 is blocked by contact of the engagement portion with the primary support portion 101.Example Shape of Primary Support Portion - Cone ShapeAs also shown in FIG. 3, the primary support portion 101 according to the exemplary configuration may have a generally cone-like appearance. In particular, as shown in FIG. 3, the primary support portion 101 has the shape of a truncated cone with a free upper end having a narrower dimension. Since the engaging portions 51 are configured to be engaged from laterally outside the primary support portion 101, it is possible to couple the child seat to the primary support portion 101 at arbitrary angular orientations about the rotational axis R 1. In other words, the primary support portion 101 does not require to accurately position the child seat at a predetermined angular orientation to enable the child seat to be coupled to the primary support portion 101. Such a configuration provides an increased angular seating zone in which a child seat can be inserted on the primary locking portion 101.The primary support portion 100 may be configured to support the main weight of an assembled child seat. Accordingly, in an exemplary configuration, the main weight of an assembled child seat may be supported by an upper portion 107 of the primary support portion 101. In some embodiments, the weight of the child seat may be fully supported by the primary support portion 101. In some embodiments, the primary support portion 100 may be configured to support the child seat at a predetermined distance from the upper surface portion 118 of the main body 20 of the base 2. The primary support portion 101 may be configured as a stationary support portion. Accordingly, when a child seat is inserted on and coupled to the primary support portion 101, the child seat can be rotated about the primary support portion 101. It is also possible to provide an arrangement in which the primary support portion 101 is rotatably configured together with an inserted child seat.The primary support portion 101 may include an upper portion 107 supported by a pillar portion 106 in an overhanging manner. In this manner, an overhang portion 108 is provided. As shown in FIG. 3, the overhang portion 108 is available for establishing the positive locking between the child seat and the primary support portion 101. For example, the aforementioned circumferential recess 105 may be bounded by a bottom surface 109 of the top portion 107 and an outer surface 114 of the pillar portion 106. However, in some configurations, there need be no recess, and coupling between the child seat 3 and the primary support portion 101 can be established by simply enclosing or receiving the overhang portion 108 in the seat. The pillar portion 106 may be at least partially tapered towards the upper portion 107. The primary support portion 101 may have a mushroom-like shape.The upper portion 107 may have a layered structure. The upper portion 107 may include an upper layer 110 and a lower layer 111. The lower layer 111 may be configured to support the upper layer 110. The upper layer 110 may be configured to come into sliding contact with a lower support surface 34 of the child seat to be supported. FIGS. 4 to 6 show details of a child seat 3 which can be supported on the primary support section 101. The aforementioned support surface 34 is visible in Fig. 5 and possible features of the child seat 3 will be described in more detail later.The lower layer 111 may have a higher rigidity than the upper layer 110. The upper layer 110 may include a low friction material. The low friction material may be a synthetic material. For example, the low friction material used in accordance with some embodiments may include polyoxymethylene (POM). The low friction material is configured to come into sliding contact with the child seat 3, more specifically with the above-described lower support surface 34 of the child seat 3. The lower layer 111 may include a metal material. The upper layer 110 may at least partially surround an outer periphery of the lower layer 111. In this way, contact between the lower support surface 34 of the child seat 3 and the lower layer 111 is prevented. As also shown in FIG. 3, the bottom surface of the lower layer 111 may be exposed or uncovered so that the engaging member 51 of a mounted child seat 3 may directly contact the lower layer 111.As shown in FIGS. 1 and 3, the top layer 110 may have a sliding surface 112 extending around a recess 113. The upper layer 110 may have the shape of a circular plate with a central circumferential recess 113. The sliding surface 112 may have a ring shape as shown in FIG. 1. An annular sliding surface 112 provides controlled friction between an inserted child seat and the primary support portion 101 when the child seat 3 is rotated.In some embodiments, the recess 113 is mechanically encoded so that another part, for example an insert such as a sticker, can be inserted into the recess only in proper alignment. FIG. 82 shows an exemplary configuration. The recess 113 may be substantially circular. The recess 113 may include a protrusion 113 aextending laterally inward into the recess 113. The mechanically coded recess can act as a positioning aid and the protrusion can act as a positioning portion. The protrusion may protrude into the recess in the radial direction. A plurality of protrusions may be provided.As illustrated in FIG. 3, the primary support portion 101 may be configured as a hollow body. The hollow body may be closed at the top and define an accommodation space 115 in the interior thereof. The storage space 115 may be configured to receive a portion of a tensioning mechanism 400 and / or a sensor of a sensor assembly 800 (see, for example, sensor 802 in FIG. 32 ). Generally, the accommodation space 115 is available for accommodating other portions of the base 2, thereby reducing the overall size of the base 2.Example Interface for Child SeatA child seat 3 that may be coupled to the above-described one of the base 2, specifically, the primary support portion 101 will be described below. FIGS. 4 to 7 illustrate possible configurations of the child seat 3.FIG. 5 is a bottom view of a child seat 3 according to an embodiment. The child seat 3 may include an interface portion 30 that is detachably engageable with the primary support portion 101. The interface portion 30 may include a recess 31 configured to receive the primary support portion 101 when the child seat 3 is inserted on the base 2. When the child seat 3 is inserted on the base 2, an insertion direction of the child seat 3 is opposite to the above-described first direction D 1 in which the primary support portion 101 protrudes from the base 2. Accordingly, in a mounted state of the child seat 3 on the base 2, the recess 31 extends in the first direction D 1 to be able to accommodate the primary support portion 101.The interface portion 30 may include a support surface 34 configured to contact a longitudinal end portion of the primary support portion 101. The longitudinal end portion of the primary support portion 101 may be a free end portion of the primary support portion 101. For example, the longitudinal end portion of the primary support portion 101 may correspond to the above-described upper portion 107 of the primary support portion 101. The support surface 34 may be a planar surface. The support surface 34 may be configured to come into sliding contact with the upper portion 107 of the primary support portion 101. Accordingly, the support surface 34 is in contact with the upper portion 107 when the child seat 3 rests on the primary support portion 101.As described above, the upper portion 107 may include a sliding surface 112 that may have a ring shape. Accordingly, in some embodiments, the support surface 34 may be configured to contact an annular sliding surface 112. As described above, the upper portion 107 of the primary support portion 101 may have a layered structure including an upper layer 110. This upper layer 110 may include a low friction material to keep friction between the child seat 3 and the primary support portion 101 low when the child seat 3 contacting the upper portion 107 is rotated about the rotation axis R 1. The support surface 34 of the child seat 3 does not include a low friction material in some configurations. The support surface 34 may comprise any suitable material, for example polyethylene (PE) material or other material. However, in some embodiments, the seat surface may also include a low friction material and the upper portion 107 may not include a low friction material.Example Locking Mechanism in Child Seat InterfaceThe child seat 3 may further include a locking mechanism 50 for detachably locking the child seat 3 to the primary support portion 101. In some embodiments, the locking mechanism 50 may be configured to engage behind the overhang portion 108 if the primary support portion 101 may include such an overhang portion 108. The lock mechanism 50 may include an engaging portion 51, 52 that is disposed to be radially movable into and out of the recess 31 so as to be capable of engaging with the circumferential recess 105 of the primary support portion 101. The recess 31 may be defined by the support surface 34 and a wall surface of a wall portion 45 extending from the support surface 34. The engaging portions 51, 52 may be disposed in openings of the wall portion 45.As shown in the configuration of FIG. 5, in some embodiments, the engagement portions 51, 52 may be provided on opposite sides of the recess 31. The engaging portions 51, 52 may be arranged to be movable toward and away from each other. The engaging portions 51, 52 are arranged at a distance from the support surface 34 so that when the engaging portions 51, 52 are in a locking position in which they project into the recess 31, a space for accommodating a portion of the primary support portion 101 is provided between the engaging portions 51, 52 and the support surface 34. For example, the latter space may be configured to at least partially receive the above-described overhang portion 108 of the primary support portion 101.Example Hidden Actuation Member for Actuating the Locking MechanismThe locking mechanism 50 may further include an operating member 53 for retracting the engaging portions 51, 52. The operating member 53 may be positioned on the child seat 3 in such a manner that it is accessible only when the child seat 3 is rotated to an unlocking orientation different from a forward or rearward orientation of the child seat 3 in some embodiments. Such an unlocking orientation of the child seat 3 is shown in FIG. 7. The operating member 53 may be provided at a lower portion of the child seat 3, for example, in a lower surface 68 of the child seat 3.FIG. 7 shows an unlocking orientation of the child seat 3. In the unlocking orientation, the main extension direction of the child seat 3, which corresponds to a viewing direction of a seated child, is oblique with respect to a main extension direction of the base 2, wherein the main extension direction of the base 2 can correspond to a longitudinal direction of the base 2 or a travel direction of the vehicle in which the base 2 is mounted. In the configuration as shown in FIG. 7, the main extension direction of the child seat 3 extends about 90° with respect to the main extension direction of the base 2. furthermore, the width of the lower portion of the interface 30 of the child seat 3 and the width of the base 2 are narrower than the length of the lower portion of the interface 30 of the child seat 3. Thus, when the child seat 3 is rotated to the orientation shown in FIG. 7, a front end portion, which may correspond to a foot end of the child seat 3, protrudes beyond a lateral edge portion of the base 2. As shown in FIG. 7, the operating member 53 may be provided at such a front end portion of the child seat 3 in the lower surface 68. Due to this configuration, the operating member 53 is accessible in the orientation shown in FIG. 7 and is exposed or hidden when the child seat 3 is rotated to a travel position in which the seat main extension direction and the base main extension direction are parallel.Example Locking Mechanism in Child Seat Interface PortionFurther details of the locking mechanism 50 will be described with reference to FIGS. 4 and 6. FIG. 4 shows a possible configuration of an engagement portion 51, 52. FIG. 6 shows an internal configuration of a mechanism for operating the engagement portions 51, 52, particularly the mechanism for operatively connecting the operation member 53 to the engagement portions 51, 52.As described above, the lock mechanism 50 may include an operating member 53. In the present configuration, the operation member 53 is configured to be pulled by a user. More specifically, the operation member 53 is configured to be pulled by a user in a main extension direction of the seat 3. The operating member 53 may be provided at an edge portion of the seat 3. Further, the actuating member 53 may be provided in, for example integrated with, the lower surface 68 of the seat 3. The operation member 53 may be disposed at an edge portion of the seat interface 30. Specifically, the operating member 53 may be provided at a foot end portion of the seat 3. The operation member 53 is configured to be gripped by a user. For this purpose, the actuating component 53 can have a cutout in order to receive the fingertip ends of a user. The operating member 53 is operatively connected to the engaging portions 51, 52. For this purpose, force transmission components 60 are provided, which couple the actuating component 53 to the engagement sections 51, 52. Each force transmission component 60 can comprise a Bowden cable.The power transmission member 60 may be part of a power transmission mechanism used to operatively connect the operating member 53 to the engagement portions 51, 52. The lock mechanism 50 may be configured such that a moving direction of the engagement portions 51, 52 extends transversely to a moving direction of the operation member 53. In the example shown in FIG. 6, the moving direction of the engaging portions 51, 52 is substantially perpendicular to the moving direction of the operating member 53. the locking mechanism 50 may be configured such that a pulling action applied to the operating member 53 results in movement of the engaging portions 51, 52 in a retracting direction, for example, movement of the engaging portions 51, 52 away from each other in opposite directions. The engaging portions 51, 52 may be biased in the locking direction by an urging member 67. In the configuration shown, the urging member 67 may be configured to directly apply an urging force to the engagement portions 51, 52. However, it is also possible to implement configurations in which the urging force of the urging member is indirectly applied to the engagement portions 51, 52 by a force transmission member, for example, by the above-described force transmission member 60. In this case, however, the force transmission member may be provided as a rigid member, for example, a rod or a rod, so as to be able to transmit a sufficiently high urging force to the engagement portions 51, 52.In the configuration as shown in FIG. 6, it is shown that the engaging portions 51, 52 may be disposed movably with respect to a supporting portion 65. The support portions 65 may be configured to appropriately hold and guide the power transmission member 60 so as to enable proper connection with the engagement portions 51, 52 that enables sufficient power transmission. The support portions 65 each have guide portions 63, 64. The guide portions 63, 64 are configured to securely hold the power transmission members 60. In the configuration as shown in FIG. 6, the power transmission members 60 are Bowden cables and the guide portions 63, 64 are configured to hold the Bowden cables with a predetermined curvature that enables optimum function of the Bowden cables.The support portions 65 may be configured symmetrically so that they can be used on opposite sides of the recess 31. For this purpose, the support portions 65 may have two guide portions 63, 64, although only one guide portion is required for operating the engagement portions 51, 52. By using such a symmetrical structure, it is possible to reduce the manufacturing cost because the support portions 65 can be used at different positions. The urging members 67 may be supported at one end on an inner surface of the support portions 65, and may be supported at an opposite end on the engagement portions 51, 52. Accordingly, the urging members 67 can be sandwiched between the support portions 65 and the engagement portions 51, 52.As shown in the configuration of FIG. 6, an end portion of the Bowden cable 60 may be coupled to a central portion of the engagement portions 51, 52. In this case, two urging members 67 may be provided on opposite sides of a connected Bowden cable. In this way, proper application of force to the engagement portions 51, 52 is possible without causing tilting movement of the engagement portions 51, 52. A first end section 61 of the force transmission component 60, in the present case a Bowden cable, is coupled to the actuating component. A second end portion 62 of the power transmission member 60 is coupled to an engagement portion 51, 52. Since the support portions 65, the engagement portions 51, 52, and the power transmission members 60 are identically configured, an operation of the operation member 53 results in simultaneous operation of the engagement portions 51, 52 to the same extent.One possible configuration of the engaging portions 51, 52 is shown in FIG. 4. The engaging portions 51, 52 may each include a locking member 54 that may be provided by a rigid main body. The locking member 54 may include guide portions 59 protruding from lateral sides of the locking member 54. At a rear end portion, the locking member 54 may include a recess 57 for accommodating an end portion of the power transmission member 60 and an opening 58 that allows the power transmission member to be guided into the recess 57. A front end portion of the locking member 54 may form an engaging portion of the locking member 54. The engagement portion may include a locking surface 55 and optionally a guide surface 56. The locking surface 55 is oriented in the upward direction so as to be capable of coming into contact with the overlapping portion 108 of the primary support portion 101, for example.The guide surface 56 may be oriented in a downward direction, for example away from the support surface 34, when the engagement portion 51 is mounted at the intersection 30 of the seat 3. The guide surface 56 is chamfered and configured to contact an outer edge portion of an upper portion 107 of the primary support portion 101. The guide surface 56 may be configured such that when coming into contact with the upper portion 107 of the primary support portion 101 upon mounting the seat 3 to the primary support portion 101, a urging force is generated that urges the engagement portions 51, 52 in a retracting direction when the child seat 3 is moved relative to the primary support portion 101 in a direction opposite to the first direction D 1. In this manner, movement of the engaging portions 51, 52 to a retracted position is automatically effected by pushing the guide surface 56 onto the upper portion 107. More specifically, the guide surface 56 is configured to slide on an outer periphery of the upper portion 107, and due to the chamfering of the guide surface 56, the engagement portions 51, 52 are urged toward the retracted position. Once the engaging portions 51, 52 have passed the overhang portion 108, they are free to engage the circumferential recess 105. Then, due to the presence of the urging members 67, the engaging portions 51, 52 are automatically engaged with the circumferential recess 105. Accordingly, it is not necessary for a user to operate the operation member 53 for inserting the child seat 3 on the primary support portion 101.Example child seat with chamfered insertion opening in the interface sectionFurther, as illustrated in FIG. 5, the recess 31 of the child seat 3 may be configured with an inclined circumferential wall portion 44 at an opening end portion of the recess 31. In this inclined circumferential wall portion 44, an outer diameter of the recess 31 is reduced from an opening toward the support surface 34 at least by a predetermined distance. In other words, in the opening end portion of the recess 31, the outer diameter of the recess can be expanded to a diameter larger than the diameter of the upper portion 107 of the primary support portion 101. With such a configuration, mounting of the seat 3 on the primary support portion 101 is facilitated because the opening for accommodating the upper portion 107 is enlarged. Further, such a structure provides a centering function because the seat 3 is automatically centered with respect to the primary support portion 101 by sliding contact of the inclined circumferential wall portion 44 with the upper portion 107 of the primary support portion 101.Example Configuration of Secondary Support PortionAs illustrated in FIGS. 1 and 2, but also in the configuration of FIG. 82, the base 2 may include a secondary support portion 102, 103. In this exemplary configuration, two secondary support portions 102, 103 may be provided. A first secondary support portion 102 may be provided in a front end portion of the base 2. A second secondary support portion 103 may be provided in a rear portion of the base 2. The secondary support portions 102, 103 may be radially spaced apart from the primary support portion 101. Each of the secondary support portions 102, 103 may be configured to receive a retaining portion 32, 33 of a child seat 3. In this connection, reference is made to Figures 5 and 7, which show possible configurations of retaining portions 32, 33 of the child seat 3. The function and configuration of the retaining portions 32, 33 will be described in more detail later.At least one secondary support portion 102, 103 may be configured to receive the retaining portion 32, 33 of the child seat 3 by rotating the child seat 3 about the rotation axis R 1 after the child seat 3 is seated on the primary support portion 101. Accordingly, the secondary support portion 102, 103 and the retaining portion 32, 33 may be configured such that the retaining portion 32, 33 can be inserted into the secondary support portion 102, 103 only rotationally. Each secondary support portion 102, 103 may be configured to limit tilting movement of the child seat 3 about a second rotation axis R 2 extending perpendicular to the rotation axis R 1.Example Settling ZoneThe secondary support portions 102, 103 and the retaining portions 32, 33 of the child seat 3 may be configured such that insertion of the child seat 3 on the base 2 within a predetermined landing zone is possible. The landing zone can be seen as an angular range a in which the child seat 3 must be aligned to couple it to the base 2. The landing zone can also be seen as an angular range α in which the retaining portions 32, 33 must be positioned to allow the child seat to be inserted onto the primary support portion 101. Within this angular range, the retaining portions 32, 33 are oriented such that they do not overlap with the secondary support portions 102, 103 and can pass laterally through the secondary support portions 102, 103 when viewed from above. Such a settling zone is shown in Fig. 53. The angle range may be greater than 90° on each lateral side of the primary support portion 101. The range may be greater than 100°, for example 112°.Example Base with Play Removal in the Secondary Support PortionAt least one secondary support portion 102, 103 may be configured to apply a downward urging force to an inserted retaining portion 32, 33. At least one secondary support portion 102, 103 may comprise an urging member 609, for example a leaf spring 610, as shown for example in Figure 9. The urging member 609 is provided to apply an urging force to the retaining portion 32, 33 in a second direction D 2 opposite to the first direction D 1 when the retaining portion 32, 33 is accommodated in the secondary support portion 102, 103.Example Arrangement for Preventing Misoperation / Rotation LockingIn some embodiments, an insertion geometry of at least one secondary support portion 103 may be mechanically encoded to block the child seat 3 from being positioned in an undesirable orientation. In particular, in some embodiments, the insertion geometry of at least one secondary support portion 103 may be mechanically encoded to block the child seat from being positioned in a forward orientation. For example, the insertion geometry may be such that only a retaining portion 32, 33 having a specific shape is allowed to be accommodated in the secondary support portion 103.In FIG. 8, a possible mechanical coding of the rear secondary support section 103 is shown. In this example, the secondary support portion 103 may include a abutting portion 120. The abutting portion 120 is configured to limit rotation of the child seat 3 about the rotation axis R 1 toward a forward orientation. The abutting portion 120 is configured to contact a stop portion 35 provided on the child seat 3. In the embodiment, the abutting portion 120 may include abutting surfaces 121, 122. Each abutting surface 121, 122 is configured to contact stop portion surfaces 36, 37 provided on the stop portion 35 of the child seat 3, as exemplarily illustrated in FIG. 5. The abutting surfaces 121, 122 may be formed such that the stop portion 35 is urged in a second direction D 2 opposite to the first direction D 1 when the stop portion 35 is pressed against the abutting portion 120 upon rotation of the child seat 3. In the configuration as shown in FIG. 8, the abutting surfaces 121, 122 are inclined.At least one secondary support portion 102 may be configured such that rotation of the child seat 3 about the rotation axis R 1 is automatically locked when the child seat 3 reaches a rearward orientation when rotating the same, for example, when rotating the same about the primary support portion 101.Example Base Allowing Forward Alignment by Manual ActionIn some embodiments, at least one secondary support portion 102 may be configured such that the child seat 3 is normally prevented from achieving the forward orientation and is rotatable to the forward orientation only upon actuation of an actuating member 119 by a user. The operating member 119 may be provided as shown in FIGS. 1 and 2, for example.A blocking portion may be provided which is movable between a blocking position and a release position. The blocking portion may be biased toward the blocking position. In the blocking position, the blocking portion provides a stop for the child seat 3. In the blocking position, the blocking portion may protrude into a rotational path of portions of the child seat, for example, a rotational path of the retaining portions. In the release position, the blocking portion is moved out of the way so as not to block rotation of the child seat 3. The blocking portion may be operatively connected to the operating member 119. Two operation members may be provided on opposite lateral sides of the base main body 20 and configured to be pressed inward in the lateral direction of the base 2 by a user.Example Base with Locking Mechanism with Blocking and Locking FunctionThe blocking function as described above may be implemented in a locking mechanism, for example in a locking mechanism 500 as disclosed herein. The lock mechanism can thus have a dual function of normally preventing the child seat from being rotated to a forward orientation unless a user permits such rotation by operating the operating member and the function of blocking the rotation of the child seat 3 when the forward orientation and / or the rearward orientation of the child seat 3 is established. The blocking portion may be a locking member 501 of a locking mechanism as described below. In other words, the locking member 501 of such a locking mechanism may also constitute the blocking portion. The operating member 119 may be a releasing member 502 of a locking mechanism 500.The locking mechanism 500 may be configured to block rotation of the child seat 3 about the rotational axis R 1, for example, by engaging a retaining portion of the child seat 3 when the seat is oriented in a desired orientation, for example, a forward orientation or a rearward orientation. The locking mechanism 500 may be configured to allow rotation of the child seat 3 about the rotational axis R 1 to orient the child seat 3 in a rearward orientation.The locking mechanism 500 may be configured to normally block rotation of the child seat 3 about the rotation axis R 1 in the forward orientation. The operating member 119 may be a push button.Some basic features of a possible configuration of the locking mechanism 500 are shown in FIGS. 11 and 12. Further optional features of the locking mechanism are described below with reference to Figures 31, 50 and 51.The locking mechanism 500 may be provided in the front secondary support portion 102. The locking mechanism 500 may include a locking member 501. The locking member 501 may be movable between a locking position in which it can engage with the retaining portion 32, 33 of the child seat and a release position in which rotation of the child seat 3 about the rotation axis R 1 is not blocked. In other words, in the locking position, a positive locking can be established between an inserted retaining portion and the locking component 501, whereas in the release position of the locking component 501, the locking component 501 is released from the retaining portion 32, 33.The locking member 501 may be biased by an urging member 503 as shown in FIG. 12. The locking component 501 can be prestressed in such a way that a movement of the locking component 501 in the direction of the release position is possible only counter to an urging force exerted by the urging component 503. In other words, a biasing force of the urging member 501 may act on the locking member 501 to move toward the locking position. The urging member 503 may be a spring.Example of Automatic Locking of Rear SeatThe locking mechanism 500 may be operably configured by an actuation force applied thereto by the child seat 3 to allow rotation of the child seat 3 to the rearward orientation without having to be manually operated, for example by pressing the actuation member 119 / release member 502. For example, the operation force may be generated by transmitting a rotational force applied to the child seat 3 into the operation force. In a configuration as shown in FIGS. 5 and 11, the operation force can be generated by slidably contacting a surface portion of the child seat 3 and a surface portion of the locking member 501. In general, the operating force for operating the locking mechanism 500, in particular for moving the locking member 501 to the release position, can be achieved by a pressing force exerted by the child seat 3 on the locking member 501.The locking member 501 may include a force receiving surface 504 extending such that the operation force can be generated by slidably contacting a force applying surface 42, 43 on the child seat 3 and the force receiving surface 504 when the child seat 3 is rotated about the rotation axis R 1 and contacts the locking member 501. The force receiving surface 504 may extend obliquely with respect to a longitudinal center plane of the locking member 501. The force receiving surface 504 may be inclined with respect to a moving direction of the locking member 501. Further details of the locking member 501 and the force receiving surface 504 will be described below with reference to FIG. 30.A possible configuration of force application surfaces 42, 43 on a child seat 3 is shown in FIG. 5. The force application surfaces 42, 43 may be provided on lateral sides of the retaining portion 32. The retaining portion 32 may be a retaining portion that is engaged by the locking mechanism 500 in the front secondary support portion 102 when the child seat is rotated to a rearward orientation. The force application surfaces 42, 43 are provided such that their imaginary extensions cross each other at a position located outside the retaining portion in the radial direction. In other words, the retaining portion 32 is tapered at its lateral sides in the direction of its free end portion. In this way, the force application surfaces 42, 43 are configured to push the locking member 501 away when the retaining portion 32 is rotated into the front secondary support portion 102.On the other hand, the child seat 3 may include abutment surfaces 39, 40 provided on lateral sides of the retaining portion 33. The retention portion 33 may be the retention portion that is received and engaged by the locking mechanism 500 when the child seat is oriented in a forward orientation. Such stop surfaces 39, 40 and / or the locking component 501 can be configured such that the above actuation of the locking component 501 by an actuation force exerted thereon by the child seat 3 is not possible. A rotation of the child seat 3 into the forward orientation without having to act manually is thus not possible. Instead, the stop surfaces 39, 40 and the locking member 501 are configured such that the locking member 501 acts as a stop and the forward orientation of the child seat 3 can only be achieved by first manually moving the locking member 501 to the unlocking or releasing position by operating the operating member 119 or releasing member 502.Exemplary Inner Structure of Front Secondary Support Portion and Locking MechanismFIG. 12 shows further details of a possible internal structure of the front secondary support portion 102 and the locking mechanism 500. In the configuration shown, the locking component 501 is provided in a supporting structure 512 such that it can move linearly. The support structure 512 may include two support portions 514 configured as catch portions similar to the catch portions 603, 604 of the support structure 600, as described in other parts of this description with reference to FIG. 8. The holding portions 514 may be configured in the form of a hook having a free end extending in the downward direction so as to be able to enclose a portion of the retaining portion from above. The support structure 512 may include a lower portion 518 configured to be attached to the main body of the base 2. Further, the support structure 512 may include two wall portions 520, 522 extending substantially perpendicularly from the lower portion 518 in an upward direction from lateral end portions of the lower portion 518. The holding portions 514 are provided in upper end portions of the wall portions 520, 522. The locking member 501 is disposed between the wall portions 520, 522. Further, the locking member 501 is disposed such that the engaging portions 505, 506 and the holding portions 514 face in the same direction, for example, toward the primary support portion 100 of the base 2.As already mentioned above, the locking mechanism 500 may comprise a release member 502, also referred to as an actuation member 119. In particular, the locking mechanism 500 may include two release members disposed on opposite sides of the locking member 501, although only one of the release members will be described below. Accordingly, in some configurations, two release members 502 or actuation members 119 may be provided for actuating a single locking member 501. The release member 502 is operatively connected to the locking member 501. The release member 502 may include a power transmission portion 540. The force transmitting portion 540 is coupled to the lock member 501 by a member 546. The power transmission portion 540 extends through an opening 521 provided in the wall portion 521. The release member 502 is configured to be linearly movable along an extending direction of the power transmission portion 540.The force transmission portion 540 may be formed straight. The release member 502 may include an urging member 542, for example, a spring. The urging member 542 may be provided such that one end of the urging member 542 is supported to cooperate with the releasing member 502, and another end of the urging member 542 is supported against the main body of the base 2. The urging member 542 is arranged to bias the release member 502 toward a locking position. Generally, the release member 502 is configured to be moved between the locking position and a release position. The release member 502 is coupled to the locking member 501 such that the locking member 501 is positioned in the release position when the release member 502 is in the release position and that the locking member 501 is positioned in a standby position as described in other parts of this specification but is movable to a locking position when a release member 502 is in the locking position.Additional details of the locking mechanism and its actuation by means of the release member 502 will be described with reference to Figures 50 and 51. As mentioned above, the force transmitting portion 540 is coupled to the lock member 501 by a link 546. The member 546 may have a first end portion 548 and a second end portion 550. The first end portion 548 is rotatably and slidably held in one of two guide slots 528 provided in the rear portion of the lock member 501. The guide slots 528 can extend parallel to one another and in the main extension direction of the locking component 501. The second end portion 550 may be hingedly coupled to the free end portion of the force transmitting portion 540. The second end portion 550 may include a cylindrical protrusion slidably received in an opening of the power transmission portion 540.FIG. 50 shows a configuration in which the release member 502 is in the locking position, and FIG. 51 shows a configuration in which the release member 502 is in a release position. As can be seen from the latter figures, the first end portion 548 of the link 546 is rotated about the second end portion 550, while the second end portion 550 is simultaneously translated towards the locking member 501 when the release member 502 is moved from a locking position as shown in Figure 52 to a release position as shown in Figure 51. Because the first end portion 548 is slidably retained in a slot 528, the locking member 501 is movable relative to the first end portion 548 when the release member 502 is in a locking position. In this way, it is possible to press the locking member 501 toward the release position by applying force to the locking member by a force application surface of a retaining portion as described in other parts of this specification.As can be seen from the above, a locking mechanism 500 may be provided, which may comprise two separate release members 502 or actuating members 119 connected to a single locking member 501. Such a locking mechanism 500 may be configured to allow rotation of the child seat 3 to a forward orientation only upon manual actuation of one of the two separate release members 502, and may additionally be configured to block rotation of the child seat 3 from the forward orientation and / or the rearward orientation once the forward orientation or the rearward orientation is achieved.Example Holding Structure in Secondary Support PortionAs illustrated in FIGS. 9 and 10, the base may include a support structure 600 for blocking a restraining portion 32, 33 from lifting off the base 2 to prevent a rotational movement of the child seat 3 in the event of an accident. The support structure 600 may be provided at least partially in a secondary support portion 102, 103. In some embodiments, the secondary support portion 102, 103 may include the support structure 600 or at least portions of the support structure 600.The support structure 600 may include one or more holders 601, 602. The holder 601, 602 may include a catching portion 603, 604 that may have a hook shape. Each retainer may be configured to receive one of the retaining portions 32, 33. In some configurations, the brackets 601, 602 may be force-transmittingly coupled to a coupling portion 202 configured to be engaged with a mounting structure 96 in the vehicle seat 90.The coupling portion 202 may be provided on a coupling assembly 200 or may be a portion of a coupling assembly as described later. The coupling arrangement 200 may comprise a connector, for example a coupling arm, and the coupling portion 202 may be provided in a free end portion of such a connector. The coupling portion 202 may be supported on the base 2 to be adjustable or movable on the coupling assembly to enable tensioning of the base 2 to the vehicle seat 90.As shown in FIG. 10, each bracket 601, 602 may be force-transmittingly coupled to the coupling portion 202 via a force transmission path including rigid force transmission members 605, 606, 607. The force transmission members may be made of metal to enable a safe force transmission of high forces. At least one force transmitting member may include a coupling portion supporting frame 606, 607. The coupling portion support frame 606, 607 may be configured to support a connector, for example a coupling arm, comprising the coupling portion 202, for example an isofix arm. Accordingly, in some embodiments, the coupling portion support frame may also be considered an isofix arm support frame.The coupling portion support frame 606, 607 may include a U-shaped housing having upwardly extending sidewalls. The coupling portion 202 may be supported on the coupling portion support frame 606, 607. Each bracket 601, 602 may be coupled to the coupling portion support frame 606, 607 by a coupling member 605, which in the configuration shown is a rod 608. A particularly advantageous force transmission can be achieved if the number of force transmission members is small. For example, each bracket 601, 602 may be coupled to the coupling portion support frame 606, 607 only by a single coupling member 605. The coupling member 605 may be directly coupled to the coupling portion support frame 606, 607, for example directly to the two upwardly extending walls of the U-shaped housing of the coupling portion support frame 606, 607.Example Tensioning Mechanism for a BasePossible features of a clamping mechanism 400 for a base 2 are described below. A base 2 for a child restraint system 1 may include such a tensioning mechanism 400 in addition to or as an alternative to the mechanisms and features of a base 2 for a child restraint system described herein.The tensioning mechanism 400 may be configured to generate a biasing force to urge the base 2 onto the vehicle seat 90 once the base 2 is operatively connected to a mounting structure 96 of the vehicle via a coupling assembly 200.FIG. 1 shows an arrangement in which a clamping mechanism 400 is provided on the base 2. The base 2, as shown in FIG. 1, may be coupled to the vehicle mounting structure 96 via a coupling assembly 200. The tensioning mechanism 400 may be configured to apply a force to the coupling assembly 200.The coupling arrangement 200 may include features as already described above and / or features as described further below. For example, the coupling assembly 200 may include a coupling portion 202 configured to be releasably engageable with the mounting structure 96 on the vehicle. The attachment structure on the vehicle may be a bracket, for example, an isofix attachment structure bracket. The coupling assembly 200 may include one or more connectors 204, 206. The connector can be formed as a coupling arm or can comprise it. Each of the connectors 204, 206 may include the coupling portion 202 described above. In some embodiments, the connectors 204, 206 may be configured as isofix system connectors that allow the base 2 to be secured to the seat 90 using an isofix mounting structure. However, it should be appreciated that other mechanisms and features may be used to couple the base 2 to the vehicle seat 90. For example, it is possible to use existing components of a seatbelt system of the vehicle to couple the base to the vehicle seat 90, for example, the seatbelt and / or a seatbelt latch. The connectors 204, 206 can be connected to one another by means of a connecting section, for example by means of a strap or a rigid component. The tensioning mechanism 400 may be configured to apply a force to the connectors 204, 206 and / or to such a connection portion, for example a pulling force.The tensioning mechanism 400 may be configured to generate an urging force for urging the base 2 toward the vehicle seat 90 after the base 2 is operatively connected to the mounting structure 96. In other words, the base 2 may be configured to be first coupled to the mounting structure. Thereafter, the clamping mechanism 400 may be operated to generate the urging force for urging the base 2 onto the vehicle seat 90. The use of a tensioning mechanism 400 enables the base 2 to be tightly tensioned against the vehicle seat 90.Generally, for these and all other embodiments, the base 2 may also be an integral portion of the child seat 3 unless it is specifically described that a child seat 3 may be removably or detachably mountable to the base 2. The base need not necessarily be a discrete part. On the contrary, the base 2 may also be an integral part of the child seat 3, in other words, the child seat 3 and the base 2 may not be detachably coupled.The tensioning mechanism 400 may be configured to generate the urging force to urge the base 2 onto the vehicle seat 90, and to generate a tension force on the attachment structure 96 or on components of the seatbelt system of the vehicle. Accordingly, by actuating the tensioning mechanism 400, the biasing force may be generated by applying a tension force to the seatbelt system attachment structure or components via the established operative connection between the base 2 and the attachment structure 96 or to seatbelt system components.The clamping mechanism 400 may include an actuation member 402. The actuator 402 may include or be configured as a lever 404. The tensioning mechanism 400 may be configured such that a user may generate the urging force by repeatedly reciprocating the operating member 402 of the tensioning mechanism 400. In other words, the clamping mechanism 400 may be configured such that the urging force for urging the base 2 toward the vehicle seat 90 may be generated by applying a pump-like action to the operating member 402.As already mentioned above, the base 2 may include a coupling portion 202 for fixedly coupling the base 2 to the attachment structure 96. Further, in some configurations, the base 2 may include an anti-rebound portion 300 configured to be contacted with a seat back 92 of the vehicle seat 90 to limit at least rotational movement of the base 2 toward the seat back 92 in a crash situation.In some configurations, the tensioning mechanism 400 may be configured to decrease a distance between the anti-rebound portion 300 and the coupling portion 202. For example, in some configurations, the distance between the anti-rebound portion 300 and the coupling portion 202 may be reduced by moving the coupling portion 202 relative to the anti-rebound portion 300. In some configurations, the distance between the anti-rebound portion 300 and the coupling portion 202 may be reduced by moving the anti-rebound portion 300 relative to the coupling portion 202. Accordingly, the distance can be reduced by moving the anti-rebound portion 300 and the coupling portion 202 relative to each other. It is also possible to provide a configuration in which both the anti-rebound portion 300 and the coupling portion 202 are moved relative to the main body 20 of the base and toward each other, for example, the anti-rebound portion 300 away from the main body 20 and the coupling portion 202 toward the main body 20.Example Reciprocating MechanismFIG. 1 shows a configuration in which the base 2 may include a coupling portion 202, an anti-rebound portion 300, and a clamping mechanism 400. The tensioning mechanism 400 is configured such that the user can reduce the distance between the anti-rebound portion 300 and the coupling portion 202 by repeatedly reciprocating the operating member 402. Hereinafter, details of a possible configuration of a clamping mechanism 400 in which a urging force can be generated by repeatedly reciprocating an operation member 402 will be illustrated with reference to the figures.The basic general function of a possible configuration of the clamping mechanism 400 will be described with reference to FIGS. 1, 15 and 16. The operating member 402 is force-transmittingly coupled to the coupling portion 202. In the configuration shown, the actuator 402 is a lever 404. The lever 404 can be a curved lever 404, in particular a U-shaped lever. In the configuration shown, the lever 404 is U-shaped and is held at its free end rotatable about a rotation axis P 1. The rotation axis P 1 may extend in the transverse direction C of the base 2. For example, in some embodiments including the primary support portion 101 as described in other parts of this specification, the lever 404 may be supported on opposite sides of a primary support portion 101. Accordingly, the lever 404 may be rotatable toward a front end portion 4 of the base 2 and back toward a rear end portion 5 of the base 2.The lever 404 may be movable between a stowed position as shown in FIG. 1 and an extended position as shown in FIG. 15. In the storage position, the lever 404 may be in a position where it is accommodated in the base so as not to protrude beyond an upper surface portion 118 of the base 2. For this purpose, a recess may be arranged in the upper surface section 118 of the base 2. The recess may have a shape corresponding to the shape of the lever 404 such that the lever 404 may be received in the recess when in the stowed position. For example, the recess and the lever 404 may be shaped such that, in the stowed position, an upper surface of the lever 404 and the upper surface portion 118 are substantially flush such that a transition between a lever surface and an upper surface of the upper surface portion 118 is substantially seamless. A recess 22 may be provided in the upper surface portion 118 that allows the actuator 402 to be engaged when in the stowed position. The recess 22 may be integrally formed with the recess for housing the lever 404 in the storage position. In other words, the recess for accommodating the operating member 402 in the storage position may be widened at a predetermined portion, so that at least in such a widened portion, the lever is not closely accommodated in the recess but can be gripped by a user.As shown in FIG. 16, the lever 404 can be moved back and forth as indicated by two arrows. This in turn leads to the described distance reduction between the coupling section 202 and the anti-rebound section 300. In the configuration of FIG. 16, the coupling portion 202 is configured to be movable toward and away from the anti-rebound portion 300 by the operation of the lever 404. For example, the coupling portion 202 may be translationally movable in the moving direction L 1. In other words, the coupling portion 202 can be retracted toward the main body 20 of the base 2.Accordingly, as can be seen from FIG. 16, a configuration may be provided in which the clamping mechanism 400 is configured to move the coupling portion 202 relative to the anti-rebound portion 300. In particular, the clamping mechanism 400 may be configured to translate the coupling portion 202, for example, in the longitudinal movement direction L 1.As already mentioned above, it is also possible to provide a clamping mechanism 400 configured to move the anti-rebound portion 300 relative to the coupling portion 202. Such a configuration is shown in FIG. 26. In the configuration shown, the anti-rebound portion 300 may be coupled to the main body 20 of the base 2 so as to be movable toward and away from the main body 20. Accordingly, a distance between the anti-rebound portion 300 and the coupling portion 202 can be reduced by moving the anti-rebound portion 300 closer to the coupling portion 202. In such a configuration, the main body 20 of the base 2 may remain stationary with respect to the coupling portion 202. In other words, the main body 20 and the coupling portion 202 may be disposed at a predetermined fixed distance such that the operation of the clamping mechanism 400 does not change the position of the main body 20 relative to a fixing structure 96 to which the coupling portion 202 is coupled. In contrast, after the base 2 has been coupled to such a mounting structure 96, the anti-rebound portion 300 may be moved toward the seat back of the vehicle seat 90 and away from the main body 20 by actuating the tensioning mechanism 400. The tensioning mechanism 400 may be configured to translate and / or rotate the anti-rebound portion 300 with respect to the main body 20. To illustrate this, the upper left smaller illustration in FIG. 26 illustrates a translation movement of the anti-rebound portion 300 and the right upper smaller illustration illustrates a configuration in which the anti-rebound portion 300 is moved by rotation about the main body 20 using a rotation arm.Example Clamping Mechanism with Ratchet MechanismIn embodiments including a tensioning mechanism 400, the actuator 402 may be force-transmittingly coupled to a movable portion that generates the urging force, for example, the coupling portion 202 or the anti-rebound portion 300. A mechanical device that allows a force to be transmitted to the movable portion only in one direction while preventing a transmission of force in the opposite direction may be provided. For example, a ratchet mechanism 410 may be provided, for example, in the force transmission path between the operating member 402 and the coupling portion 202 that allows a torque applied to the operating member 402 to be transmitted only in the tightening direction. For example, the ratchet mechanism 410 may be provided to force-transmittingly couple the actuating member 402 to an output member 422, for example an output shaft, the output member 422 in turn being force-transmittingly coupled to a coupling assembly 200 having the coupling portion 202 as a movable portion.For example, as shown in FIGS. 17 and 18, the operation member 402 and the output member 422 may both be provided to be rotatably movable about the rotation axis P 1. The output member 422 may be accommodated in end portions of the operation member 402. More specifically, according to the configuration, the output member 422 may extend through the free end portions of the operation member 402 in the direction of the rotation axis P 1. The operating member 402 may be held on the output member 422. In the free end portions of the operating member 402, a ratchet mechanism 410 configured to couple the operating member 402 to the output member 422 may be provided. The ratchet mechanism 410 may be configured to allow movement of the actuation member 402 relative to the output member 422 in one direction and lock movement of the actuation member 402 to the output member 422 in the opposite direction.In the configuration shown, the ratchet mechanism 410 may be configured such that when the actuation member 402 is moved from a lowered position, as shown in FIG. 17, to an extended position, as shown in FIG. 18, a rotational force input to the actuation member 402 is transmitted to the output member 422. Accordingly, when the operating member 402 is moved in the latter-described direction, rotation of the operating member 402 is transmitted to corresponding rotation of the output member 422. In other words, in the latter moving direction, i.e., in the tightening direction, the ratchet mechanism 410 couples the operating member 402 and the output member 422 to be integrally moved.Specific details of a possible configuration of the ratchet mechanism 410 will be described with reference to FIGS. 19 and 20. FIG. 19 is a sectional view of the end portion of the operating member 402 and the ratchet mechanism 410. It is noted that the ratchet mechanism 410 may be completely hidden within the end portions of the actuation member 402, according to some configurations.The ratchet mechanism 410 may include a locking member 412. The locking member 412 may be movably supported in the operating member 402 so as to be movable toward and away from the rotation axis P 1. Accordingly, the locking member 412 may be movable in the radial direction with respect to the output member 422. The locking component 412 can be spring-loaded by means of an urging component 418, for example by means of a spring 420. In particular, according to the configuration shown, the locking member 412 may be biased by the urging member 418 toward the rotational axis P 1 and the output member 422 respectively.The ratchet mechanism 410 may include an engaging portion 423 provided to be integrally movable with the output member 422.For example, the engagement portion 423 may include a gear 424. The engagement portion 423 may be an integral portion of the output member 422 or may be rotationally locked to the output member 422. In the configuration illustrated in FIG. 19, the engaging portion 423 is configured as a gear 424 rotationally locked to the output member 421 by a connecting pin (not shown).The locking member 412 may be configured to releasably engage the engagement portion 423. The locking member 412 may be held in the operating member 402 to be movable only translationally. When the operating member 402 is rotated, the locking member 412 is rotated accordingly. Therefore, rotation of the operation member 402 can be transmitted to the output member 422 when the lock member 412 is engaged with the engagement portion 423.The locking member 412 may include a front end portion 416 specifically configured to engage the engagement portion 423. For example, the front end portion 416 may be configured to engage teeth 426 of the gear 424. The teeth 426 according to the configuration shown are shaped to allow for clamping (clockwise in FIG. 19 ) whereas movement of the actuation member 402 in an opposite direction (counter-clockwise) relative to the output member 422 is possible. Accordingly, ratchet mechanism 410 is configured to allow for force transfer in only one direction, clockwise in FIG. 19.As mentioned previously, the output member 422 may be force-transmittingly coupled to the coupling portion 202. Rotation of the output member 422 may be transferred into linear movement of the coupling portion 202. A configuration may be provided in which a distance between the coupling portion 202 and the rotation axis P 1 is reduced when the clamping mechanism 400 is operated. In other words, the movement of the actuating member 402 in the clockwise direction in FIG. 19 about the rotational axis P 1 can be transferred into a retracting movement of the coupling portion 202 in the direction of the rotational axis P 1.Example Clamping Mechanism with Torque LimiterIn some configurations, the output member 422 may be directly coupled to a driven portion 210 of the coupling assembly 200 via a force output member 470. The power output member may be a drive pinion or gear 472. The output member 422 may be coupled to the force output member 470 via a torque limiting mechanism 490. By using such a torque limiting mechanism 490, a predetermined maximum torque transmitted to the coupling assembly 200 may be preset. Such a configuration may provide feedback to a user that a predetermined maximum tightening force is achieved.Various configurations of a torque limiting mechanism 490 may be realized. An example is given in Fig. 22. The example torque limiting mechanism 490 may include a housing 491 locked to the output member 422 to be integrally rotatable with the output member 422. Such a locking can be provided by means of a pin which couples both components. The housing 491 may be cylindrical and may define a space between the output member 422 and an inner wall of the housing 491. Such space is available to accommodate an urging member 492 and at least partially an engaging member 493 therein. The engaging member 493 is held in the housing 491 to be movable along the output member 422. The urging member 492 is provided between the engagement member 493 and a housing portion to bias the engagement member 493 in the engagement direction.The engagement member 493 is configured to be engaged with a receiving member 495, which may be force-transmittingly coupled to the force output member 470 or may be an integral part of the force output member 470. The engagement member 493 may include protrusions 494 protruding in a direction along the extending direction of the output member 422. The receiving member 495 may include recesses 496 configured to receive the protrusions 494 in a positive fit manner. Accordingly, when the protrusions 494 are received in the receiving member 495, positive locking in the rotational direction is achieved that allows rotation of the output member 422 to be transmitted to the force output member 470. The protrusions 494 and the recesses 496 may be configured such that the engagement member 493 may be forced out of engagement with the receiving member 495 when a torque introduced by the output member 422 into the torque limiting mechanism 490 exceeds a predetermined maximum torque. In this case, the engagement member 493 is pressed against a force of the urging member 492 in the releasing direction due to the geometries of the protrusions 494 and the recesses 496. A torque transmission can thus be interrupted.As mentioned above, the clamping mechanism 400 may be configured to transmit a clamping force to the coupling portions 202. In some configurations, for example, the configurations as shown in FIGS. 17 and 18, applying a tension force by the tension mechanism 400 to the coupling portions 202 may result in a retracting movement of the coupling portions 202, for example, toward the main body 20 of the base 2 or the main body 20 of the base. This retracting movement, in turn, may result in the generation of a compressive force exerted by the anti-rebound portion 300 on the seat back of the vehicle seat. Accordingly, when the clamping mechanism 400 is operated, the anti-rebound portion 300 is clamped to the seat back, which in turn results in the coupling portions 202 being subjected to a pulling force that pulls them in an opposite direction to the retracting direction, in other words, a pulling force in an extending direction.In order to prevent movement of the coupling portions 202 in the extending direction, configurations may be provided in which movement of the coupling portions 202 in the extending direction is restricted. One possible configuration is shown in Fig. 20. In this configuration, the coupling portion 202 is provided on a connector 204, for example, a coupling arm. The connector and / or coupling arm may be movable relative to a support structure 600 in a coupling portion support frame 606 of the support structure 600. The configuration as shown in FIG. 20 may be such that actuation of the tensioning mechanism 400, in other words clockwise movement of the lever 404, results in movement of the connector 204 in a retraction direction corresponding to rightward movement in FIG. 20.The connector 204 may include a locking portion 214 and the support structure 600 may include receiving portions 612. In the configuration shown, the receiving portions 612 have recesses provided at equal intervals in the moving direction of the connector 204. The locking portion 214 is configured to be releasably engageable with the recesses. An urging member (not shown) is provided to bias the locking portion 214 toward a locking position in which the locking portion 214 is engaged with a recess. Accordingly, once the connector 204 is in a position in which the locking portion 214 is aligned with a recess, the locking portion 214 will automatically enter the recess. In this way, a lock is provided between the support structure 600 and the connector 204 that prevents at least movement of the connector 204 in the extending direction, in other words, toward the left side in FIG. 20. In this way, once the coupling portion 202 is retracted to a specific position by an operation of the clamping mechanism 400, movement of the coupling portion 202 in the extending direction is prevented. In this way, the coupling portion 202 can be gradually retracted by exerting a reciprocating motion of the operating member 402.Example Tensioning Mechanism with Display Device (Pop-up Feature)In some embodiments, the child restraint system 1 may be configured to indicate to a user that an actuator for biasing the base 2 to a vehicle seat 90 is available. In other words, a system can be provided that prompts the user to use a specific operating member to generate a sufficiently high force that presses the child restraint system 1 onto the vehicle seat. For example, by creating sufficient contact pressure between an anti-rebound portion 300 and the seat back 92 of the vehicle seat 90, it is possible to provide resistance to rotation of the child restraint system toward the seat back 92 in a crash situation.A display device configured to display to a user when the operating member is ready for use for tensioning is described. In this connection, reference is made to Figs. 13, 14 and 23 to 25.Generally, the display device 450 may be provided on any suitable portion of the child restraint system 1. In some configurations, the display device 450 may be provided on the base 2 for a child restraint system 1. While a mechanical solution for a display device 450 is described below, it is noted that the display device may also be implemented electronically. Generally, the display device may be configured to provide a user with a visual and / or audible indication. A visual indication may include a visible movement of a particular part or parts, a visual indication on a display device, or an indication from a light source. An audible prompt may include a particular sound or voice message prompting the user to perform a particular action such as tensioning with the actuator. As a visual cue, the action to be performed by a user may be displayed on a display device 1000 as shown in FIGS. 13 and 14. Such a display device 1000 can show, for example, an animation about how specific sections of the child restraint system 1 are to be actuated by the user.The display device 450 may be provided in a base 2 including a coupling portion 202, an anti-rebound portion 300, and a tension mechanism 400. The coupling portion 202 may be configured to fixedly couple the base 2 to a mounting structure 96 of the vehicle, for example, a mounting structure 96 on a vehicle seat 90. The anti-rebound portion 300 may be configured to be brought into contact with a seat back 92 of the vehicle seat 90 to limit at least rotational movement of the base 2 towards the seat back 62 in a crash situation.The tensioning mechanism 400 may be configured to decrease a distance between the anti-rebound portion 300 and the coupling portion 202. Other configurations of the tensioning mechanism may be possible as long as the tensioning mechanism can be readily used to generate a force that presses the base 2 onto the vehicle seat 90. The clamping mechanism 400 may include an actuation member 402.The display device 450 may be configured to display to a user when the actuation member 402 is ready for use for tensioning. In the configuration shown in FIGS. 13, 14 and 23 to 25, the display device 450 may be configured to move the operation member 402 to a predetermined display position. In the example shown, the actuator 402 is a lever 404. An exemplary predetermined display position is shown in FIGS. 13 and 14, for example. The display position corresponds to a predetermined orientation of the operation member 402. As shown in FIGS. 13 and 14, the operation member 402 has been moved slightly upward from an accommodation recess provided in a main body of the base 2. The display device 450 may be configured such that movement of the actuating member 402 to this position is quickly effected upon satisfaction of a certain condition. Such a condition may include a status change in the coupling portion 202, for example, a status change of the coupling portion 202 from an unlocked state to a locked state in which the coupling portion 202 is releasably locked to the attachment structure 96.The tensioning mechanism may be configured such that, for actuating the same, the actuating member 402 is moved between a stowed position and a deployed position, for example in a reciprocating movement. In this connection, reference is made to the above-described possible configuration of a clamping mechanism 400, as already described in connection with other examples of exemplary configurations.The display device 450 may be configured to automatically move the operating member 402 to the predetermined display position when the coupling portion 202 engages the mounting structure 96. Additionally or alternatively, the display device may be configured to move the operating member to the predetermined display position when a distance between the coupling portion 202 and the anti-rebound portion 300 is decreased to a predetermined intermediate distance. Such a decrease in the distance between the coupling portion 202 and the anti-rebound portion 300 may be caused, for example, by pressing the base 2 toward the seat back 92 in a pressing direction P 1 with the coupling portion 202 engaged with the mounting structure 96.Example coupling assemblies 200 including the coupling portion 202 and configured to allow rearward movement of the coupling portion 202 into the main body of the base 2 when the coupling portion 202 is locked to the mounting structure 96 and the base is pressed toward the seatback 92 will be described later. Such configurations may include a retraction blocking portion or a second locking portion 216 that blocks movement of the coupling portion 202 in a retraction direction as long as the coupling portion 202 is not locked to the attachment structure 96. This retraction blocking portion or the second locking portion 216 may be operatively connected to the coupling portion 202 such that the retraction blocking portion 216 is automatically moved to an unlocking or releasing position when the coupling portion 202 is locked to the mounting structure 96.The display device 450 may include two cooperating portions 452, 454. For example, one of the two cooperation portions may be a toothed portion 452 and the other of the two cooperation portions may be a recessed portion 454. One of the cooperation portions may thus be a protruding portion and the other of the two cooperation portions may be a receiving portion. At least one of the cooperating portions 452, 454 may be movable relative to the other and the cooperating portions 452, 454 may be configured to releasably engage when the predetermined display position is reached. One of the two cooperation portions may be operatively connected to the operating member 402, and the other of the two cooperation portions may be provided stationary in the base, for example, in a structure of a main body 20 of the base. The two cooperating portions 452, 454 may be configured to restrict at least movement of the actuating member 402 out of and / or into the predetermined display position.One possible configuration is shown in Figs. 23 to 25. As illustrated in FIG. 23, a protruding portion 452 is provided on the operating member 402 at a position where the operating member 402 is coupled to the output member 422. The protruding portion 452 may be formed on an outer surface of a housing for accommodating members of the ratchet mechanism 410 described above. Accordingly, when the operation member 402 is rotated about the rotation axis P 1, the protruding portion 452 is moved on a circular path about the rotation axis P 1. The receiving portion or recessed portion 454 is provided in the main body 20 of the base 2 at a position where at least a portion thereof interferes with the protrusion 452 as it moves on the circular path. The receiving portion 454 may be configured as a protrusion having a central recess therein. The cooperation portions 452, 454 may be made of a material and / or configured to be easily deformable upon contact of the cooperation portions. Accordingly, the protruding portion 452 may contact the cooperation portion 455 during its movement along the circular path. In this position, further rotation of the actuating member 402 and integral further movement of the protruding portion 452 on the circular path is only possible upon application of a slightly increased force to the actuating member 402. When a predetermined force is exceeded, the protruding portion 452 may deform and move over an edge portion of the cooperating portion 454 until it reaches the central recess in the cooperating portion 454. This position of the operation member 402 and the cooperation portions 452 corresponds to a predetermined display position. In this position, the actuator 402 has only been slightly moved to a position and orientation as shown in Figures 13 and 14. Movement of the cooperation portion 452 into the central recess of the cooperation portion 454 may involve a click sound. When the operating member 402 is in the display position, as shown in FIG. 24, a user immediately recognizes that the operating member 402 is available for clamping purposes and can grasp the same.By applying a tension force to the operating member 402, the user can move the operating member 402 from the display position by further rotating the operating member 402, for example, clockwise as shown in FIG. 25. In this case, the protruding portion 452 disengages from the cooperation portion 454 and the operating member 402 may be used to execute a reciprocating motion for operating the clamping mechanism 400. Note that a force required to move the protruding portion 452 from the state as shown in FIG. 23 to the state as shown in FIG. 24 can be introduced into the operating member 402 by means of power transmission from the coupling portions 202 and via the ratchet mechanism 410. More specifically, the base 2 may be configured such that, when the coupling portions 202 are locked and a pressing force P 1 is applied as described above, the coupling portions 202 are moved in a retracting direction, resulting in application of a rotational force to the output member 422 due to an operative connection between the coupling portions 202 and the output member 422. Since the movement of the coupling portions 202 may correspond to a movement of the coupling portions during tensioning using the operating member 402, a rotational force applied to the operating member 402 from the output member 422 moves the operating member 402 in the tensioning direction, which means clockwise in the configuration shown in FIGS. 23 to 25.It is further noted that the configuration and position of the cooperation portions 452, 454 may be such that they contact each other on an outer side when the operation member 402 is positioned in the aforementioned storage position, as shown in FIG. 23. Such a configuration requires a slightly higher force for rotating the operation member 402, because the protruding portion 452 needs to pass a portion of the cooperation portion 454 by being subjected to slight elastic deformation. Therefore, the operating member 402 is more securely accommodated or held in the storage position and is less prone to vibration movement during travel of the vehicle. Accordingly, adverse rattle noise that may occur due to a vibrating operating member 402 can be avoided.Example Base with Release MechanismThe child restraint system 1 may include a release mechanism 700. For example, the base 2 of a child restraint system 1 may include the release mechanism 700. The release mechanism 700 may be configured to release the coupling portion 202 from the mounting structure 96. Additionally or alternatively, the release mechanism 700 may be configured to release a ratchet tensioning mechanism 400 to reduce a distance between an anti-rebound portion 300 and the coupling portion 202. The tensioning mechanism 400 may be a tensioning mechanism as described in connection with other configurations of a base 2 for a child restraint system 1 described herein. The release mechanism 700 may additionally or alternatively be configured to release movement of the coupling portion 202 relative to the anti-rebound portion 300. Accordingly, a release mechanism 700 may be provided that provides one or more of the last described functions.The release mechanism 700 may include at least one actuation portion 702, 704. In some configurations, the operating portion 702, 704 may be provided on the base 2 so as to be accessible only when a child seat 3 is removed from the base 2. In other words, a child seat 3 disposed on the base 2 makes the operating portion 702, 704 inaccessible. A possible configuration of a base 2 for a child restraint system 1 is illustrated in FIGS. 1, 17, 18 and 21. The base 2 of FIG. 1 may include a coupling portion 202 for releasably coupling the base 2 to a mounting structure 96 of the vehicle. The base may include the release mechanism 700. In the illustrated configuration, the release mechanism 700 may include any of the aforementioned features. More specifically, the release mechanism 700 is configured to release the coupling portion 202 from the mounting structure 96, is configured to release a ratchet tensioning mechanism 400, and is configured to release movement of the coupling portion 202 relative to the anti-rebound portion 300. By actuating the actuating section 702, 704 of the release mechanism 700, all of the latter functions are triggered.In some configurations, the operation portion 702, 704 is provided on an upper surface portion 118 of the base 2 at a position covered by an inserted child seat 3. Accordingly, in such configurations, the child seat 3 can form a cover member that covers the operation portion 702, 704.Additionally or alternatively, the base 2 may include a cover member movable between a cover position in which the cover member covers the operating portion and a release position in which the operating portion is accessible for operation. The cover member may be configured to be moved to the cover position when a child seat is inserted on the base. With such a configuration, it is possible to provide the operating portion 702, 704 at a position of the base 2 that is not covered by an inserted child seat 3, while still having the function of making the operating portion 702, 704 inaccessible once a child seat 3 is inserted on the base 2. A mechanism for moving the cover member may include a force receiving portion operatively connected to the cover member and configured to receive a force from the child seat 3 when inserted on the base 2, wherein actuation of the force receiving portion by the child seat 3 results in movement of the cover member to the cover position.Regardless of the above-described function of the release mechanism 700 that proposes to arrange the at least one actuation portion on the base 2 such that it is only accessible when a child seat 3 is removed from the base 2, the release mechanism 700 may additionally or alternatively comprise two actuation portions 702, 704, and the release mechanism 700 may be configured such that the release of the base 2 from the attachment structure 96 is possible only by actuating both actuation portions 702, 704. The detachment of the base 2 from the fastening structure 96 can be possible only by simultaneously or successively actuating both actuating portions 702, 704. FIG. 27 shows an example configuration in which two operating portions 702, 704 are laterally spaced apart from each other and provided on opposite sides of a primary support portion 101. As shown, a user must press both actuation portions 702, 704 to actuate the release mechanism. Exemplary positions of the two actuating portions 702, 704 are also illustrated in FIGS. 1, 13 and 15.When the base 2 includes a clamping mechanism 400 as described in combination with other configurations in the present disclosure, the release mechanism 700 may be configured to release the coupling portion 202 and the clamping mechanism 400 simultaneously. In other words, actuating the release mechanism 700 may release the coupling portion 202 and the tensioning mechanism 400.In some configurations, the operating portions 702, 704 may be provided on opposite sides of the primary support portion 101. Details of possible configurations of such a primary support portion 101 will be described in combination with other configurations as mentioned in the present disclosure. As shown in FIGS. 18 and 21, each actuator 702, 704 may include a coupling portion 706 to force-transmittingly couple the actuator 702, 704 to the coupling portion 202. In the illustrated configuration, the coupling portion 706 is configured to be coupled to an end portion of a force transmitting member. In this case, the coupling portion 706 is configured to be coupled to a Bowden cable. Accordingly, the coupling portion 706 may include a recess to receive an end portion of a Bowden cable wire. An opposing end portion of the Bowden cable wire may be coupled to the coupling portion 202, particularly to a locking member in the coupling portion 202 that allows or blocks movement of an engagement member engageable with the mounting structure 96. The force transmission member may be adjustable to allow adjustment of the force transmission from the actuation member 702, 704 to the coupling portion 702. Accordingly, the operating portions 702, 704 enable remote operation of the coupling portion 202 to unlock the same.The release mechanism 700 according to the illustrated configuration is configured such that upon actuation of the release mechanism 700, the tensioning mechanism 400 is deactivated by placing the tensioning mechanism 400 in a free-wheeling state. The tensioning mechanism 400 may include features and configurations as described herein with reference to other configurations and embodiments of the base 2 or the infant restraint system 1. The tensioning mechanism 400 may include an actuating member 402 that is force-transmittingly coupled to the coupling portion 202 by a ratchet mechanism 410. The release mechanism 700 may be configured to deactivate the ratchet mechanism 410 by transitioning the ratchet mechanism 410 to a free-wheeling state. The release mechanism 700 may include a power transfer mechanism 705 configured to transfer movement of the actuation portion 702, 704 into movement of the latch member 412 in a release direction D 5. By sliding the lock member 412 in this manner, locking between the operation member 402 and the output member 422 can be released.The power transmission mechanism 705 may include a power transmission member 710. The force transmitting member 710 may be configured to receive an operating force from a force applying portion 708 of the operating member 702, 704, and may be configured to move toward the locking member 412 upon receiving the operating force. The force transmitting member 710 may include a force applying surface 712 to contact a receiving portion 419 of the locking member 412. The force application surface 712 may be formed in the shape of an outer surface of a truncated cone to allow interaction with the force receiving portion 419 at various angular orientations of the actuation member 412. The force transmitting member 710 may be a sleeve extending about a rotational axis P 1 of the operating member 402, as illustrated in FIG. 22. Further, the power transmission member 710 may be slidably provided on the output member 422.The force transmission member 710 may include a force receiving surface 711, and the force applying portion 708 may include a force applying surface 709 contacting the force receiving surface 711. The operating portion 702, 704 may be configured to be rotatable about the rotation axis P 1 in the rotation direction D 3. The force receiving surface 711 and the force applying surface 709 may be configured such that the force transmitting member 710 is displaceable in a displacement direction D 4 along the rotation axis P 1 by a wedge action generated by a sliding contact between the force applying surface 709 and the force receiving surface 711. Each actuating portion 702, 704 may include a lever. The coupling portion 706 and the force applying portion 708 may be integrally formed on the operating portion 702, 704.In an alternative configuration, best seen in FIG. 106, the actuation portion 702, 704 may be operatively connected to or include a force application portion 708 that does not cause movement of a force transmitting member along the rotational axis, but is moved about the rotational axis P 1 or in a direction perpendicular to the rotational axis P 1. The force application portion may be or include a cam portion 713 that, when the operation portion 702, 704 is operated, is rotated about the rotation axis P 1 and applies a force to the receiving portion 419. The cam portion 713 may include a rising force application surface 712 facing outward from the rotation axis P 1 and toward the receiving portion 419. The receiving portion 419 is configured to be in sliding contact with the contact surface when the operating portion 702, 704 is operated and moved to a predetermined position. Due to the increasing force application surface 712, the distance of a contact position between the receiving portion 419 and the contact surface relative to the rotation axis P 1 increases upon operation of the operation portion 702, 704. In other words, the force applying surface applies a pressing force in the direction D 5 shown in FIG. 21 when being rotated about the rotation axis P 1 and moved relative to the receiving portion 419. The cam portion 713, the force applying portion 708 and / or an operating portion 703 of the operating member may be integrally formed in a single part.In some configurations, the coupling portion 202 may be configured to automatically move to an extended position when movement of the coupling portion 202 relative to the anti-rebound portion 300 is enabled by the release mechanism 400. The coupling portion 202 may be biased by an urging member 212 such as a coil spring in a direction away from the anti-rebound portion 300 as shown in FIG. 17, for example.The coupling portion 202 may be part of a coupling arrangement 200. The coupling arrangement may be configured in a manner as described herein with respect to other configurations and embodiments. The coupling assembly may include at least one connector 204, 206, for example a coupling arm supported on a support structure 600 and movable between an extended position and a retracted position. The at least one connector 204, 206 and the support structure 600 are configured to be releasably lockable to lock the coupling portion 202 at a plurality of different locking positions on the support structure 600.At least one connector 204, 206 may include a locking portion 214 and the support structure 600 may include receiving portions 612, such as shown in FIG. 18. The locking portion 214 may be configured to be releasably engageable with the receiving portions 612. The locking portion 214 may be arranged to be only translationally movable to establish the releasable engagement. The release mechanism 700 may be configured to release a latch between the connector 204, 206 and the support structure 600 to allow movement of the coupling portion 202 relative to the anti-rebound portion 300.As also shown in FIGS. 17 and 18, the coupling arrangement 200 may comprise two connectors 204, 206 which are supported by the holding structure 600 and each comprise a coupling portion 202. The connectors 204, 206 may be coupled to one another by means of a connection device 208, for example a rigid connection component. In this way, the two connectors, for example coupling arms, are integrally movable. The previously described urging member 212 may be arranged to apply an urging force to the connecting device 208. Accordingly, the urging member may be coupled at one end to the connection device 208.As already described above, the child restraint system 1 can have a sensor arrangement 800. For example, a base 2 for a child restraint system 1 can be provided, which has a sensor arrangement 800. The sensor arrangement 800 may include one or more sensors having specific sensing functions.Example Base with Magnetic Sensor in Primary Support PortionIn some embodiments, the sensor assembly 800 may include a seat detection sensor 802. As illustrated in FIG. 28, the seat detection sensor 802 may be provided at an upper portion of a main body 20 of the base 2, for example, at a primary support portion 101. The seat detection sensor 802 is configured to detect the presence of an inserted child seat 3 on the primary support portion 101. The primary support portion 101 may be configured as described above. For example, the primary support portion 101 may protrude from an upper surface portion 118 of the base 2 in a first direction D 1. Further, the primary support portion 101 may be configured to be detachably engaged by an engagement portion of an inserted child seat in a positive manner to block movement of the child seat in the first direction.The primary support portion may be further configured to support the child seat rotatably about a rotation axis R 1 extending parallel to the first direction D 1. The seat detection sensor 802 may be provided in an accommodation space 115 inside the primary support portion 101 as can be seen from FIGS. 3 and 32. FIG. 32 shows a configuration of a base in which the upper portion 107 of the primary support portion 101 is removed, thereby exposing the position of the seat detection sensor 802 in the primary support portion 101. In the exemplary configuration, a recess is provided in a reinforcement structure 124 such that material between the sensor 802 and any sensor detectable feature provided on a child seat 3 is not obstructed by a portion of the reinforcement structure 124. The sensor 802 may be a magnetic sensor, for example a Hall sensor.Example Child Seat Having a Sensor-Detectable FeatureAs mentioned previously, a child seat 3 may have a sensor detectable feature that may be detected by the seat detection sensor 802. Accordingly, a child seat 3 may be provided that is mountable on a base 2 and has at least one sensor detectable feature 46, 47. The sensor detectable feature may be a magnet and thus may be detectable by a magnetic sensor.The sensor detectable feature is shown in Figure 5. More specifically, FIG. 5 shows a configuration in which two sensor detectable features 46, 47 are provided at a lower portion of the child seat 3. As further illustrated in FIG. 5, the sensor detectable feature 46, 47 may be visible. For example, the sensor detectable feature 46, 47 may be provided at the lower portion so as not to protrude from a support surface 34 of the child seat 3. In particular, the sensor detectable feature 46, 47 may be mounted on an inner surface facing in the opposite direction of the support surface 34. The sensor detectable feature 46, 47 may be configured to trigger the seat detection sensor 802 as described above. Specifically, the sensor detectable feature is provided on the child seat 3 such that the seat detection sensor 802 detects the presence of the sensor detectable feature when the child seat 3 is correctly mounted and / or aligned on the base.In the configuration shown in FIG. 5, two detectable features 46, 47 are provided. Here, the two detectable features 46, 47 each have a magnet. The two detectable features 46, 47 are provided at the lower portion of the child seat 3 on opposite sides of a rotation center of the child seat 3. The sensor detectable features 46, 47 may be positioned on an imaginary straight line crossing the center of rotation of the child seat 3, wherein the imaginary straight line may be parallel to a longitudinal direction of the child seat 3 and perpendicular to a rotational axis defined by the interface 30 of the child seat 3, in particular in a front-rear direction.The sensor detectable features 46, 47 may be arranged at an equal distance from the center of rotation of the child seat 3. With such a configuration, a single seat detection sensor 802 can detect two seat orientations. In other words, such a configuration may be configured to detect a forward orientation of the child seat 3 and a rearward orientation of the child seat 3.Example Base with Twist Lock DetectionAdditionally or alternatively, the sensor assembly 800 may be configured to sense the status of a latch mechanism 500. The locking mechanism 500 may be configured as described in connection with other configurations and aspects of the present disclosure. For example, the sensor arrangement 800 may be configured to sense at least the presence of the previously described locking member 501 in the release position.An exemplary configuration in which the sensor assembly 800 is configured to detect various states of the latch mechanism 500 will be explained with reference to FIGS. 12, 30, and 31. The locking mechanism 500 may be configured to block rotation of an inserted child seat 3 about the rotation axis R 1. In the configuration, the locking mechanism 500 may include a locking member 501 movable between a standby position I, a locking position II, and a release position III.One possible configuration of the locking member 501 is shown in FIG. 30. FIG. 12 shows a possible arrangement of the locking member 501 in the locking mechanism 500. FIG. 30 is a perspective view of the locking member 501 according to an example. The locking member 501 may have a plate-like appearance. More specifically, the locking member 501 may have a plate-like shape having a step between a front portion and a rear portion. Accordingly, a front end portion of the locking member 501 may be offset with respect to a rear portion of the locking member 501.In the front end portion of the locking member 501, two engaging portions 505, 506 are provided. Both engagement portions 505, 506 protrude in the main extension direction of the locking member 501. A recess 507 is provided between the engaging portions 505, 506. Accordingly, the engaging portions 505, 506 can be considered as teeth protruding in the main extension direction at the front end portion of the locking member 501. The recess 507 is bounded in the lateral direction by the engagement portions 505, 506, more specifically by wall portions of the engagement portions 505, 506 facing each other.Force-absorbing surfaces 504, as already described above, can be provided on lateral outer sides of the engagement portions 505, 506, more precisely on a side of the engagement portions 505, 506 opposite the cutout 507. The force-absorbing surfaces 504 can be beveled in the direction of the free ends of the engagement sections 505, 506. Accordingly, the front end portion of the locking member 501 may be chamfered at both lateral sides. The force receiving surfaces 504 may be configured such that their imaginary extensions cross each other in a region between the rotation axis R 1 defined by the primary support portion 100 and the locking member 501. The force-absorbing surfaces can be planar surfaces. However, it is also possible to provide curved force receiving surfaces such as a rounded corner on each engaging portion 505, 506.The front end portion of the lock member 501 is configured such that the engaging portions 505, 506 can be engaged with a retaining portion of the child seat 3. In the rear portion of the lock member 501, two guide slots 528 are provided. The slots 528 extend parallel to one another and in the main direction of extension of the locking component 501.A support portion 529 for supporting an urging member such as a spring is provided between the slits 528. The support portion 529 is configured like a finger and is provided in a projected manner in a central portion of the lock member 501 and extends in an opposite direction with respect to the direction in which the engaging portions 505, 506 extend.As shown in FIG. 12, an urging member 503 may be slidably supported on the support portion 529 such that one end abuts against a body of the locking member 501 and the other end is free to be supported on a stationary portion of the base 2. The urging member 503 may be configured to apply an urging force to the locking member 501 so as to be biased toward the standby position.Further, as shown in FIG. 30, a magnet holder 524 is provided at a rear portion of the locking member 501. The magnet holder 524 protrudes from an upper surface of the locking member 501 and holds a magnet 526. The magnet serves as a sensor detectable feature for determining the position of the locking member 501 in the locking mechanism 500. In the configuration shown, the magnet 826 is held on the locking member 501 to be movable integrally with the locking member 501. As further illustrated in FIG. 31, two sensors 808, 810 may be provided in the locking mechanism 500. The sensors may be disposed on the locking member 501 in alignment with a moving direction of the magnet 526. The locking member 501 is translationally movably provided in the locking mechanism 500. Accordingly, when the locking member 501 is moved, the magnet 526 is moved in a straight path.The sensors 808, 810 are arranged on a straight line parallel to the straight path on which the magnet 526 moves during movement of the locking member 501. The two sensors 808, 810 are offset with respect to each other and spaced apart with respect to each other. The two sensors 808, 810 are configured to sense the magnet when moved together with a locking member 501 between the standby position, the locking position and the release position. The sensor assembly 800 is configured to sense a triggering sequence of the sensors 808, 810 by the magnet 526. A positive lock signal may be output when a predetermined triggering sequence is detected. One of the two sensors 808, 810 forms a first anti-rotation sensor 808 and the other of the two sensors forms a second anti-rotation sensor 810.In the example configuration, the first rotation lock sensor 808 is provided before the second rotation lock sensor 810, and is disposed between the second rotation lock sensor 810 and a position of the magnet 526 when the lock member 501 is in the standby position. As shown in FIG. 31, the magnet 526 passes under the first rotation lock sensor 808 when the lock member 501 is moved from the standby position I to the release position III. In the locking position II in which the engaging portions 505, 506 engage with a retaining portion of the child seat, the magnet 526 is vertically below the first rotation lock sensor 808. In the configuration shown, the first anti-rotation sensor 808 and the second anti-rotation sensor 810 are Hall sensors. Further, the sensors 808, 810 may be configured to enable make-before-break detection of the magnet 526. That is, the configuration may be such that the second rotation lock sensor 810 already detects the presence of the magnet 526, while the first rotation lock sensor 808 still detects the presence of the magnet 526. By using such a sensor arrangement, it is possible to reliably detect whether the locking member 501 correctly moves from the standby position I to the locking position II via the release position III. Accordingly, a positive locking signal of the locking mechanism 500 may be output in some configurations only when it is detected that the locking member 501 has moved from the standby position I, which may also be considered a fully extended position, to the release position III, which may be considered a fully retracted position of the locking member 501, and then to the locking position II. In this way, the locking member 501 must move completely to the retracted position and then to the locking position to output a positive locking signal. In this way, locking of the child seat can be detected more reliably.In another configuration, a positive lock signal of the lock mechanism can be output without detecting the above-mentioned release position III. In this configuration, it is sufficient to detect that the locking member 501 is in the locking position II and / or that the locking member 501 has been moved from the standby position I to the locking position II. In such a configuration, the second rotation lock sensor 810 may be omitted, although it is possible to additionally provide this sensor for additional detection accuracy and reliability.Example Basis with Detection of a Correctly Deployed Child Seat (Two-Sensor Detection)The sensor arrangement 800 may be configured to detect a correct support of the child seat 3 on the base 2 and to detect a correct orientation of the child seat 3 on the base 2. Further, the sensor arrangement 800 may be configured to output a confirmation signal when the correct support of the child seat 3 and the correct orientation of the child seat 3 are detected. The confirmation signal may include turning on a light source without changing the colors of the light source. The light source may be part of a display portion 1000.In an exemplary configuration, a base 2 for a child restraint system 1 may be provided that includes a primary support portion 101, a locking mechanism 500, a seat detection sensor 802, and a rotation lock sensor 808, 810. Further, the base 2 may include a processing unit configured to receive signals from the seat detection sensor 802 and the anti-rotation sensor 808, 810. The processing unit may be configured to output a signal indicating correct or incorrect mounting of the child seat 3 on the base 2 based on the signals received from the seat detection sensor 802 and the rotation lock sensor 808, 810. More specifically, when the seat detection sensor 802 detects a seat correctly seated and the rotation lock sensor 808, 810 detects a child seat correctly locked against rotation, the processing unit may output a signal indicating correct mounting of the child seat 3 on the base 2.Example Base Including Magnetic Sensor in Lower Portion For Detecting Position of Load LegIn some configurations, a load leg 900 for supporting the base 2 is provided on a vehicle floor portion. The load leg 900 may be rotatably mounted to the base 2 and movable between a storage position in which the load leg 900 is folded against the lower portion 6 and an extended position in which the load leg 900 is capable of supporting the base 2 on the vehicle floor portion. Figures 34-36 show various states of a load leg 900 provided on the base 2 in some configurations. In the illustrated configuration, the load leg 900 is rotatably coupled to the front portion 4 of the base 2 in a region where a locking mechanism 500 and a display portion 1000 are provided.The load leg 900 may include a coupling portion 902 rotatably coupled to a main body 20 of the base 2. The coupling portion 902 may also be referred to as the upper portion of the load leg. An opposite end portion of the load leg 900, which may also be referred to as a lower portion, may include a foot 904 configured to be contacted with the vehicle floor portion. As can be seen from Fig. 36, the load leg can be adjustable in length. More precisely, the load leg can be telescopic. Accordingly, the foot 904 may be disposed on the load leg to be movable between a retracted position as shown in FIGS. 34 and 35 and an extended position as shown in FIG. 36. The load leg 900 may include an outer profile 906 and an inner profile 908 movably housed within the outer profile 906. FIG. 34 shows a state in which the load leg 900 is in a storage position. FIG. 35 shows a state where the load leg is in an extended position with the foot 904 in a retracted position. FIG. 36 shows a state where the load leg is in the extended position and the foot 904 is in an extended position.A child restraint system 1 including such a load leg 900 may be configured to detect at least one of the storage position of the load leg 900 and the deployed position of the load leg 900 by a sensor. In some configurations, the infant restraint system 1 may include a base 2 having magnetic sensors for detecting the positions of the load leg. Accordingly, at least one of the storage position and the deployed position may be detectable by a sensor 812, 814, for example a magnetic sensor, provided on the base 2. The load leg extended position sensor 812 may also be referred to as a load leg extension state detection sensor. The load leg storage position sensor 814 may also be referred to as a load leg storage state detection sensor. Accordingly, in some configurations, the base 2 may include a magnetic sensor 812 provided on the lower portion 6 of the base 2, as illustrated in FIGS. 33 and 42, for example. The magnetic sensor 812 may be a proximity detection sensor.The load leg 900 may include a magnet 918 provided at a position that enables detection by the magnetic sensor 812 when the load leg 900 is in the storage position. For example, as shown in FIG. 39, the magnet 918 may be provided in a free end portion or foot 904 of the load leg 900. The magnet 918 is provided on a side of the load leg 900 that is oriented toward the lower portion 6 when the load leg 900 is in the storage position in this configuration. Accordingly, the magnet 918 is detectable by the magnetic sensor 812. In some configurations, the magnetic sensor 812 is covered by a magnetically attractable portion. FIG. 29 shows an exemplary configuration in which the magnetic sensor 812 is covered by a cover 29. More specifically, the cover 29 covers an opening 8 in the lower portion 6. The cover 29 may include, for example, a steel plate. The cover 29 is thus available as a magnetically attractable portion. The magnet 918 and the cover 29 are configured such that a magnetic attractive force therebetween is strong enough to maintain the load leg 900 in the storage position. Accordingly, in some configurations, the magnet 918 has a dual function by acting as a sensor detectable feature for the sensor 812 and acting as a member for generating a holding force to hold the load leg 900 in the stowed position.In some configurations, only one function of the dual function described above may be provided. For example, a magnet 918 may be provided in the load leg and a magnetic sensor 812 may be provided on the base. Only one position detection may be provided, and the holding function by magnetic attraction may be omitted. On the other hand, it is also possible to provide only the magnetic attraction function as described above and omit the magnetic sensor 812 in some configurations. Again, it is noted that one or more of the magnetic sensors described herein may be a Hall sensor.Example base having a load leg with a magnet in an upper leg portion,In some configurations, the infant restraint system 1 is configured to detect the deployed position of the load leg 900 using a contactless sensing arrangement. The contactless sensing arrangement may include a sensor 814, for example a magnetic sensor, for example a Hall sensor.As can be seen from Figs. 37 to 41, the load leg 900 may be coupled to the main body 20 of the base 2 by means of a pivot 912. Accordingly, the load leg 900 is rotatable about a pivot axis P 6 defined by the pivot pin 912 between the stowed position as shown in FIG. 37 and the deployed position as shown in FIG. 38. The coupling portion 902 of the load leg 900 is coupled to the main body 20 of the base 2 by the pivot 912. The load leg 900 may include a magnet 916 supported in the coupling portion 902 to be integrally rotatable with the load leg 900. Thus, as the load leg 900 rotates from the stowed position to the deployed position, the magnet 916 is correspondingly rotated about the pivot 912. The magnetic sensor 814 and the magnet 916 are arranged such that the magnet 916 passes the magnetic sensor 814 when the load leg 900 is rotated to the extended position. The distance between the pivot pin 912 and the magnetic sensor 814 is greater than the distance between the pivot pin 912 and the magnet 916. As the load leg 900 rotates to the extended position, the magnet 916 is moved into a region between the pivot 912 and the magnetic sensor 814. As illustrated in FIG. 40, the magnet 916 may be held by a magnet holder 914 in a central portion of the coupling portion 902 of the load leg 900. FIG. 41 is an enlarged view showing the position of the magnet 916 relative to the magnetic sensor 814 at a position where the magnet 916 has already passed the magnetic sensor 814 at a lower side of the magnetic sensor 814.Example Base with Sensors in ConnectorsIn some configurations, the base and / or the child restraint system 1 may include sensors 804, 806 for sensing a latch status of connectors 204, 206, such as coupling arms. Each connector may be configured to be releasably lockable to the vehicle seat with the attachment structure 96 of the vehicle. For example, the base may include a first connector 204 having a first sensor 804 and a second connector 206 having a second sensor 806. Each sensor 804, 806 may be configured and arranged to monitor a locking status of the connectors 204, 206 to the attachment structure 96 on the vehicle seat 90. More specifically, each sensor 804, 806 is configured to output a signal that reflects a locked state or an unlocked state of the respective connector 204, 206. Accordingly, the use of the signals from the sensors 804, 806 enables at least four different states of the sensors 804, 806 to be determined when considered in combination. Thus, a sensor arrangement 800 may be provided in which the locking status of each connector is independently detectable. A configuration in which the sensors 804, 806 are provided on a base 2 is shown in FIG. 29, for example. The sensors 804, 806 may be magnetic sensors. A possible internal configuration of connectors 204, 206 having magnet 246 as a sensor detectable feature for sensors 804, 806 is shown in Figure 48. The exemplary configuration of FIG. 48 is described in other parts of this specification.Example Base with Display Showing Spatial InformationIn some configurations, a child restraint system 1 may include a display portion 1000. For example, the display portion 1000 may be provided on a base 2. As shown in FIG. 1, the display portion 1000 may be provided in a front portion 4 of the base 2. Further, the display portion 1000 may be provided so as to be visible when the base 2 is viewed from above. The display portion 1000 may be provided at a position not covered by the child seat 3 when the child seat is inserted on the base 2 and oriented in a forward direction or a rearward direction. For example, the display portion 1000 may be provided above a locking mechanism 500 as described above. The display portion 1000 may be provided in an area where a load leg 900 is rotatably coupled to a main body 20 of the base 2. The display portion 1000 may be provided at substantially equal intervals from lateral sides of the base 2. In other words, the display portion 1000 may be provided centrally. Accordingly, the display portion 1000 may be visible to a user from both lateral sides of the base 2.The display portion 1000 may be configured to provide centralized information about the status of the child restraint system 1. For example, the display portion 1000 may be configured to provide information on the mounting status of the child restraint system 1.The display portion 1000 may be configured to display the information in a spatial manner that allows a user to directly spatially determine locations of portions on the infant restraint system 1 to which the displayed information relates.The display portion 1000 may be configured to display the information on a map 1002. Figures 43 and 44 show possible configurations of a card 1002. The card 1002 may show the child restraint system 1 or components of the child restraint system such as a base 2 or a child seat 3. In the example configurations as shown in FIGS. 43 and 44, the card 1002 shows the entire base 2 in a plan view. A top view illustration 1004 may be provided, schematically showing the base 2. The display portion 1000 may include a map 1002 in the form of a representation provided on the display portion 1000.The display portion 1000 may include at least one indicator 1012, 1014, 1016, 1018, 1020, 1022, 1024. The at least one indicator may be provided at a predetermined position on a map 1002. The predetermined position on the map 1002 may directly correspond to a location on the base 2.In some configurations, the display portion 1000 may include two indicators 1014, 1016, each indicating a coupling status of a connector 204, 206 or a coupling arm of the base 2. Such indicators may also be referred to as coupling indicators. For this purpose, the card 1002 may have a schematic illustration of the connectors 204, 206 in a schematic illustration of the base 2. The indicators are each provided adjacent to and / or associated with schematic representations of the connectors 204, 206 within the overall representation of the base 2. Accordingly, a first indicator 1014 may be provided adjacent to the illustration of the first connector 204 and a second indicator 1016 may be provided adjacent to the illustration of a second connector 206.The first indicator 1014 may be configured to indicate whether the first connector 204 is in a lock state or an unlock state. For example, when the first connector 204 is in the lock state, the first indicator 1014 may be active, e.g., lit, e.g., lit with green color. Similarly, the second indicator 1016 may be configured to indicate whether a second connector 206 is in a lock state or an unlock state. For example, when the second connector 206 is in the lock state, the second indicator 1016 may be active, e.g., lit. Accordingly, a user can easily grasp from the display portion 1000 whether a first connector 204 and a second connector 206 are locked to a mounting structure 96 of the vehicle seat 90. Further, when one of the connectors is not in the locking state and thus is not correctly locked to the mounting structure, a user can directly see on the display which one of the connectors is not in the locking state and where this connector is on the base 2.It is noted that both the first connector 204 and the second connector 206 may include a coupling portion 202 that is releasably lockable to the mounting structure 96 of the vehicle seat 90. Accordingly, the first indicator 1014 and the second indicator 1016 may be configured to indicate the respective state of the coupling portions 202 provided at the first connector 204 and the second connector 206. The respective state of the coupling portions 202 at the first connector 204 and the second connector 206 may be detected by sensors 804, 806, as described in other parts of this specification.In some configurations, the display portion 1000 may include at least one indicator 1018, 1020, 1024, each indicating a pairing status of a child seat 3 on a pairing interface 100 of the base 2, for example a pairing interface 100 having one or more of the features as described in other parts of this specification. Indicators 1018, 1020 may be associated with representations of a child seat 1006, 1008 (see FIG. 43 ) or a single indicator 1024 may be associated with the representation of a pairing interface on card 1002 in the base 2 representation (see FIG. 44 ). The indicators 1018, 1020, 1024 are configured to be turned on when a child seat is properly deployed on the coupling interface 100, for example, when the child seat 3 is properly deployed on a primary support portion 101 as described in other parts of this specification and / or when the child seat 3 is properly deployed in a secondary support portion 102, 103 as described in other parts of this specification. For example, a correct insertion of the child seat 3 on the base 2 may be indicated by the indicators 1018, 1020, 1024 when the child seat is correctly mounted on the primary support portion 101 and correctly oriented in a driving direction, for example, in a forward direction or a rearward direction.In some configurations, the display portion 1000 may include at least one indicator 1012 that indicates an extended position and / or a correct mounting state of a load leg 900 on the base 2. The extended position may be a state in which an extended position of the load leg 900 is detected, for example by a sensor arrangement, in particular a contactless detection arrangement. For example, the sensor assembly may include a sensor 814 as described in other parts of this specification.The display portion 1000 may further include an indicator 1022, adjacent to a representation of a battery icon 1010, for indicating a power supply status to a user.The load leg indicator 1012 may be provided at a front end portion of the card 1002. The coupling indicators 1014, 1016 may be provided at a rear end portion of the card 1002. The seat indicators 1018, 1020, 1024 may be provided in a middle portion between the load leg indicator 1012 and the coupling indicators 1014, 1016.In some configurations, another indicator 1058 may be associated with a representation indicative of a pressure applied by the base 2 to a vehicle seat 90, for example, a pressure pressing an anti-rebound portion 300 against a seat back 92 of a vehicle seat 90. Such an indicator 1058 may also be referred to as a pressure indicator. A pressure sensor may be provided in the bottom of the base 2 and / or in a surface of an anti-rebound portion facing the backrest. The pressure indicator may be illuminated (e.g., in green color) when a sufficiently high pressure is detected by the pressure sensor.Example Base with Alternative DisplayIn some embodiments, a display portion 1050 may differ from the display portion 1000 in that it shows at least one indicator row array, for example a column 1054, 1056 having multiple indicators, and a representation row array, for example a column 1052 showing representations of specific portions and configurations of the base 2. An indicator of the indicator row array, for example column 1054, 1056, may be associated with a representation in the parallel representation row array, for example representation column 1052, by being located at the same level and adjacent to the representation. The representations may be arranged according to an assembly sequence of the base 2 and / or a child seat 3 mounted thereon, i.e. an assembly sequence of a child restraint system 1. It should be noted, however, that the system provided herein does not require a user to perform the assembly steps in such a sequence. In some embodiments, two rows of indicators 1054, 1056 are provided, one on each lateral side of the display column 1052, such that two indicators are associated with a single display.The idea behind such an arrangement can be seen at least in a configuration in which a completely correct installation of the base 2 and / or the child seat 3 is represented by a row / column / row of indicators, so that it is easily recognizable to a user when there is a problem in one of the assembly steps, since it is easily recognizable when one of the indicators does not show a correct execution of the associated assembly step.FIG. 45 shows an exemplary configuration of a display device 1050 in which indicators and representations are arranged in parallel columns extending in the longitudinal direction of the base 2. In this configuration, two rows of indicators 1054, 1056 are provided, one on each lateral side of the display column 1052, such that two indicators are associated with each display in the display column 1052. Both indicators reflect the same information and they are both lit simultaneously.Example Display with Beam SplitterIn some embodiments, the child restraint system 1 may include a display portion 1000 configured to provide centralized information about the status of the child restraint system, and the display portion 1000 may include at least two indicators 1018, 1020 indicating a predetermined status of the child restraint system. The centralized information may include, for example, information about the mounting status of the child restraint system. In some embodiments, the child restraint system 1 may include a display portion 1050 as described above. Further, the display portion may include features as described herein in connection with other possible configurations of display portions.In some embodiments, at least two of the indicators 1018, 1020 of the display device 1000 or indicators of two indicator columns 1054, 1056 of the display device 1050 may be configured to be simultaneously illuminable by a single light source. In some embodiments, the display device 1000, 1050 may include a beam splitter 1001 (see, for example, FIG. 13 showing an example of an internal configuration of the display device 1000) for splitting and guiding emitted light from the single light source to the lighting portions 1018, 1020 or indicators, for example, the display device 1000, or to two lighting portions in a row of the two indicator columns 1054, 1056. The beam splitter 1001 may be formed integrally.Example Electronic Feedback SystemIn some configurations, an electronic feedback system may be provided. The electronic feedback system may include a microcontroller unit (MCU) 1060. The MCU 1060 may be coupled to one or more sensors of the sensor assembly 800 described herein through suitable wiring. The MCU 1060 may be configured to receive one or more signals from the one or more sensors of the sensor assembly 800, and may output signals reflecting predetermined conditions in an assembly process of the child restraint system to a display device 1000, 1050. The purpose of the electronic feedback system may be to indicate a status of various inputs (e.g., from the one or more sensors in the sensor assembly 800) and / or a battery level. The status can be displayed visually and / or audibly. For example, LEDs may be used for visual display. One or more of the LEDs may be bi-colored (e.g., red and green). A buzzer or loudspeaker may be provided for acoustic display.The MCU 1060 may be integrated into the display portion 1000 as shown in FIG. 37. The MCU 1060 may be provided in another place and may be suitably wired to the display portion 1000. The MCU 1060 may be further connected to a speaker to output audio information through appropriate wiring. A power supply portion 28 may be provided on the base 2 as shown in FIG. 29. The power supply portion 28 may be a battery case accessible through a lid provided on the lower portion 6 of the base 2, for example, in a lower surface 24 of the base 2. the power supply portion 28 is connected to the MCU 1060 through an appropriate wiring.The MCU 1060 may be configured to provide a standby mode in which the display portion 1000 is deactivated or turned off. Such a standby mode can also be referred to as a power saving mode. The MCU 1060 may be further configured to provide an active mode in which information is displayed on the display portion 1000. The MCU 1060 may be configured to provide a system test mode. The system check mode may be established during the active mode and / or the standby mode. In some configurations, the system check mode may be established upon actuation of the system check button by a user.The MCU 1060 may be configured to establish the standby mode when it is detected by the sensor 814 or the load leg storage state detection sensor that the load leg 900 is in a storage position. The MCU 1060 may be configured to establish the standby mode when no state change is detected by one or more of the sensors within a predetermined time period from waking up the system or a previous state change detected by a sensor, for example, within two minutes.The MCU 1060 may be configured to establish the active mode or wake the system from the standby mode when a change in state is detected by one or more of the sensors. In some configurations, any sensor change anywhere in the system wakes up the system. Such a change in state can be a change in the respective sensor from a detection of the sensor-detectable feature to a non-detection of the sensor-detectable feature or vice versa.For example, the MCU 1060 may be configured to establish the active mode or wake up the system from the standby mode when the load leg 900 is moved from the stowage position, resulting in a state change in the sensor 812 (load leg extension state detection sensor). The MCU 1060 may be configured to establish the active mode or wake up the system when the state of a coupling portion 202 changes from locked to unlocked and / or vice versa. The MCU 1060 may be configured to establish the active mode or wake up the system when a child seat 3 is inserted into or removed from the coupling interface 100. The MCU 1060 may be configured to establish the active mode or wake up the system when a child seat 3 is rotated to or from a forward-facing orientation or a rearward-facing orientation due to a change in state in one of the sensors 808, 810 in the locking mechanism 500.The MCU 1060 may also be configured to establish the active mode or wake up the system upon actuation of an actuation member by a user. The actuator may be provided as a separate component with the only function that allows a user to wake up the system. The actuation member may be a member operatively connected to a sensor detectable feature such that the sensor detectable feature is moved relative to the sensor with the effect that the MCU 1060 may restore the active mode based on detecting a change in state in the sensor associated with that sensor detectable feature. For example, the actuation member 119 or the release member 502 may form such an actuation member when coupled to the locking member 501 that carries a sensor detectable feature, for example the magnet 526. In such a configuration, a user can wake up the system by operating the operation member 119 or the release member 502. With respect to possible configurations of the operation member 119 or the release member 502 and the lock member 501, the other parts in this specification are referred to.The electronic feedback system may have a fail-safe configuration. For example, the electronic feedback system may be configured to detect sensor breaks and / or issues in signal transmission between the sensors and the MCU. As mentioned previously, the MCU may establish a system check mode. In the system test mode, the MCU 1060 may repeatedly test one or more of the sensors for proper operation, for example, every two seconds. For example, the sensors may be sensed for a fault in the signal link. As described in other portions of the specification, the sensors may be Hall sensors.As an example, the electronic feedback system may be configured such that the system wakes up and begins to emit sound when the load leg 900 is moved away from the stowage position. In addition, all indicators on the display devices 1000, 1050 except the battery indicator may blink. This may indicate that the load leg is neither in the stowed position nor in the deployed or deployed position.The electronic feedback system may be configured to transition to the standby mode or sleep mode when all indicators relating to states of the child restraint system signal a positive state, for example coupling portions locked, load leg extended, seat correctly installed and aligned and / or optionally sufficiently high pressure between base and seat. In this case, the system may be configured to enter standby mode after a predetermined period of time after all indicators show a positive state. The predetermined time period may be, for example, 30 s. If a condition is negative, the system may be configured to enter standby mode after a longer period of time, for example after two minutes.To sense the sensors for a fault in the sensor connection, the MCU may perform the following actions. If the signal is high, set low and wait until the capacitor discharges. If the signal is low, set high and wait until the capacitor charges. Read the input to see if the value has changed. When it has changed, the sensor operates normally. Three measured values can be taken from each sensor. A single deviation can be permitted per sensor signal, which enables a change of state of the sensor.The electronic feedback system may be configured such that no potentially annoying indications are made on the display portion 1000, 1050. For example, when no child seat 3 is mounted on the base 2, no indications regarding the mounting of the child seat 3 are provided on the display portion 1000, 1050. Thus, the focus can be placed on the mounting of the base. The system may be configured such that only indications regarding the base 2, for example the state of the coupling portions 202 (sensors 804) and / or the state of the base regarding the contact pressure on the seat (pressure sensor), are provided until the base 2 is correctly mounted on the vehicle seat, and indications regarding the mounting of the seat on the base are provided only when the base 2 is already correctly mounted.The electronic feedback system may be configured such that the MCU may be in sleep or standby mode for a first predetermined period of time, for example 100 ms, and then awakened triggered by a real-time clock. The MCU may then check whether one of the inputs has changed. Every second predetermined time period, for example two seconds, the MCU may also check whether the sensors connected to the input are functioning correctly. In some configurations, there may be five indicators, for example two-color LEDs.An acoustic indicator may be a beep generated by a buzzer. The acoustic indicator may indicate a sensor fault, a low battery level, and / or a load leg is positioned neither in the stowed position nor the deployed position.Example Coupling Arrangement with Two Coupled ConnectorsAn example configuration of a coupling assembly 200 for coupling a child restraint system 1 or a base 2 to the mounting structure on the vehicle seat will be described with reference to FIGS. 46 to 49. It is noted that some embodiments of a possible coupling arrangement 200 have already been described in connection with the configuration shown in FIGS. 17 and 18.The exemplary configuration as shown in FIGS. 46 and 47 includes two connectors 204, 206. Each connector may have an elongated structure. Each connector 204, 206 may also be referred to as a coupling arm in some embodiments due to its elongated structure.The connectors 204, 206 may be connected to one another by means of a connecting device 208. The connector 208 may provide a rigid support between the connectors 204, 206. Accordingly, the connectors 204, 206 may be formed together with the connector 208 as an integral unit. Therefore, the connectors 204, 206 can then be moved only jointly and not individually.In some embodiments, each of the connectors may be configured to be prevented from moving to a retracted position, for example, to or into the main body 20 of the base 2, when the coupling portion 202 is not correctly coupled to the mounting structure 96. In some embodiments, each of the connectors may be configured to be prevented from moving to an extended position, for example, out of and / or away from the main body 20 of the base 2, for example, by locking portions 214. In any of the latter cases, an entire unit including the connectors 204, 206 and the connector 208 may be moved only when none of the connectors 204, 206 is prevented from moving. In other words, the mobility of a single connector depends not only on whether this single connector can move freely, but also on whether the other connector can move freely.Each connector 204, 206 may include a coupling portion 202, for example, the coupling portion 202, as described in other parts of this specification. The coupling portions 202 may be configured to releasably engage a mounting structure 96 on the vehicle seat 90. The coupling assembly 200 may include a driven portion 210 provided on the connector 208 midway between the connectors 204, 206 in the configuration shown. In other words, the driven portion 210 may be centrally connected to the connector 208.The driven portion 210 may be configured to receive an actuation force for moving the coupling assembly 200, for example, from an actuation member 402 of a tensioning mechanism 400 as described in this specification. To this end, the driven portion 210 may include a toothed rod 211 engageable with a gear or drive pinion, for example a drive pinion or gear 472 of a tensioning mechanism 400 as previously described with reference to FIGS. 17 and 18.In some embodiments, the driven portion 210, for example, the toothed rod 211, and / or the force output member 470, for example, at least the gear 472, may be at least partially accommodated in the accommodation space 115 of the primary support portion 101 described in other parts of this specification.The coupling assembly 200 may be configured to automatically move to an extended position. The coupling assembly 200 of FIGS. 46 and 47 may include an urging member 212 that biases the coupling assembly 200 toward an extended position. The deployed position may be a position in which the coupling portions 202 project further from the...

Claims

A base (2) for a child restraint system (1) comprising a primary support portion (101) protruding from an upper surface portion (118) of the base (2) in a first direction (D1), the primary support portion (101) being configured to be releasably engaged by an engagement portion (51, 52) of an inserted child seat (3) in a positive locking manner to block movement of the child seat (3) in the first direction (D1) and being configured to rotatably support the child seat (3) about a rotational axis (R1) extending parallel to the first direction (D1), wherein a lateral outer surface (104) of the primary support portion (101) comprises a circumferential recess (105) configured to receive the engagement portion (51) of the child seat (3) to establish the positive locking connection, thereby enabling to, coupling the child seat (3) to the primary support portion (101) at any number of angular orientations about the axis of rotation (R1).The base (2) according to claim 1, wherein the primary support portion (101) is configured to support the main weight of a mounted child seat (3), and / or wherein the primary support portion (101) is configured to support the child seat (3) at a predetermined distance from the upper surface portion (118), and / or wherein the primary support portion (101) is configured as a stationary support portion.Base (2) according to any of the preceding claims, wherein the primary support portion (101) comprises an upper portion (107) supported by a pillar portion (106) in an overhanging manner such that an overhanging portion (108) of the upper portion (107) is available for establishing the positive locking, wherein the circumferential recess (105) may be bounded by a lower surface (109) of the upper portion (107) and an outer surface (114) of the pillar portion (106), wherein the pillar portion (106) may be at least partially tapered towards the upper portion (107).The base (2) according to any one of the preceding claims, wherein the upper portion (107) comprises a layered structure comprising an upper layer (110) and a lower layer (111) supporting the upper layer (110), the upper layer (110) being configured to come into sliding contact with a lower supporting surface (34) of the child seat (3) to be supported.The base (2) according to claim 4, wherein the lower layer (111) has a higher stiffness than the upper layer (110), and / or wherein the upper layer (110) comprises a low friction material, in particular a synthetic material, for example polyoxymethylene, configured to come into sliding contact with the child seat (3), and / or wherein the lower layer (111) comprises a metal material, and / or wherein the upper layer (110) at least partially surrounds an outer edge region of the lower layer (111), wherein a bottom side of the lower layer (111) may be exposed or uncovered, such that the engagement member (51, 52) of a mounted child seat (3) may come into direct contact with the lower layer (111).The base (2) according to any one of claims 4 and 5, wherein the upper layer (110) comprises a sliding surface (112) extending around a recess (113), wherein the sliding surface (112) may have a ring shape, and / or wherein the primary support portion (101) may be configured as a hollow body closed at the top and defining an accommodation space (115) in its interior, wherein the accommodation space (115) is configured to accommodate a portion of a tensioning mechanism (400) and / or a sensor of a sensor arrangement.The base (2) according to any one of the preceding claims, further comprising at least one secondary support portion (102, 103) radially spaced from the primary support portion (101) and configured to receive a retaining portion (32, 33) of the child seat (3) by rotating the child seat (3) about the rotation axis (R1) after the child seat (3) has been inserted on the primary support portion (101), wherein the at least one secondary support portion (102, 103) is configured to limit tilting movement of the child seat (3) about a rotation axis (R2) extending perpendicular to the rotation axis (R1), wherein at least one secondary support portion (102, 103) may comprise an urging member (609), for example a leaf spring (610), wherein the urging member (609) is provided to limit tilting movement of the child seat (3) about a rotation axis (R2) extending perpendicular to the rotation axis (R1), 33) to apply an urging force in a second direction (D2) opposite to the first direction (D1) when the retaining portion (32, 33) is accommodated in the secondary support portion (102, 103).The base (2) according to claim 7, wherein an insertion geometry of at least one secondary support portion (103) is mechanically encoded to block the child seat (3) from being positioned in a predetermined orientation, in particular a forward orientation of the child seat (3), and / or wherein the secondary support portion (103) comprises an abutting portion (120) configured to limit rotation of the child seat (3) about the rotation axis (R1) towards a forward orientation, wherein the abutting portion (120) may be configured to contact a stop portion (35) provided on the child seat (3) and may comprise abutting surfaces (121, 122) configured to contact stop portion surfaces (36, 37), wherein the abutting surfaces (121, 122) may be configured, in particular may be inclined, urging the stop portion (35) in a second direction (D2) opposite to the first direction (D1) when the stop portion (35) is pressed against the abutting portion (120) upon rotation of the child seat (3).The base (2) according to claim 7, wherein at least one secondary support portion (102) is configured such that a rotation of the child seat (3) about the rotation axis (R1) is automatically blocked when a rearward orientation is achieved when rotating it about the primary support portion (101), and / or such that the child seat (3) is normally prevented from achieving the forward orientation and is rotatable to the forward orientation only when an actuation member (119) is actuated by a user, wherein the actuation member (119) may be a release member (502) of a locking mechanism (500) for blocking a rotation of the child seat (3) about the rotation axis (R1), wherein the locking mechanism (500) is operably configured by an actuation force exerted thereon by the child seat (3), wherein the actuation force may be generated by a rotational force, which is exerted on the child seat (3) into which actuating force, in particular a pressing force, is transferred, wherein the locking mechanism (500) can have a locking component (501) which is movable between a locking position in which it can engage with the retaining portion (32, 33) and a release position in which rotation of the child seat (3) about the axis of rotation (R1) is not blocked, wherein the locking component (501) can be prestressed by an urging component (503) in such a way that movement of the locking component (501) in the direction of the release position is possible counter to an urging force exerted by the urging component (503), and wherein the locking component (501) can have a force-absorbing surface (504) which extends in such a way that the actuating force can be generated, by a force application surface (42, 43) on the child seat (3) and the force receiving surface (504) slidingly contacting when the child seat (3) is rotated about the rotation axis (R1).The base (2) according to any one of claims 7 to 9, wherein the secondary support portion (102, 103) comprises a support structure (600) for blocking lifting of the inserted retaining portion (32, 33) from the base (2) to prevent rotational movement of the child seat (3) in the event of an accident, wherein the support structure (600) may comprise a holder (601), wherein the holder (601, 602) may comprise a catch portion (603, 604), for example having a hook shape and configured to receive the retaining portion (32, 33), and wherein the holder (601, 602) is force-transmittingly coupled to a coupling portion (202) configured to be engaged with a fastening structure (96) in the vehicle seat (90), wherein the coupling portion (202) is coupled to a coupling arrangement (200), For example, an isofix arm may be provided and / or may be adjustably supported on the base (2) at the coupling portion (202) to allow tensioning of the base (2) to the vehicle seat, wherein the bracket (601, 602) may be force transmittingly coupled to the coupling portion (202) by means of a force transmission path comprising rigid force transmission members (605, 606, 607), for example by means of metal force transmission members or only by metal force transmission members, and / or wherein the force transmission members comprise a coupling portion support frame (606, 607), for example an isofix arm support frame, in particular a U-shaped housing, at which the coupling portion (202) is supported, and a coupling member (605), for example a rod (608), for coupling the bracket (601, 602) to the coupling portion support frame (606, 607), wherein the holder (601, 602) may be coupled to the coupling portion support frame (606, 607) only by a single coupling member (605).A child seat (3) couplable to a base (2) according to any preceding claim, the child seat (3) comprising an interface portion (30) releasably engageable with the primary support portion (101), the interface (30) comprising a recess (31) configured to receive the primary support portion (101) in the first direction (D) and a support surface (34) configured to contact a longitudinal end portion of the primary support portion (101), and a locking mechanism (50) for releasably locking the child seat (3) to the primary locking portion (101), the locking mechanism (50) comprising an engagement portion (51, 52) arranged to be radially movable into and out of the recess (31) so as to be capable of being locked, with the continuous circumferential recess (105) of the primary support portion (101), and an operation member (53) for retracting the engagement portion (51, 52), wherein an opening end portion of the recess (31) may be defined by an inclined circumferential wall portion (44) in which an outer diameter of the recess (31) is reduced from an opening toward the support surface (34).The child seat (3) according to claim 11, wherein the operating member (53) is positioned on the child seat (3) so as to be accessible only when the child seat (3) is rotated to an unlocking orientation different from a forward or rearward orientation of the child seat (3), wherein the operating member (53) may be provided at a lower side of the child seat (3) and at a position so as to be covered by the base (2) when the child seat (3) is in a forward or rearward orientation and is exposed only in the unlocking orientation, wherein the operating member (53) may be provided at a foot end of the child seat (3).A child restraint system (1) comprising a base (2) according to any one of claims 1 to 10 and a child seat (3) according to any one of claims 11 and 12 releasably mountable to the base (2).A base (2) for a child restraint system (1) comprising a primary support portion (101) configured to support a child seat (3) rotatably about a rotation axis (R1), at least one secondary support portion (102, 103) radially spaced from the primary support portion (101) and configured to receive a retention portion (32, 33) of the child seat (3) by rotating the child seat (3) about the rotation axis (R1) after the child seat (3) is inserted on the primary support portion (101), and configured to block movement of an inserted retention portion (32, 33) in a first direction (D1), wherein the at least one secondary support portion (102, 103) is configured to limit tilting movement of the child seat (3) about a rotation axis (R2) extending perpendicular to the rotation axis (R1).The base (2) according to claim 14, wherein at least one secondary support portion (102, 103) comprises an urging member (609), for example a leaf spring (610), the urging member (609) being provided to exert on the retaining portion (32, 33) an urging force in a second direction (D2) opposite to the first direction (D1), for example a downward direction, for example towards a base main body (20) and / or towards an upper surface (118) of the base (2) when the retaining portion (32, 33) is accommodated in the secondary support portion (102, 103).The base (2) according to any one of claims 14 and 15, wherein an insertion geometry of at least one secondary support portion (103) is mechanically encoded to block the child seat (3) from being positioned in a predetermined orientation, in particular a forward orientation of the child seat (3), and / or wherein the secondary support portion (103) comprises an abutting portion (120) configured to limit rotation of the child seat (3) about the rotation axis (R1) towards a forward orientation, wherein the abutting portion (120) is optionally configured to contact a stop portion (35) provided on the child seat (3) and optionally comprises abutting surfaces (121, 122) configured to contact stop portion surfaces (36, 37), wherein the abutting surfaces (121, 122) may be configured, in particular may be inclined, urging the stop portion (35) in a second direction (D2) opposite to the first direction (D1) when the stop portion (35) is pressed against the abutting portion (120) upon rotation of the child seat (3).The base (2) according to any one of claims 14 to 16, wherein at least one secondary support portion (102) is configured such that a rotation of the child seat (3) about the rotation axis (R1) is automatically blocked when a rearward orientation is achieved when rotating it about the primary support portion (101), and / or such that the child seat (3) is normally prevented from achieving the forward orientation and is rotatable to the forward orientation only when an actuation member (119) is actuated by a user, wherein the actuation member (119) may be a release member (502) of a locking mechanism (500) for blocking a rotation of the child seat (3) about the rotation axis (R1), wherein the locking mechanism (500) is operably configured by an actuation force applied thereto by the child seat (3), wherein the actuation force may be generated by a rotational force, which is exerted on the child seat (3) into which actuating force, in particular a pressing force, is transferred, wherein the locking mechanism (500) can have a locking component (501) which is movable between a locking position in which it can engage with the retaining portion (32, 33) and a release position in which rotation of the child seat (3) about the axis of rotation (R1) is not blocked, wherein the locking component (501) can be prestressed by an urging component (503) in such a way that movement of the locking component (501) in the direction of the release position is possible counter to an urging force exerted by the urging component (503), and wherein the locking component (501) can have a force-absorbing surface (504) which extends in such a way that the actuating force can be generated, by a force application surface (42, 43) on the child seat (3) and the force receiving surface (504) slidingly contacting when the child seat (3) is rotated about the rotation axis (R1).The base (2) according to any one of claims 14 to 17, wherein the secondary support portion (102, 103) comprises a support structure (600) for blocking lifting of the inserted retaining portion (32, 33) from the base (2) to prevent rotational movement of the child seat (3) in the event of an accident, wherein the support structure (600) may comprise a holder (601), wherein the holder (601, 602) may comprise a catch portion (603, 604), for example having a hook shape and configured to receive the retaining portion (32, 33), and wherein the holder (601, 602) is force-transmittingly coupled to a coupling portion (202) configured to be engaged with a fastening structure (96) in the vehicle seat (90), wherein the coupling portion (202) is coupled to a coupling arrangement (200), For example, a connector (204, 206) such as an isofix arm may be provided and / or may be adjustably supported on the base (2) at the coupling portion (202) to allow tensioning of the base (2) at the vehicle seat, wherein the holder (601, 602) may be force transmittingly coupled to the coupling portion (202) by means of a force transmission path comprising rigid force transmission members (605, 606, 607), for example by means of metal force transmission members or only by metal force transmission members, and / or wherein the force transmission members comprise a coupling portion support frame (606, 607), for example a connector support frame or an isofix arm support frame, in particular a U-shaped housing on which the coupling portion (202) is supported, and a coupling member (605), For example, a rod (608) for coupling the holder (601, 602) to the coupling portion support frame (606, 607), wherein the holder (601, 602) may be coupled to the coupling portion support frame (606, 607) only by a single coupling member (605).The base according to any one of claims 14 to 18, wherein at least one of the at least one secondary support portion (102, 103) has a cantilever-formed construction in which a free end portion faces the primary support portion (101) and / or wherein at least one secondary support portion (102, 103) is configured to receive and / or engage the retaining portion (32, 33) of the child seat (3) at a bottom of the at least one secondary support portion (102, 103), and / or wherein the at least one secondary support portion (102, 103) comprises a finger pinch prevention arrangement that prevents a user from pinching a finger between the secondary support portion (102, 103) and a retaining portion (32, 33) when the retaining portion (32, 33) is engaged with the secondary support portion (102, 103), wherein the finger pinch prevention arrangement comprises an elastically deformable member, For example, a cover that protrudes laterally from the secondary support portion (102, 103) in a manner that the retaining portion (32, 33) first needs to pass the elastically deformable member when moving into the secondary support portion (102, 103), wherein the finger pinch prevention assembly may include a cover that covers a free end portion of the secondary support portion (102, 103) such that each rigid member is positioned further inside the cover in the moving direction of the retaining portion.A child seat (3) couplable to a base (2), the child seat (3) comprising an interface portion (30) releasably engageable with a primary support portion (101), the interface (30) comprising a recess (31) configured to receive the primary support portion (101) in a first direction (D1) and a support surface (34) configured to contact a longitudinal end portion of the primary support portion (101), and a locking mechanism (50) for releasably locking the child seat (3) to the primary locking portion (101), the locking mechanism (50) comprising an engagement portion (51, 52) radially movably disposed into and out of the recess (31) to be capable of engaging with the primary support portion (101), For example, with a continuous circumferential recess (105) of the primary support portion (101), and an operating member (53) for retracting the engagement portion (51, 52).The child seat (3) according to claim 20, wherein an opening end portion of the recess (31) is defined by an inclined circumferential wall portion (44) in which an outer diameter of the recess (31) is reduced from an opening toward the support surface (34).The child seat (3) according to any one of claims 20 and 21, wherein the operating member (53) is positioned on the child seat (3) so as to be accessible only when the child seat (3) is rotated to an unlocking orientation different from a forward or rearward orientation of the child seat (3).The child seat (3) according to claim 22, wherein the operating member (53) is provided at a lower side of the child seat (3) and at a position to be covered by the base (2) when the child seat (3) is in a forward or rearward direction and is exposed only in the unlocking direction, wherein the operating member (53) may be provided at a foot end of the child seat (3).A base for a child restraint system (1), wherein the base (2) is configured to be coupled to a vehicle seat (90), and comprises a tensioning mechanism (400) configured to generate a biasing force to urge the base (2) onto the vehicle seat (90) once the base (2) is operatively connected to a mounting structure (96) of the vehicle, wherein the tensioning mechanism (400) is configured such that a user can generate the biasing force by repeatedly reciprocating an actuating member (402) of the tensioning mechanism (400).The base (2) of claim 24, further comprising a coupling portion (202) for fixedly coupling the base (2) to a mounting structure (96) of the vehicle, an anti-rebound portion (300) configured to be contacted with a backrest (92) of the vehicle seat (90) to limit at least rotational movement of the base (2) toward the backrest (92) in a crash situation, wherein the tensioning mechanism (400) is configured to decrease a distance between the anti-rebound portion (300) and the coupling portion (202) to generate the urging force for urging the base (2) toward the vehicle seat (90), wherein the tensioning mechanism (400) is configured to:, a user can reduce the distance by repeatedly reciprocating the operating member ( 402).A base for a child restraint system (1), wherein the base may be a base according to any of claims 24 and 25, wherein the base (2) is configured to be coupled to a vehicle seat (90), and comprises a tensioning mechanism (400) configured to generate an urging force for urging the base (2) toward the vehicle seat (90) once the base (2) is operatively connected to a mounting structure (96) of the vehicle, wherein the tensioning mechanism (400) comprises an actuation member (402) and a display device (450) configured to display to a user when the actuation member (402) is ready for use for tensioning.The base (2) according to claim 26, wherein the base (2) comprises a coupling portion (202) for fixedly coupling the base (2) to a mounting structure (96) of the vehicle, an anti-rebound portion (300) configured to be brought into contact with a backrest (92) of the vehicle seat (90) to limit at least a rotational movement of the base (2) towards the backrest (92) in a crash situation, wherein the tensioning mechanism (400) is configured to decrease a distance between the anti-rebound portion (300) and the coupling portion (202) to generate the urging force for urging the base (2) onto the vehicle seat (90), wherein the tensioning mechanism (400) comprises the operating member (402) and a display device (450), which is configured to display to a user when the actuator (402) is ready for use for tensioning.The base (2) of any of claims 26 and 27, wherein the display device (450) is configured to provide a user with a visual and / or audible indication.The base (2) according to any one of claims 26 to 28, wherein the display device (450) is configured to move the operating member (402) to a predetermined display position, wherein to operate the tensioning mechanism (400) the operating member (402) may be movable between a stowage position, for example a position in which the operating member (402) is accommodated in the base (2) so as not to protrude beyond an upper surface portion (118) of the base (2), and an extended position, wherein the predetermined display position is an intermediate position between the stowage position and the extended position, wherein the base (2) may have a recess (22) in the upper surface portion (118) which allows to grasp the operating member (402), for example even in the stowage position, and / or wherein the display device (450) is configured to:, the operating member (402) to automatically move to the predetermined display position when the coupling portion (202) is engaged with the mounting structure (96) and / or when a distance between the coupling portion (202) and the anti-rebound portion (300) is reduced to a predetermined intermediate distance, for example, by pressing the base (2) toward the seat back (92) in a pressing direction (P 1) with the coupling portion (202) engaged.The base (2) according to claim 29, wherein the display device (450) may comprise two cooperating portions (452, 454), for example a toothed portion (452) and a recessed portion (454), wherein at least one of the two cooperating portions (452, 454) is movable relative to the other and the cooperating portions (452, 454) are configured to engage in a releasable manner when the predetermined display position is reached, wherein the two cooperating portions (452, 454) may be configured to restrict at least one movement of the actuating member (402) out of and / or into the predetermined display position, wherein one cooperating portion (452) of the two cooperating portions (452, 454) is provided on the actuating member (402) and the other cooperating portion (454) of the two cooperating portions (452, 454) is provided on the actuating member (402), 454) is provided on a main body (4) of the base.The base (2) according to any one of the preceding claims 24 to 30, wherein the actuating member (402) is power-transmittingly coupled to the coupling portion (202) by means of a ratchet mechanism (410) that allows a torque applied to the actuating member (402) to be transmitted only in a clamping direction, wherein the ratchet mechanism (410) may include a locking member (412), for example a spring-loaded locking member, configured to releasably lock the actuating member (402) to an output member (422), for example an output shaft, of the ratchet mechanism (400) such that the actuating member (402) is integrally movable with the output member (422), wherein the output member (422) may include a gear (424) fixed to the output member (422) to be integrally rotatable with the output member (422).The base (2) according to any one of the preceding claims 24 to 31, wherein the actuating member (402) is a lever (404) rotatable about a rotation axis (P1), for example a curved lever (404) rotatably supported at both of its ends, for example a U-shaped lever, and / or extends, for example, about a primary support portion (101) and is supported on opposite sides of the primary support portion (101), wherein the rotation axis (P1) of the lever (404) may extend in the transverse direction (C) of the base (2).The base (2) according to any one of the preceding claims 24 to 32, wherein the tensioning mechanism (400) is configured to move the coupling portion (202) relative to the anti-rebound portion (300), for example to translate the coupling portion (202), for example in a longitudinal movement direction (L1).The base (2) according to any one of the preceding claims 24 to 33, wherein the tensioning mechanism (400) is configured to move the anti-rebound portion (300) relative to the coupling portion (202), wherein the tensioning mechanism (400) may be configured to move the anti-rebound portion (300) translationally and / or rotationally.The base (2) according to any one of the preceding claims 24 to 34, wherein the coupling portion (202) is part of a coupling arrangement (200), wherein the coupling arrangement (200) may comprise two connectors (204, 206), for example coupling arms, optionally supported by a support structure (600) and movable between an extended position and a retracted position, wherein the two connectors (204, 206) may be coupled to each other by means of a connection device (208), for example a rigid connection member, so that they are integrally or at least jointly movable, wherein the coupling arrangement (200) may be centrally driven and / or may comprise a driven portion (210) force-transmittingly coupled to the connection device (208), wherein the driven portion (210) may be force-transmittingly coupled to a force output member (470) of the clamping mechanism (400), wherein the driven portion (210) may include a toothed portion, for example a rack, and wherein the power output member (470) may include a gear (472) that engages the driven portion (210).The base (2) according to any one of the preceding claims 24 to 35, wherein the operating member (402) is power-transmittingly coupled to the coupling portion (202) by means of a torque limiting mechanism (490) configured to limit a transmittable torque to a predetermined maximum torque.A base (2) for a child restraint system (1), the base (2) being configured to be coupled to a vehicle seat (90), and comprising a coupling portion (202) for releasably coupling the base (2) to a mounting structure (96) of the vehicle, a release mechanism (700) configured to release the coupling portion (202) from the mounting structure (96) and / or configured to release a ratchet tensioning mechanism (400) for reducing a distance between an anti-rebound portion (300) and the coupling portion (202), and / or configured to release movement of the coupling portion (202) relative to the anti-rebound portion (300), wherein the release mechanism (700) comprises at least one actuation portion (702, 704), wherein the actuation portion (702, 704), 704) on the base (2) so as to be accessible only when a child seat (3) is removed from the base (2).The base (2) according to claim 37, wherein the operating portion (702, 704) is provided on an upper surface portion (118) of the base (2) at a position covered by an inserted child seat (3), and / or wherein the base (2) comprises a cover member movable between a covering position in which the cover member covers the operating portion and a exposing position in which the operating portion is accessible for operation, wherein the cover member is configured to be moved to the covering position when an infant seat is inserted on the base (2).A base (2) for a child restraint system (1), wherein the base (2) is configured to be coupled to a vehicle seat (90), and comprises a coupling portion (202) for releasably coupling the base (2) to a fastening structure (96) of the vehicle, a release mechanism (700) for releasing the coupling portion (202) from the fastening structure (96) and / or for releasing a ratchet clamping mechanism (400) for reducing a distance between an anti-rebound portion (300) and the coupling portion (202), and / or is configured to release a movement of the coupling portion (202) relative to the anti-rebound portion (300), wherein the release mechanism (700) comprises two actuation portions (702, 704), wherein the release mechanism (700) is configured such that, releasing the base (2) from the fastening structure (96) is possible only by actuating both actuating sections (702, 704), in particular by actuating both actuating sections (702, 704) simultaneously or successively.The base (2) according to any one of the preceding claims 37 to 39, wherein the release mechanism (700) is configured to release the coupling portion (202) and the clamping mechanism (400) simultaneously, and / or wherein the two actuation portions (702, 704) may be provided on opposite sides of a primary support portion (101), wherein each actuation portion (702, 704) may comprise a lever.The base (2) according to any one of the preceding claims 37 to 40, wherein the actuating member (702, 704) comprises a coupling portion (706) for force transmittingly coupling the actuating member (702, 704) to the coupling portion (202), wherein the coupling portion (706) may be coupled to an end portion of a force transmitting member, for example a Bowden cable, wherein the force transmitting member may be adjustable to allow adjustment of a force transmission from the actuating member (702, 704) to the coupling portion (202).The base (2) according to any one of the preceding claims 37 to 41, wherein the release mechanism (700) is configured such that upon actuation of the release mechanism (700), the tensioning mechanism (400) is deactivated by transferring the tensioning mechanism (400) to a free-wheeling state, and / or wherein the tensioning mechanism (400) may comprise an actuation member (402) that is force-transmittingly coupled to the coupling portion (202) by means of a ratchet mechanism (410) that allows a torque applied to the actuation member (402) to be transferred only in a tensioning direction, and wherein the release mechanism (700) is configured to deactivate the ratchet mechanism (410) by transferring the ratchet mechanism (410) to a free-wheeling state.The base (2) of claim 42, wherein the ratchet mechanism (410) may include a locking member (412), for example a spring loaded locking member, configured to releasably lock the actuating member (402) to an output member (422), for example an output shaft, of the ratchet mechanism (400) such that the output member (422) is integrally movable with the actuating member (402), wherein the output member (422) may include a gear (424) attached to the output member (422) to be integrally rotatable with the output member (422), and / or wherein the release mechanism (700) may include a force transfer mechanism (705) configured to move the actuating portion (702, 704), for example a rotational movement of the actuating portion (702, 704) in a rotational direction (D3), transferring a movement of the lock member (412) in a releasing direction (D5), thereby releasing a lock between the operating member (402) and the output member (422).The base (2) of claim 43, wherein the force transmission mechanism (705) may include a force transmission member (710) configured to receive an actuation force from a force application portion (708) of the actuation member (702, 704) and move toward the locking member (412) upon receiving the actuation force, wherein the force transmission member (710) may include a force application surface (712) for contacting a force receiving portion (419) of the locking member (412), wherein the force application surface (712) may be in the form of an outer surface of a truncated cone to enable interaction with the force receiving portion (419) at different angular orientations of the actuation member (402).The base (2) according to claim 44, wherein the force transmission member (710) may be a sleeve extending around a rotation axis (P1) of the operating member (402) and slidably provided on the output member (422), and / or wherein the force transmission member (710) has a force receiving surface (711) and the force applying portion (708) has a force applying surface (709) contacting the force receiving surface (711), wherein the operating portion (702, 704) is configured to be rotatable about the rotation axis (P1) in a rotation direction (D3), and the force receiving surface (711) and the force applying surface (709) are configured such that the force transmission member (710) is wedge-shaped, which is generated by sliding contact between the force application surface ( 709) and the force receiving surface ( 711) and is displaceable in a displacement direction (D 4) along the rotational axis (P 1).A base (2) comprising the features of claims 41 and 45, wherein each actuating portion (702, 704) comprises a lever, and the coupling portion (706) and the force applying portion (708) are integrally formed on the lever.The base (2) according to any one of the preceding claims 37 to 46, wherein the coupling portion (202) is configured to automatically move to an extended position when a movement of the coupling portion (202) relative to the anti-rebound portion (300) is released by the release mechanism (400), and / or wherein the coupling portion (202) is biased by means of an urging member (212), for example a helical spring, in a direction away from the anti-rebound portion (300), and / or wherein the coupling portion (202) may be part of a coupling arrangement (200), wherein the coupling arrangement comprises at least one connector (204, 206), for example a coupling arm (204, 206), supported on a support structure (600) and movable between an extended position and a retracted position, wherein the at least one connector (204, 206) and the holding structure (600) are configured to be releasably lockable in order to lock the coupling portion (202) at a plurality of different locking positions on the holding structure (600), wherein at least one connector (204, 206) can have a locking portion (214) and the holding structure (600) has receiving portions (612), for example recesses, and the locking portion (214) can be configured to be releasably engageable with the receiving portions (612), wherein the release mechanism (700) is configured to release a locking between the connector (204, 206) and the holding structure (600) in order to enable a movement of the coupling portion (202) relative to the anti-rebound portion (300), wherein the coupling arrangement (200) can have two connectors (204, 206), which are supported by the holding structure (600) and each have a coupling portion (202), wherein the two connectors (204, 206) can be coupled to one another by means of a connecting device (208), for example a rigid connecting component, such that they are integrally movable, wherein the urging component (212) is configured and arranged to exert an urging force on the connecting device (208).A child restraint system (1) comprising: a display portion (1000) configured to provide centralized information about the status, for example, information about the mounting status, of the child restraint system (1), wherein the display portion (1000) is configured to display the information in a spatial manner that allows a user to directly spatially determine locations of portions on the child restraint system (1) to which the displayed information relates.The child restraint system (1) according to claim 48, wherein the display portion (1000) is configured to display the information on a card (1002) showing the child restraint system (1), for example, on a card (1002) showing a base (2) of the child restraint system (1), for example, showing the entire base (2) in a plan view or an outline view (1004).The child restraint system (1) according to claim 49, wherein the display portion (1000) comprises the card (1002), for example in the form of a representation provided on the display portion (1000), and wherein the display portion (1000) comprises at least one indicator (1012, 1014, 1016, 1018, 1020, 1022) provided at a predetermined position on the card (1002), wherein the predetermined position on the card (1002) directly corresponds to a location on the base (2).The infant restraint system (1) of claim 49, comprising two indicators (1014, 1016) each indicating a coupling status of a connector (204, 206) of the base (2).The infant restraint system (1) of claim 51, comprising an indicator (1012) that indicates a status of a load leg (900) of the base (2).The child restraint system (1) according to claim 52, comprising at least one indicator (1018, 1020; 1024) indicating an insertion status of a child seat (3) on the base (2).A child restraint system (1) comprising: two connectors (204, 206) each configured to be detachably lockable to a mounting structure (96) of a vehicle; a display portion (1000) configured to provide information about the mounting status of the connectors (204, 206), wherein the display portion (1000) is configured to present at least four different locking states of the two connectors (204, 206).The child restraint system (1) according to claim 54, further comprising a first sensor (804) provided in the first connector (204) and a second sensor (806) provided in the second connector (206), each sensor (804, 806) being configured and arranged to monitor a locking status of the connectors (204, 206) with a mounting structure (96) on a vehicle seat (90), wherein the display portion (1000) is configured to display the at least four different states based on an output of the first sensor (804) and the second sensor (806).A child restraint system (1) comprising: a display portion (1000) configured to provide centralized information about the status of the child restraint system (1), for example, information about the mounting status of the child restraint system (1), wherein the display portion (1000) comprises at least two lighting portions (1018, 1020) indicating a predetermined status of the child restraint system (1), wherein at least two of the lighting portions (1018, 1020) are configured to be simultaneously illuminated by a single light source.The infant restraint system (1) according to claim 56, comprising a beam splitter (1001) for splitting and guiding emitted light from the light source to the illumination sections (1018, 1020).A base (2) for a child restraint system (1) comprising a primary support portion (101) protruding from an upper surface portion (118) of the base (2) in a first direction (D1), the primary support portion (101) being configured to be detachably engaged by an engagement portion (51, 52) of an inserted child seat (3) in a positive manner to block movement of the child seat (3) in the first direction (D1), and being configured to rotatably support the child seat (3) about a rotation axis (R1) extending parallel to the first direction (D1), a seat detection sensor (802) for detecting the presence of an inserted child seat (3) on the primary support portion (101).The base (2) according to claim 58, wherein the seat detection sensor (802) is provided in the primary support portion (101), for example, in an accommodation space (115) inside the primary support portion (101) or in an upper portion (107) of the primary support portion (101).The base (2) according to any of claims 58 and 59, wherein the sensor (802) is a magnetic sensor, for example a Hall sensor.A child seat (3) mountable to a base (2), at least one sensor detectable feature (46, 47), for example a magnet, wherein the sensor detectable feature (46, 47) may be provided, for example, at a lower portion of the child seat (3), for example a support portion defining a support surface (34) of the child seat (3), wherein the sensor detectable feature (46, 47) is configured to trigger a seat detection sensor (802) for detecting the presence of the child seat (3) on the base (2) when the child seat (3) is correctly mounted and / or aligned on the base (2).The child seat (3) according to claim 61, wherein two detectable features (46, 47), in particular magnets, are provided at the lower portion of the child seat (3), for example on opposite sides of a rotation center of the child seat (3), wherein the detectable features (46, 47) may be arranged at an equal distance from the rotation center of the child seat (3).A base (2) for a child restraint system (1) comprising a locking mechanism (500) for blocking rotation of an inserted child seat (3) about an axis of rotation (R1), the locking mechanism (500) comprising a locking member (501) movable between a locking position (II) in which it is positioned to engage a restraining portion (32, 33) of the child seat (3) and a release position (III) in which the locking member (501) is in a position in which it cannot engage a restraining portion (32, 33) of the child seat (3) so that rotation about the axis of rotation (R1) cannot be blocked by the locking member (501), and a sensor arrangement (800) configured to:, detecting at least the presence of the locking member (501) in the release position (III).The base (2) according to claim 63, wherein the sensor arrangement (800) is configured to additionally sense the presence of the locking member (501) in the locking position (II).The base (2) according to any one of the preceding claims 63 or 64, further comprising a sensor detectable feature (526) operatively connected to the locking member (501) so as to be movable in dependence on movement of the locking member (501), for example between a first position corresponding to a locking position of the locking member (501) and a second position corresponding to a release position of the locking member (501), wherein the sensor detectable feature (526) may be arranged on the locking member (501) so as to be integrally movable with the locking member (501), wherein the locking member (501) may comprise a holder (524) for holding the sensor detectable feature (526).The base (2) of claim 65, wherein the sensor assembly (800) comprises two sensors (808, 810) configured to sense a single sensor detectable feature (526), wherein the sensor assembly (800) is configured to sense a triggering sequence of the sensors (808, 810) by the single detectable feature (526), wherein a positive lock signal is output when a predetermined triggering sequence is sensed.The base (2) of claim 66, wherein the predetermined triggering sequence includes at least sensing of the sensor detectable feature (526) by a second sensor (810), for example while the sensor detectable feature (526) is still sensed by the first sensor (808), and / or vice versa.The base (2) according to any one of the preceding claims 63 to 67, wherein the sensor detectable feature (526) may comprise a magnet and wherein the sensors (808, 810) may be magnetic sensors, in particular Hall sensors.The base (2) of claim 68, wherein the sensors (808, 810) are arranged to enable make-before-break detection of the magnet (526).The base (2) according to any one of claims 63 to 69, wherein the locking member (501) is movable to a standby position (I) in which the locking member (501) is positioned in a fully extended position, wherein the sensors (808, 810) are positioned such that only one sensor (808) detects the sensor detectable feature (526) in the standby position, and wherein the locking position is a position between the fully extended position and the retracted position, wherein the fully extended position and the retracted position may be fixed end positions limiting a range of movement of the locking member (501).A base (2) for a child restraint system (1), wherein the base (2) is configured to releasably support a child seat (3), wherein the base (2) comprises a sensor arrangement (800) configured to detect a correct support of the child seat (3) on the base (2) and to detect a correct orientation of the child seat (3) on the base (2), and configured to output a confirmation signal when the correct support of the child seat (3) and the correct orientation of the child seat (3) are detected.The base (2) of claim 71, wherein the confirmation signal includes turning on a light source without changing colors of the light source.A base (2) for a child restraint system (1) comprising a primary support portion (101) configured to support a child seat (3) rotatably about a rotation axis (R1), a locking mechanism (500) for locking rotation of the child seat (3) about the rotation axis (R1), a seat detection sensor (802) configured to detect at least the presence of the child seat (3), optionally configured to detect the presence and a predetermined allowable orientation of the child seat (3) on the primary support portion (101), a rotation lock sensor (808, 810) configured to detect whether a rotation of the child seat (3) is locked, and a processing unit configured to receive signals from the seat detection sensor (802) and the rotation lock sensor (808, 810) and to output a signal, indicating correct or incorrect mounting of the child seat (3) on the base (2) based on the signals it has received from the seat detection sensor (802) and the rotation lock sensor (808, 810).A child restraint system (1) comprising a base (2) mountable on a seat (90) of a vehicle, the base (2) comprising a lower portion (6) configured to contact a seat bottom (94) of the seat (90); a load leg (900) for supporting the base (2) on a vehicle floor portion, the load leg (900) being rotatably mounted on the base (2) and being movable between a storage position in which the load leg (900) is folded against the lower portion and an extended position in which the load leg (900) is capable of supporting the base (2) on the vehicle floor portion, wherein at least one of the storage position and the extended position is detectable by a contactless detection arrangement provided on the base (2), for example by a magnetic sensor (812, 814) provided on the base (2).The infant restraint system (1) according to claim 74, wherein the magnetic sensor (812) is a proximity detection sensor.The infant restraint system (1) of claim 74, wherein the magnetic sensor (812, 814) is a Hall sensor.The child restraint system (1) according to any one of claims 74 to 76, wherein the magnetic sensor (812) is provided at the lower portion (6).The child restraint system (1) according to any one of the preceding claims 74 to 77, wherein the load leg (900) has a free end portion (904) configured to be brought into contact with a vehicle floor portion, wherein a magnet (918) is provided in the free end portion on a side of the load leg (900) that is oriented toward the lower portion (6) when the load leg (900) is in the storage position.The infant restraint system (1) of claim 78, wherein the magnetic sensor (812) is covered by a magnetically attractable portion, wherein in the storage position of the load leg, a magnetic attractive force between the magnet (918) and the magnetically attractable portion is strong enough to hold the load leg (900) in the storage position.A child restraint system (1) comprising a base (2) mountable on the seat of a vehicle, the base (2) comprising a lower portion (6) configured to contact a seat bottom (94) of the seat (90); a load leg (900) for supporting the base (2) on a vehicle floor portion, the load leg (900) rotatably mounted on the base (2) and movable between a stowed position and a deployed position in which the load leg is capable of supporting the base against the vehicle floor portion, wherein the child restraint system (1) is configured such that the load leg (900) is releasably lockable by magnetic attraction in the stowed position.The infant restraint system (1) according to claim 80, wherein the load leg (900) comprises a magnet (918), wherein the magnet (918) may be provided in a free end portion (904) of the load leg (900), and wherein the base (2) comprises a magnetically attractable member, for example a steel plate (29).The child restraint system (1) according to claim 80 or 81, further comprising a proximity magnetic sensor (812) covered by the steel plate (29), such that the magnet (918) has a dual function of generating an attractive force in cooperation with the steel plate (29) and is detectable by the magnetic sensor (812).A child restraint system comprising a base (2) mountable on a seat of a vehicle, the base (2) comprising a load leg (900) for supporting the base (2) on a vehicle floor portion, the load leg (900) being rotatably mounted on the base (2) at a coupling portion (902) and being movable between a stowage position and an extended position in which the load leg (900) is capable of supporting the base (2) against the vehicle floor portion, the child restraint system (1) being configured to detect the extended position of the load leg (900) by means of a contactless detection arrangement.Child restraint system (1) according to claim 83, wherein the contactless detection arrangement comprises a magnetic sensor (814), for example a Hall sensor.The infant restraint system (1) according to claim 84, wherein the load leg (900) includes a magnet (916) supported in the coupling portion (902) to be integrally rotatable with the load leg (900), and wherein the magnetic sensor (814) and the magnet (916) are arranged such that the magnet (916) passes the magnetic sensor (814) upon rotating the load leg (900) to the deployed position.A child seat (3), the child seat (3) comprising a seat structure (2100) comprising a lower portion (2102) and a backrest portion (2104), a belt assembly (2200) comprising a shoulder belt (2202) for restraining a seated child, a head restraint assembly (2300) for supporting the head of a seated child, the child seat (3) being configured such that a shoulder belt portion (2204) of the belt assembly (2200) is temporarily attachable to the head restraint assembly (2300) or to a lateral support portion of the seat structure, for example, to a front portion or an outer side portion of a shoulder support portion (2106,2112), wherein the shoulder support portion (2106,2112) may be provided to the backrest portion (2104).The child seat (3) according to claim 86, wherein the child seat (3) is configured such that the shoulder belt portion (2204) is attachable to the headrest assembly (2300) or the lateral support portion by magnetic attraction.The child seat (3) according to any one of claims 86 and 87, wherein the lateral support portion or the headrest arrangement (2300) comprises a support structure (2302) and a cover component (2304), for example a cover component made of fabric, wherein the support structure (2302) and / or the cover component (2304) comprises a magnet (2306), wherein the magnet (2306) can be provided at a front portion of the lateral support portion or at a front portion of the headrest arrangement (2300), for example at a lateral head support portion (2324, 2326) of the headrest arrangement (2300), in particular at an inner side of the headrest arrangement (2300), for example at or in inner support surfaces (2332, 2334), at an outer side of the front portion of the headrest arrangement (2300) or at the lower side of the front portion of the headrest arrangement (2300), wherein each lateral head support portion (2324, 2326), 2326) may include a magnet (2306) on an outer side, wherein the magnet (2306) may be arranged in a support structure (2302) of the headrest arrangement (2300) at a front end portion (2316) of the support structure (2302) provided in the lateral head support portions (2324, 2326), wherein the support structure (2302) may include a holding portion for accommodating the magnet, for example a recess (2318).The child seat (3) according to any one of claims 86 to 88, wherein the shoulder belt portion (2204) includes a magnetically attractable portion.The child seat (3) according to claim 89, wherein the shoulder belt portion (2204) includes a buckle member (2206) including the magnetically attractable portion.The child seat (3) according to claim 90, wherein the buckle component (2206) includes a buckle tongue (2208) forming the magnetically attractable portion.The child seat (3) of claim 91, wherein the buckle tongue (2208) is made of steel.A trim cover (2400) for a child seat (3), for example an infant seat, the trim cover (2400) comprising: a flexible trim portion (2408) configured to cover at least an outer portion (2140) of a seat structure (2100), the flexible trim portion (2408) comprising a trim edge portion (2410); and a mounting portion (2420) for coupling the trim edge portion (2410) to the seat structure (2100), the mounting portion (2420) being coupled to the cover edge portion (2410) and configured to come into surface contact with the flexible cover portion (2408) at a position within the cover edge portion (2410) when the mounting portion (2420) is coupled to the child seat (3).The trim cover (2400) of claim 93, wherein the attachment portion (2420) comprises a base portion (2422) comprising a trim cover portion support surface (2428) extending between a front portion (2430) and a rear portion (2432) of the base portion (2422), wherein the trim cover edge portion (2410) is fixedly coupled to the front portion (2430) at an attachment region (2412) of the trim cover edge portion (2410), in particular such that the flexible trim cover portion (2408) extends along the trim cover portion support surface (2428), wherein the trim cover portion support surface (2428) may form an outer surface of the base portion (2422).The trim cover (2400) of claim 94, wherein the attachment portion (2420) includes a support assembly configured to support the base portion (2422) on the seat structure (2100) in a predetermined orientation.The trim cover (2400) of claim 95, wherein the support assembly is configured to support the base portion (2422) on the seat structure (2100) such that the trim cover portion support surface (2428) at least partially increases an outer surface area (2142) of the outer portion (2140), the outer surface area (2142) facing laterally away from the seat structure (2100).The trim cover (2400) of claim 96, wherein the support assembly is configured to support the base portion (2422) on the seat structure (2100) such that the trim cover portion support surface (2428) extends at least partially beyond an edge portion (2144) that bounds the outer surface area (2142) of the outer portion (2140).The trim cover (2400) of claim 96 or 97, wherein the support assembly is configured to support the base portion (2422) to the seat structure (2100) such that the front portion (2430) including the attachment region (2412) of the trim cover edge portion (2410) is at least partially spaced from the edge portion (2144) delimiting the outer surface region (2142) of the outer portion (2140).The trim cover (2400) of any of claims 94 to 98, wherein the support assembly comprises a support protrusion (2424) protruding from the base portion (2422), wherein the support protrusion (2424) may protrude from an inner surface (2426) of the base portion (2422), wherein the inner surface (2426) and the trim portion support surface (2428) may be disposed on opposite sides of the attachment portion (2420), wherein the support protrusion (2424) may be formed as a continuous rib, wherein the support protrusion (2424) may comprise a support surface (2440) adapted to contact support protrusions (2116) on the seat structure (2100), wherein the support surface (2440) and the support protrusions (2116) may be configured to contact each other in surface, wherein the support surface (2440) may comprise a planar contact surface configured to contact each other, to contact a support surface (2118) on the support protrusions (2116).The trim cover (2400) according to any one of claims 94 to 99, wherein the front portion (2430) has an outer surface (2436) and an opposite inner surface (2438), wherein the trim cover edge portion (2410) may be arranged on the outer surface (2436), for example may be wound around the front portion (2430) to enclose the front portion (2430), in particular such that the edge of the trim cover portion (2408) is arranged on an inner side of the fastening portion (2420).The trim cover (2400) of any of claims 94 to 100, wherein the attachment portion (2420) is configured to hold the trim cover portion (2408) to the seat structure (2100) such that a substantially seamless transition from the trim cover portion (2408) to a back cover (2500) of the child seat (3) is provided, wherein the back cover (2500) may be dish-like and may form a hard dish portion.The trim cover (2400) of claim 101, wherein the front portion (2430) may be adapted to the shape of the back cover (2500), in particular to the shape of a back cover edge portion (2502) of the back cover (2500), such that upon mounting the attachment portion (2420) to the seat structure (2100), the front portion (2430) may be placed in a position within the back cover (2500) in which the front portion (2430) overlaps with the back cover (2500) such that the trim portion (2408) extends past the back cover edge portion (2502) into the back cover (2500).The trim cover (2400) of claim 102, wherein the front portion (2430) is provided on the base portion (2422) offset with respect to the trim cover support surface (2428), wherein a transition portion (2434), such as a step, may be provided between the front portion (2430) and the trim cover support surface (2428), wherein the transition portion (2434) may delimit the trim cover support surface (2428) and may be adapted to follow a contour of a back cover edge portion (2502), wherein the attachment portion (2420) is configured such that the trim cover portion (2408) is supported on the trim cover support surface (2428), wherein an outer surface of the trim cover portion (2408) is arranged flush with an outer surface of the back cover edge portion (2502), and / or such that, supporting the cover portion (2408) on the front portion (2430), wherein an outer surface of the cover portion (2408) is held between the front portion (2430) and the rear cover edge portion (2502), for example, is sandwiched between the front portion (2430) and the rear cover edge portion (2502).The trim cover (2400) of any one of claims 101 to 103, wherein the attachment portion (2420) is configured to only partially close a gap (2150) formed on the child seat (3) between the outer portion (2140) and the back cover (2500) while holding the trim cover portion (2408), such that an opening (2152) defined between the back cover (2500), the outer portion (2140), and an attachment portion (2420), particularly an upper portion (2444) of the attachment portion (2420) mounted on the seat (3) is covered by the trim portion (2408), the opening (2152) having a dimension that allows a user to pass a finger through the opening (2152) while deforming the trim portion (2408) covering the opening.The trim cover (2400) of any of claims 93 to 103, wherein the attachment portion (2420) is configured to be coupled to the child seat (3) with an insertion movement including a rotational push movement and / or may be configured to be decoupled from the child seat (3) by a decoupling movement including a rotational pull movement.The cover (2400) according to any one of claims 93 to 104, wherein the attachment portion (2420) is non-destructively detachable mountable to the child seat (3).The trim cover (2400) of any of claims 93 to 106, wherein the attachment portion (2420) has a higher stiffness than the flexible trim cover portion (2408).The trim cover (2400) of any of claims 93 to 107, wherein the trim cover edge portion (2410) is sewn and / or bonded and / or clipped to the attachment portion (2420).A child seat (3), the child seat (3) comprising a support structure (1100), a seat structure (1200) comprising a seat bottom (1202) and a seat back (1204), the seat structure (1200) being supported on the support structure (1100) and being configured to be transitionable between a seat configuration and a reclining configuration, the seat back (1204) being configured to be rotatable about a fixed rotational axis relative to the support structure (1100), for example about a first rotational connector (1208) rotatably coupling the seat back (1204) to the support structure (1100), the seat bottom (1202) being configured to be rotatable about a movable rotational axis, for example about a second rotational connector (1214) guided along a predetermined path, wherein the movable rotational axis is moved relative to the support structure (1100) during the transferring of the seat structure (1200) between the seat configuration and the reclining configuration, wherein the predetermined path is configured such that during the transferring of the seat structure (1200) between the seat configuration and the reclining configuration the movable rotational axis is moved at least temporarily in an upward direction relative to the support structure (1100).The child seat according to claim 109, wherein the predetermined path is a curved path, for example a circular path.The child seat (3) according to claim 109 or 110, wherein the second rotary connector (1214) is supported on the support structure (1100) by means of a lever (1216), wherein the lever can be coupled to the support structure (1100) by means of a third rotary connector (1212), wherein the third rotary connector (1212) can couple the lever (1216) to the support structure (1100) at a position below the second rotary connector (1214), or wherein the lever can be attached to the support structure (1100) in a pendulum-like manner, for example in such a manner that an end portion of the lever is attached to the support structure (1100) at a position above the second rotary connector (1214).Child seat (3) according to one of claims 109 to 111, wherein the axes of rotation extend parallel to one another.The child seat (3) of any of claims 109 to 112, wherein the seat bottom (1202) is hingedly coupled to the seat back (1204) by a fourth pivot connector (1210), the fourth pivot connector (1210) coupling the seat bottom (1202) and the seat back (1204) at a distance from a lower seating surface on the seat bottom (1202) and at a distance from a backrest surface of the seat back (1204), wherein the distance may be configured such that the fourth pivot connector (1210) is provided substantially at a natural hip joint level of a seated child.The child seat (3) according to any one of claims 109 to 113, wherein the second pivot connector (1214) is coupled to the seat bottom (1202) at a central portion of the seat bottom (1202), for example substantially halfway between a front end of the seat bottom (1202) and a rear end of the seat bottom (1202), wherein the seat bottom (1202) may be hingedly coupled to the seat back (1204) at a rear end portion thereof, and / or wherein an actuation portion (1222) is provided at a lower portion of the seat bottom (1202) and configured to receive a pulling force applied thereto by a user, wherein the actuation portion (1222) may be configured and arranged such that when the seat structure (1200) is in the seat configuration, a pulling force applied thereto acts in a pulling direction (D7) extending substantially perpendicular to the movable rotational axis and substantially tangential to the predetermined path.A connector (204, 206) for coupling a child restraint system to a vehicle seat, the connector (204, 206) comprising a coupling portion (202) provided at the first end portion and configured to be releasably locked to a mounting structure (96) of a vehicle seat, a locking portion (214, 216) spaced from the coupling portion (202) in a longitudinal direction of the connector, wherein the locking portion (214, 216) is movably disposed between a locking position in which the locking portion (214, 216) protrudes from an outer side of the connector (204, 206) and a release position in which the locking portion (214, 216) does not protrude from the lateral outer side, and wherein the locking portion (214, 216) is translationally movably disposed in a direction transverse to the longitudinal direction.The connector (204, 206) of claim 115, wherein the locking portion (214, 216) is linearly movable between the release position and the locking position.The connector (204, 206) of claim 116, wherein the locking portion (214, 216) is linearly movable in a direction perpendicular to the longitudinal direction of the connector.The connector (204, 206) of any of claims 115 to 117 comprising two of the locking portions, a first locking portion (214) and a second locking portion (216), wherein the first locking portion (214) has a stop surface oriented forwardly of the connector toward the coupling portion (202), and wherein the second locking portion (216) has a stop surface oriented rearwardly of the connector away from the coupling portion (202).The connector (204, 206) of claim 118, wherein the second locking portion (216) is operatively connected to the coupling portion (202) such that the second locking portion (216) is moved to the release position when the coupling portion (202) is engaged with the attachment structure (96).The connector (204, 206) of any of claims 118 and 119, further comprising a release portion (222) for manually moving the second locking portion (216) to the release position regardless of a coupling status of the coupling portion (202).The connector (204, 206) according to claim 120, wherein the releasing portion (222) is an operating portion of a force transmitting member (270), the force transmitting member (270) being linearly movable along the longitudinal direction of the connector (204, 206) between a releasing position and an operating position, and comprises a force applying portion (274) configured to cooperate with the second locking portion (216) such that the second locking portion (216) is moved toward the releasing position when the force transmitting member (270) is moved toward the operating position.The connector (204, 206) of claim 121, wherein the force transmitting member (270) is disposed between the coupling portion (202) and the second locking portion (216).The connector (204, 206) of any of claims 115 to 122, wherein each locking portion (214) is biased towards the locking position by an urging member, such as a spring.A coupling arrangement (200) for a child restraint system (1), the coupling arrangement (200) comprising two connectors (204, 206) according to any one of claims 115 to 123, and a connection device (208) rigidly coupling the two connectors (204, 206) to each other such that the two connectors (204, 206) are integrally movable.A base (2) for a child restraint system, the base (2) comprising a support structure (600), and a coupling assembly (200) according to claim 124, wherein the coupling assembly (200) is supported on the support structure (600) to be movable between an extended position and a retracted position, and is releasably lockable in at least one of the extended position and the retracted position by releasably locking the support structure (600) and the coupling assembly (200) by means of the locking portion (214, 216) in a positive manner.A child seat (3), the child seat (3) comprising a support structure (1100), a seat structure (1200) supported on the support structure (1100) and configured to be transferable between a seat configuration and a reclining configuration, an interface portion (30) for locking the child seat (3) to a base (2) fixedly mountable to a vehicle seat (90), the interface portion (30) being provided on the support structure (1100), wherein the child seat (3) is configured such that the transferableness between the seat configuration and the reclining configuration is suspended when the interface portion (30) is supported on the base (2) and the child seat (3) is oriented in a predetermined direction, for example, in a forward direction or a rearward direction.The child seat (3) according to claim 126, further comprising a locking mechanism (1220) for locking the seat structure (1200) in the seat configuration and / or the reclining configuration, wherein the locking mechanism (1220) comprises an operating member (1222) for temporarily unlocking the locking mechanism (1220), wherein the child seat (3) is configured such that unlocking of the locking mechanism (1220) is blocked when the interface portion (30) is supported on the base (2) and the child seat (3) is oriented in a predetermined direction, for example, in a forward direction or a rearward direction.The child seat (3) according to claim 127, wherein the operating member (1222) is provided on the child seat (3) so as not to be accessible to a user when the interface portion (30) is supported on the base (2) and the child seat (3) is oriented in a predetermined direction, for example, a forward direction or a rearward direction.The child seat (3) according to claim 128, wherein the interface portion (30) comprises a retaining portion (33) to be accommodated in a secondary support portion (102) of the base (2) when the child seat (3) is supported on the base (2) and oriented in the predetermined direction, wherein the operating member (1222) is provided on the child seat (3) adjacent to the retaining portion (33), for example at a predetermined position above the retaining portion (33), such that it is covered by a portion of the base (2), for example a portion of the secondary support portion (102), when the child seat (3) is supported on the base (2) and oriented in the predetermined direction.The child seat (3) according to any one of claims 127 to 129, further comprising a seat bottom (1202) and a seat back (1204), wherein the operation member (1222) is provided at a lower front end portion of the seat bottom (1202).A child restraint system (1) comprising a child seat (3) according to any one of claims 126 to 130, and a base (2) mountable to the vehicle seat (90) and configured to support the child seat (3), wherein the interface portion (30) is detachably couplable to the base (2), wherein the child seat (3) comprises a locking mechanism (1220) for locking the seat structure (1200) in the seat configuration and / or the reclining configuration, wherein the locking mechanism (1220) comprises an operating member (1222) for temporarily unlocking the locking mechanism (1220), wherein the child seat (3) and the base (2) are configured such that unlocking of the locking mechanism (1220) is blocked when the interface portion (30) is supported on the base (2) and the child seat (3) is oriented in a predetermined direction, For example, in a forward direction or a rearward direction.The child restraint system (1) according to claim 131, wherein the child seat (3) comprises at least one restraining portion (32, 33), wherein the base (2) comprises at least one secondary supporting portion (102, 103) configured to receive the restraining portion (32, 33) of the child seat (3), for example by rotating the child seat (3) about a rotation axis (R1), wherein the secondary supporting portion (102, 103) is configured such that the operating member (1222) on the child seat (3) is covered by a portion of the secondary supporting portion (102, 103), for example a portion of the secondary supporting portion (102, 103) protruding into a space bounded by an upper portion of the restraining portion (33) and a lower front end portion of the seat bottom (1202).A child seat (3), the child seat (3) comprising a support structure (1100), a seat structure (1200) comprising a seat bottom (1202) and a seat back (1204), the seat structure (1200) being supported on the support structure (1100) and configured to be transferable between a seat configuration and a reclining configuration, a locking mechanism (1220) for locking the seat structure (1200) in the seat configuration and / or the reclining configuration, the locking mechanism (1220) comprising an operating member (1222) for temporarily unlocking the locking mechanism (1220), the operating member (1222) being provided at a lower front end portion of the seat bottom (1202).A child seat (3), the child seat (3) comprising a support structure (1100), a seat structure (1200) comprising a seat bottom (1202) and a seat back (1204), the seat structure (1200) being supported on the support structure (1100) and configured to be transferable between a seat configuration and a reclining configuration, the seat back (1204) being configured to be rotatable about a fixed rotational axis defined by a first rotational connector (1208), and further comprising a locking mechanism (1220) for locking the seat structure (1200) in the seat configuration and / or the reclining configuration, the locking mechanism (1220) being configured to engage between the seat structure (1200) and the support structure (1100) in a direction transverse to the fixed rotational axis.The child seat (3) according to claim 134, wherein the locking mechanism (1220) is configured to engage in a radial direction with respect to the fixed rotation axis.The child seat (3) according to any one of claims 134 or 135, wherein the locking mechanism (1220) comprises an engagement portion (1224) configured to move between a locking position and an unlocking position, wherein the engagement portion (1224) may be provided on the seat back (1204) and / or may be arranged to be linearly movable, for example may be arranged to be linearly movable in a radial direction with respect to the fixed rotation axis or parallel to the radial direction, for example perpendicular to the fixed rotation axis and optionally offset from the fixed rotation axis, and / or may be arranged to be movable substantially perpendicular to a backrest surface portion of the seat back (1204), and / or wherein the engagement portion (1224) is configured to move in a direction comprising a rearward direction component and a downward direction component.The child seat (3) according to claim 136, wherein the support structure (1100) comprises at least two recesses (1230, 1232) for receiving the engagement portion (1224), and / or wherein the locking mechanism (1220) comprises an actuating member (1222) operatively connected to the engagement portion (1224), wherein the actuating member (1222) may be provided on the seat bottom (1202).A child seat (3), the child seat (3) comprising a belt receiving portion (1410) configured to receive a seatbelt portion of a vehicle seat for mounting the child seat (3) to a vehicle seat, a blocking portion (1420) configured to be moved between a blocking position in which insertion of the belt portion into the belt receiving portion (1410) is blocked and a releasing position in which insertion of the belt portion into the belt receiving portion (1410) is permitted, wherein the blocking portion (1420) is configured to at least partially surround a wall portion (1411) of the belt receiving portion (1410) when the blocking portion (1420) is positioned in the blocking position.The child seat (3) according to claim 138, wherein the blocking portion (1420) includes an accommodation recess (1421) for accommodating the wall portion (1411).The child seat (3) according to claim 139, wherein the recess (1421) is provided in a free end portion (1423) of the blocking member (1420).The child seat (3) according to claim 140, wherein the free end portion (1423) has a stepped configuration and / or wherein the free end portion (1423) may have an L-shape.The child seat (3) according to any one of claims 138 to 141, wherein the belt receiving portion (1410) includes an insertion region (1412) and an accommodation region (141), wherein the accommodation region (1413) may be configured to support an inserted belt portion across its entire width, wherein a dimension of the insertion region (1412) is smaller than the dimension of the accommodation region (141)), and wherein the blocking portion (1420) is configured and arranged to partially extend through the accommodation region (141) into the insertion region (1412) when positioned in the blocking position.The child seat (3) according to claim 142, wherein the blocking portion (1420) is configured to protrude at least partially from below into the belt receiving portion (1410) when positioned in the blocking position.The child seat (3) according to any one of claims 138 to 143, further comprising a seat structure (1200) comprising a seat bottom (1202) and a seat back (1204), wherein the seat structure (1200) is configured to be transferable between a seat configuration and a reclining configuration, wherein the blocking portion (1420) is operatively connected to the seat structure (1200) such that the blocking portion (1420) is moved to the blocking position when the seat structure (1200) is transferred to the reclining configuration and is moved to the release position when the seat structure (1200) is transferred to the seat configuration.The child seat (3) according to claim 143, wherein the seat back (1204) comprises a force application portion (1205), and the blocking portion (1420) comprises a force receiving portion (1422) coupled to the force application portion (1205), for example slidably supported on the force application portion (1205), wherein the blocking portion (1420) is guided along a predetermined path, for example along a straight path or a curved path, wherein the predetermined path may extend in an upward direction and / or may be provided in a support structure (1100) of the child seat (3) and may be defined by a slot (1102) provided in the support structure (1100), and wherein the support structure (1100) may comprise the belt receiving portion (1410) and / or may at least rotatably support the seat back (1204), and / or wherein the force application portion (1205) may include a slot (1206), and the force receiving portion (1422) may be slidably received in the slot (1206).A child seat (3), the child seat (3) comprising a carrying handle (1300) configured to carry the child seat (3), the carrying handle (1300) comprising a primary grip portion (1302) configured to carry the child seat (3) with a single hand and extending in a first direction, for example, in a horizontal direction of the child seat (3), and two special secondary grip portions (1312) configured to carry the child seat (3) with both hands and extending in a second direction, for example, transverse to the first direction.The child seat (3) according to claim 146, wherein the secondary grip portions (1312) are provided on the support handle such that they are arranged at the same level, and / or wherein the support handle (1300) has a U-shape with a base portion and two leg portions (1304, 1306) extending from the base portion, free end portions (1308) of the leg portions (1304, 1306) being coupled to a support structure (1100), each leg portion (1304, 1306) having one of the secondary grip portions (1312).The child seat (3) according to any one of claims 146 and 147, wherein the secondary grip portions (1312) include a shape-deviating portion in a surface of the carrying handle (1300), wherein the shape-deviating portion may include a local shape-deviation that prevents the carrying handle (1300) from slipping by a user's hand when the user carries the child seat (3) using the secondary grip portions (1312).The child seat (3) according to claim 148, wherein the shape-deviation portion may include a protrusion (1316) delimiting an upper portion of a grip region (1314), and / or wherein the shape-deviation portion includes an uneven surface created by, for example, corrugations, grooves, and / or notches.The child seat (3) according to any one of claims 146 to 147, wherein the secondary grip portions (1312) include a material deviation portion in a surface of the carrying handle (1300), the material deviation portion being configured to increase friction between a user's hand and the carrying handle (1300), and may include a rubber material.The child seat (3) according to any one of claims 146 to 150, further comprising a locking mechanism (50) for releasably locking the child seat (3) to a coupling interface (100) of a support unit (2), for example a base (2) for supporting the child seat (3) on a vehicle seat (90) or a frame of a carrier, for example a baby carriage, wherein the locking mechanism (50) comprises an operating member (1252) for temporarily unlocking the locking mechanism (50), wherein the secondary grip portions (1312) are positioned on the carrying handle (1300) such that a user can operate the operating member (1252) with a hand gripping the secondary grip portion (1312), and / or wherein the operating member (1252) and the carrying handle (1300) are configured such that, the operating member (1252) being manually operable by a user while the user grasps the carrying handle (1300) with both hands.The child seat (3) according to claim 151, wherein the carrying handle (1300) is rotatably arranged between a carrying position and a non-carrying position, wherein the secondary grip portions (1312) are arranged on the carrying handle (1300) such that a user can operate the operating members (1252) with the thumb of a hand while gripping the secondary grip portion (1312) with the fingers of the hand when the carrying handle (1300) is in the carrying position, and / or wherein the secondary grip portions (1312) are arranged on the carrying handle (1300) such that adjacent operating members (1252) are positioned at the same level as the secondary grip portions (1312) when the carrying handle (1300) is in the carrying position.A child seat (3), the child seat (3) comprising a first interface portion (10) releasably engageable with a first type of coupling interface, for example, a coupling interface provided on a stroller frame, a second interface portion (30) releasably engageable with a second type of coupling interface (100), for example, a coupling interface (100) of a base (2) configured to be fixed to a vehicle seat, an operating mechanism (1250) configured to simultaneously operate the first interface portion (10) and the second interface portion (30) to transition the interface portions (10, 30) to a release state.The child seat (3) of claim 153, wherein the first interface portion (10) comprises a rotary lock mechanism and the second interface portion (30) comprises a translation lock mechanism, and wherein the actuation mechanism (1250) is configured to translate a rotational input force into a rotational movement in the rotary lock mechanism and a translational movement in the translation lock mechanism.The child seat (3) according to claim 154, wherein the rotary locking mechanism comprises a rotationally movable locking member (1264), and / or wherein the rotationally movable locking member (1264) comprises an engagement portion (1266) comprising, for example, a hook and a force receiving portion (1267) for receiving an actuation force, and / or wherein the rotationally movable locking member (1264) is configured as a lever rotatably attached to the child seat (3) by means of a rotary connector (1258), wherein the rotary connector defines a lever rotation axis, wherein the engagement portion (1266) and the force receiving portion (1267) are arranged on opposite sides of the rotary connector (1258), and / or wherein the force receiving portion (1267) is configured on one side for sliding contact with a force applying portion (1257) and / or is configured, In order to receive a restoring force from a restoring spring (1256) on an opposite side.The child seat (3) according to any one of claims 153 to 155, wherein the translation locking mechanism comprises a translation movable engagement portion (51, 52), for example a locking member (54), wherein the engagement portion (51, 52) can be arranged radially into and movable out of a recess (31) of the second interface portion (30), wherein the recess (31) can be provided in a bottom portion of the second interface portion (30), and / or wherein the recess (31) can extend in a first direction (D1) extending in a direction opposite to an insertion direction of the child seat (3) on the second type of coupling interface (100), and / or wherein the recess (31) can be configured to receive a primary support portion (101) protruding from a base (2) in the first direction (D1).The child seat (3) according to any one of claims 153 to 156, wherein the actuation mechanism (1250) comprises an actuation member (1252) which is force-transmittingly coupled to the first interface portion (10), for example to the rotationally movable locking member (1264), and / or to the second interface portion (30), for example to an engagement portion (51, 52) of the second interface portion (30), in particular to a locking member (54) of the second interface portion (30), wherein the actuation member (1252) can be force-transmittingly coupled to the second interface portion (30) by means of a force-transmitting member (1262), and / or wherein the force-transmitting member (1262) can be configured to transmit a tensile force to the second interface portion (30), and / or wherein the force-transmitting member (1262) can be a flat member, and / or wherein the flat member may have a ribbon-like configuration, and / or wherein the flat member may have a substantially rectangular cross-section.The child seat (3) according to claim 157, wherein the force transmission member (1262) is coupled to the engagement portion (51, 52) at at at least two positions, for example at laterally opposite sides of the engagement portion (51, 52), such that a total force applied to the force transmission member (1262) is distributed to at least two of the at least two positions.The child seat (3) according to claim 158, wherein the force transmission member (1262), for example each force transmission member (1262), comprises a branching end portion (1268), wherein the branching end portion (1268) comprises a first branching portion (1269) coupled to the engagement portion (51, 52) at a first position and a second branching portion (1270) coupled to the engagement portion (51, 52) at a second position, and / or wherein the branching end portion (1268) can be formed as an integral part, for example from plastic or metal, and / or wherein the branching end portion (1268) is coupled to a single engagement portion (51, 52), and / or wherein the first position and the second position can be offset from each other in a direction perpendicular to a movement direction of the engagement portion (51, 52), and / or wherein the first position and the second position may be laterally offset from each other in a direction perpendicular to a moving direction of the engaging portion (51, 52), and / or wherein the branch end portion (1268) forms a Y-shaped branch.The child seat (3) according to any one of claims 157 to 159, wherein the force transmission member (1262) is supported on a support structure (1100) of the child seat (3), for example supported on one side, for example supported slidingly on the support structure (1100), in particular by a surface contact with one or more support sections (1110) provided on the support structure (1100), wherein the one or more support sections (1110) may be curved, and wherein each of the first branch section (1269) and the second branch section (1270) may be supported slidingly on different support sections (1110), wherein the force transmission member (1262) may be configured to be supported on the support structure (1100) only via the branch sections (1269, 1270), and / or wherein the support structure (1100) comprises two support sections (1110), wherein each support portion (1110) is associated with a single branch portion (1269, 1270) and is configured to support the single branch portion (1269, 1270).The child seat (3) according to any one of claims 153 to 160, wherein the actuation mechanism (1250) comprises an actuation member (1252) configured to rotate when receiving a user-applied pressing force, wherein the actuation member (1252) may be configured for thumb actuation by a user, and / or wherein the actuation member (1252) is hingedly coupled to a support structure (1100) of the child seat (3), and / or wherein the actuation member (1252) comprises a lever, wherein the lever may be hingedly coupled at a first end portion to a support structure (1100) of the child seat (3), for example by means of a rotary connector (1260), and may comprise an actuation portion at a second end portion, wherein the actuation portion protrudes from the support structure (1100) through an opening (1120), and / or wherein the rotary connector (1260) may define a rotational axis, wherein the rotational axis may be configured to extend substantially parallel to a linear direction of movement of an engagement portion (51, 52), and / or wherein the rotational axis may be configured to extend skew to a linear direction of movement of an engagement portion (51, 52), wherein the actuation member has an actuation surface to receive an actuation force from a user, wherein the actuation surface may extend perpendicular to an upper edge of the support structure (2100), and / or wherein the actuation surface may be configured to receive an actuation force in a direction tangential to the upper edge of the support structure (2100), and / or wherein the actuation member (1252) may be configured between a locking position, in which an actuation portion thereof may extend in a substantially vertical direction, and a release position, in which the actuating member (1252) is rotated from the locking position by a predetermined angle, wherein the locking position can be a forward position of the actuating member (1252) on the child seat (3) and the release position can be a rearward position of the actuating member (1252) on the child seat (3), and / or wherein the actuating member (1252) has a force application portion (1253), and / or wherein the force application portion (1253) is configured to contact an intermediate force transmission member (1254), and / or wherein the force application portion (1253) is provided between the first end portion and the second end portion of the actuating member (1252), and / or wherein the force application portion (1253) has a protruding portion, and / or wherein the protruding portion extends in a direction transverse to an imaginary line, which extends through the first end portion and the second end portion, and / or wherein the protruding portion extends in the rearward direction of the child seat, and / or wherein the protruding portion is defined by a curved portion in the actuating member (1252), wherein the curved portion may be configured to extend around a rotational center of a backrest portion of the child seat when the actuating member is in the locking position, and / or wherein the force applying portion (1253) has a rearward contact surface configured to be in sliding contact with or to come into sliding contact with a force transmitting member (1254).The child seat (3) according to any one of claims 153 to 161, further comprising an intermediate force transmission member (1254), wherein the intermediate force transmission member (1254) is configured to receive a force from an actuating member (1252) and distribute the received force to the force transmission member (1262) and the rotationally movable locking member (1264), and / or wherein the intermediate force transmission member (1254) may be configured as a lever, wherein the lever may comprise a first arm portion (1257) and a second arm portion (1259), wherein the first arm portion (1257) and the second arm portion (1259) may extend at an angle to each other, and / or wherein the first arm portion (1257) and the second arm portion (1259) may extend from different sides of a rotating portion of the intermediate force transmission member (1254), wherein the rotating portion may be rotatably coupled to a support structure (1100) of the child seat (3) by means of a rotating connector (1255), and / or wherein the intermediate force transmission component (1254) comprises a force receiving portion for receiving a force from the actuating component (1252), wherein the force receiving portion may form an upper portion of the intermediate force transmission component (1254), and / or wherein the force receiving portion is provided on the first arm portion (1257), and / or wherein the force receiving portion may extend upward from the rotating connector (1255), and / or wherein the force receiving portion may comprise a first contact surface, wherein the force receiving portion may comprise a second contact surface, wherein the first contact surface and the second contact surface may be provided on opposite sides of the intermediate force transmission component (1254), wherein the first contact surface may be configured for sliding contact with a force application portion (1253) of the actuating member (1252), wherein the second contact surface may be configured for sliding contact with a force receiving portion (1267) of the rotatably movable locking member (1264), wherein the intermediate force transmission member (1254) is rotatably coupled to the force transmission member (1262).The child seat (3) according to any one of claims 153 to 162, wherein the operating member (1252), the intermediate force transmitting member (1254), and the rotatably movable locking member (1264) are rotatable about respective rotation axes, wherein the rotation axes may extend parallel to each other, and / or wherein, when the operating member (1252) is in the locking position, a connection point at which the second arm portion (1259) is connected to the force transmitting member (1262) is positioned within an imaginary triangle formed by connecting the rotation axes in a plane perpendicular to the rotation axes.A child seat (3) comprising a seat pan (2114) providing a housing space for a child, an inner impact absorber (2120) comprising a first impact protection portion (2126) configured to reduce an impact on a shoulder of a seated child in case of a side impact, wherein the first impact protection portion (2126) comprises regions having different damping characteristics.The child seat (3) according to claim 164, wherein the regions having different damping properties are provided by regions having different material rigidity in the inner impact damper (2120).The child seat (3) according to any one of claims 164 and 165, wherein the first impact protection portion (2126) has an upper end portion and a lower end portion, the lower end portion being disposed on the seat shell (2114) closer to the hip area of a seated child than the upper end portion, the upper end portion being configured more rigid than the lower end portion.The child seat (3) of claim 166, wherein the lower end portion is configured to catch the shoulder of a child having a first size, for example a child having a minimum allowable size for the child seat (3), and the upper end portion is configured to catch the shoulder of the child having a second size greater than the first size, for example a maximum allowable size for the child seat.Child seat (3) according to any of claims 164 to 167, wherein the different damping properties are provided by mechanical weakening sections in a material, for example recesses, grooves, holes.The child seat (3) according to any one of claims 164 to 168, wherein the first impact protection portion (2126) is integrally formed.Child seat (3) according to any of claims 164 to 169, wherein the inner impact damper (2120) comprises a foam material, for example a closed cell foam material, in particular expanded polypropylene, for example with a density of substantially 30 g / l.A child seat (3) comprising a seat structure (2100) defining an interior accommodation space for a child, and a side impact protection assembly (2160) configured to initiate a seating movement and / or a head movement of a seated child about the vertical axis in the event of a side impact.The child seat (3) according to claim 171, wherein the side impact protection assembly (2160) includes an outer rear side bumper (2162) supported on an outer side of the seat structure (2100) in a region behind the inner accommodation space.The child seat (3) according to claim 172, wherein the seat structure (2100) includes a seat shell (2114) defining the accommodation space and a support portion (2181, 2182) supporting the seat shell (2114) and defining a support surface (2184) facing a central longitudinal plane of the seat structure (2100), wherein the rear side bumper (2162) is accommodated in the support portion (2181, 2182), for example, in a reinforcing structure of the support portion (2181, 2182) so as to protrude laterally from the support portion (2181, 2182).The child seat (3) according to any one of claims 172 or 173, wherein the side impact protection arrangement (2160) further comprises an outer front side bumper (2161) supported on the seat structure (2100) at a level of a chest of a seated child and / or an inner impact damper (2120), and / or wherein the inner impact damper (2120) may be provided on the seat shell (2114) of the child seat (3) and extend along the same from a head portion of the child seat (3) down to the hip portion and / or at least up to a lower end of the chest of a seated child, and / or wherein the inner impact damper (2120) may be integrally formed of a single material, and / or wherein the inner impact damper may comprise a plastic material, and / or wherein the inner impact damper may comprise a foam material, For example, a closed cell foam material may comprise, and / or wherein the inner crash cushion (2120) may be made of expanded polypropylene, and / or wherein a density of the inner crash cushion (2120) may be substantially 30 g / L, and / or wherein recesses and / or openings (2125) may be provided in a lower end portion of the inner crash cushion (2120), and / or wherein the recesses and / or openings (2125) may comprise different shapes and sizes and may reduce the stiffness of the crash cushion in the lower end portion to a more suitable stiffness for smaller children.The child seat (3) of claim 174, wherein the rear side bumper (2162) and the front side bumper (2161) are spaced apart from each other.The child seat (3) according to claim 174 or 175, wherein the rear side bumper (2162) and the front side bumper (2161) project from the seat structure (2100) in parallel with each other, wherein the rear side bumper (2162) may have a free end portion and a fixed end portion, wherein the front side bumper (2161) may have a free end portion and a fixed end portion, wherein each free end portion may define a force receiving surface, wherein the force receiving surfaces may be positioned at substantially the same level, or wherein the force receiving surface of the rear side bumper (2162) is laterally disposed more outward than the force receiving surface of the front side bumper (2161).The child seat (3) according to any one of claims 174 to 176, wherein the side impact protection assembly (2160) is configured such that forces resulting from a side impact and acting on the child seat (3) in the lateral direction are first absorbed by the rear side bumper (2162) and / or are transferred to the seat structure (2100) to a greater extent from the rear side bumper (2162) with less impact absorption compared to the front side bumper (2161).The child seat (3) according to any one of claims 174 to 177, wherein the rear side bumper (2162) is more rigid than the front side bumper (2161), and / or wherein the rear side bumper (2162) may have a density of 50 g / L, and / or wherein the front side bumper (2161) may have a density of 27 g / L, and / or wherein the rear side bumper (2162) may protrude further in the lateral direction than the front side bumper (2161), and / or wherein the front side bumper (2161) and / or the rear side bumper (2162) include or may be made of EPS material.A child seat (3) comprising a seat pan (2114) providing an inner accommodation space for a child, an outer side impact protection assembly provided on an outer side of the seat pan (2114) and configured to, in the event of a side impact, attenuate an impact on the seat pan (2114) in a region of a rib cage of a seated child, wherein the outer side impact protection assembly comprises a front side bumper (2161) configured as an impact absorber and supported on the seat pan (2114) at the level of a rib cage of a seated child, wherein the front side bumper (2161) is configured such that a lower end portion thereof provides a lower rigidity compared to an upper portion thereof.The child seat (3) according to claim 179, wherein the front side bumper (2161) is configured and arranged so that its dimension is reduced toward its lower end portion.The child seat (3) according to claim 179, wherein the front side bumper (2161) has a wider upper end portion and a narrower lower end portion, wherein the shape of the front side bumper (2161) may be triangular or drop-shaped.The child seat (3) according to any one of claims 179 to 181, further comprising an inner impact absorber (2120) configured to reduce an impact on a seated child's shoulder in the event of a side impact, wherein the front side bumper (2161) and the inner impact absorber (2120) are arranged in series such that forces resulting from a side impact are transmitted through both the front side bumper (2161) and the inner impact absorber (2120).The child seat (3) according to claim 182, wherein the inner impact absorber (2120) comprises a first impact protection portion (2126) configured to reduce impact on a seated child's shoulder in the event of a side impact and comprising regions having different damping characteristics.The child seat (3) according to claim 183, wherein the first impact protection portion (2126) has an upper end portion and a lower end portion, the lower end portion being disposed on the seat shell (2114) closer to the hip region of a seated child than the upper end portion, the upper end portion being configured more rigid than the lower end portion.The child seat (3) according to any one of claims 182 to 184, wherein the front side bumper (2161) comprises or consists of a material having a lower density than the inner impact bumper (2120).A child seat (3) comprising a headrest assembly (2300) configured to reduce acceleration of a head of a seated child in the event of a side impact, wherein the headrest assembly (2300) comprises a head movement inducing structure.The child seat (3) of claim 186, wherein the head movement inducing structure is configured such that when the head of a seated child contacts the head restraint assembly (2300) as a result of a side impact, rolling movement of the head of the child is induced to at least partially reduce acceleration of the head, wherein the head movement inducing structure may be configured to induce a predetermined rolling movement sufficient to reduce acceleration of the head while simultaneously preventing excessive increase of forces acting on the neck of the seated child.The child seat (3) according to claim 187, wherein the headrest assembly (2300) comprises a headrest portion (2320) comprising a rear inner support surface (2330) and inner lateral support surfaces, for example a left inner support surface (2332) and a right inner support surface (2334), wherein each of the inner lateral support surfaces (2332, 2334) may be formed in a convex shape in a cross section along a vertical plane extending in a lateral direction of the headrest assembly (2300), and / or wherein the inner lateral support surfaces (2332, 2334) may be configured to bulge towards the inner accommodation space, and / or wherein each of the inner lateral support surfaces (2332, 2334) may comprise a lower surface portion (2340) and an upper surface portion (2344) connected to each other by a rounded tip portion (2342), wherein each tip portion (2342) is provided at a position of the inner lateral support surfaces (2332, 2334) that, when the head support portion (2300) is correctly adjusted to the size of a seated child, is disposed between an upper end portion and a center of the head of a seated child.The child seat (3) according to claim 188, wherein the headrest portion (2320) includes a lateral head support portion (2324, 2326) having the lateral support surface (2332, 2334) on an inner side, the lateral head support portion (2324, 2326) being configured to decrease a hardness thereofA child seat (3) comprising a headrest assembly (2300), and a headrest impact protection assembly configured to capture the headrest assembly (2300) in the event of an impact, wherein the headrest impact protection assembly is configured to provide a cushioning effect on the headrest assembly in a side impact direction and / or in a rear impact direction.The child seat (3) of claim 190 wherein the headrest impact protection assembly includes a headrest impact protection portion (2128) shaped corresponding to a rear portion of the headrest assembly (2300).The child seat (3) of claim 191, wherein the headrest impact protection portion (2128) has an inner surface (2123) facing the headrest assembly (2300), and the headrest assembly (2300) has an outer surface (2310) facing the inner surface (2123), the inner surface (2123) and the outer surface (2310) extending at least partially substantially parallel so as to be able to come into surface contact in the event of an impact.The child seat (3) of claim 192, wherein the inner surface (2123) and the outer surface (2310) may be curved, wherein the outer surface may form a rear corner region of the headrest assembly (2300), and wherein the inner surface (2123) may extend around the rear corner region from behind the headrest assembly (2300) to a lateral side of the headrest assembly (2300).The child seat (3) of any of claims 190 to 193 wherein the headrest impact protection assembly is integrally formed with an inner impact bumper (2120), the inner impact bumper (2120) defining the headrest impact protection portion (2128) as a second impact protection portion and having a first impact protection portion (2126) providing cushioning for a seated child's shoulder portion and / or chest.The child seat (3) of claim 194, wherein the inner impact bumper (2120) is attached to a seat shell (2114) of the child seat (3) and the headrest impact protection portion (2128) protrudes further into the interior of the seat shell (2114) than the first impact protection portion (2126) to reduce the space between the headrest impact protection portion (2128) and the headrest assembly (2300).A child restraint system comprising a stationary portion, for example a portion of a main body (20) of a base (2), such as a front end portion of the main body (20), or a secondary support portion (102, 103) on the main body (20), and a movable portion, for example a restraining portion (32, 33) of a child seat (2) or an upper end portion (903) of a load leg (900), the movable portion being movable towards and away from the stationary portion, the movable portion and the stationary portion each having an edge portion (20a, 903a), the edge portions approaching each other when the movable portion is moved towards the stationary portion, at least one edge portion (20a) of the edge portions of the movable portion (900) and the stationary portion (20) comprising an elastically deformable portion (20b, 102a, 102b) or is defined by an elastically deformable portion.The infant restraint system according to claim 196, wherein the stationary portion is a front portion of the main body (20) of the base (2) to which a load leg (900) is rotatably coupled, and the movable portion is a coupling portion (902) of the load leg (900).The infant restraint system of claim 197, wherein the coupling portion (902) and / or the main body (20) are configured such that a transition between their outer surfaces is substantially seamless when the load leg (900) is in a use position, wherein the coupling portion (902) and / or the main body (20) includes an elastically deformable lip or strip, for example a rubber lip or strip, attached to the rim portion (20a).The child restraint system according to any one of claims 196 to 198, wherein the stationary portion is a secondary support portion (102, 103) on the main body (20), and wherein the movable portion is a child seat restraining portion (32, 33) engageable with the secondary support portion (102, 103), the secondary support portion (102, 103) including the elastically deformable portion (103a) made of, for example, rubber, the elastically deformable portion (103a) being provided at least on a portion of the secondary support portion (102, 103) facing toward an entering restraining portion (32, 33) and configured to protrude from a supporting structure (600) of the secondary support portion (102, 103), for example to protrude laterally from a supporting structure (600) of the secondary support portion (103), so as to project further outward from the secondary support portion than the rigid portion.The infant restraint system according to claim 199, wherein the elastically deformable portion (103a), for example a cover, protrudes laterally from the secondary support portion (102, 103) such that the restraint portion (32, 33), when moving into the secondary support portion (102, 103), must first pass the elastically deformable member (103a).The child restraint system according to claim 198 or 199, wherein the elastically deformable portion (103a) comprises a cover covering an upper side of a free end portion of the secondary support portion (102, 103) such that any rigid member or any edge of such member is positioned further within the deformable portion or the cover in a direction of movement of the restraint portion.The infant restraint system of any one of claims 196 to 201, wherein the elastically deformable portion has a hardness of 80 Shore A or less and / or comprises a thermoplastic elastomer material, for example TPE-S or SEBS.A base (2) for a child restraint system (1) comprising a primary support portion (101) protruding from an upper surface portion (118) of the base (2) in a first direction (D1), the primary support portion (101) being configured to support a child seat (3) rotatably about an axis of rotation (R1) extending parallel to the first direction (D1), the upper surface portion (118) comprising, adjacent to the primary support portion (101), at least one further protrusion (118a), for example a bead and / or a rib, extending over a predetermined angular range about the axis of rotation (R1) and being configured to prevent excessive surface contact between a lower surface of the child seat (3) and the upper surface portion (118).The base (2) of claim 203, wherein the protrusion extends along a curved path, wherein the curved path may be circular.The base (2) according to claim 203 or 204, wherein the top surface portion (118) comprises two or more protrusions (118a) extending along at least two different concentric circles about the axis of rotation (R1).Base (2) according to claim 205, wherein the protrusions are offset from each other and / or extend between different angular positions about the rotation axis (R1) and / or wherein protrusions () extending along different concentric circles at least partially overlap each other in the radial direction.A child seat (3) couplable to a base (2), the child seat (3) comprising an interface portion (30) provided at a bottom of the child seat and releasably engageable with a primary support portion (101), the interface (30) comprising a recess (31) configured to receive the primary support portion (101) in a first direction (D1) and a support surface (34) configured to contact a longitudinal end portion of the primary support portion (101) and a lower surface portion extending around the interface portion (30), the lower surface portion comprising at least one protrusion, for example a bead and / or a rib, extending over a predetermined angular range around the interface portion (30) and / or around a rotation axis (R1), which is defined by the interface portion (30), wherein the at least one protrusion is configured to prevent excessive surface contact between an upper surface portion (118) of the base (2) and a lower surface portion of the child seat.The child seat (3) according to claim 207, wherein the protrusion extends along a curved path, wherein the curved path may be circular.Child seat (3) according to claim 207 or 208, wherein the lower surface portion comprises two or more protrusions extending along at least two different concentric circles around the interface portion (30) and / or around the rotation axis (R1).Child seat (3) according to claim 209, wherein the projections are offset with respect to one another and / or extend between different angular positions around the interface portion (30) and / or around the axis of rotation (R1) and / or wherein projections extending along different concentric circles at least partially overlap one another in the radial direction.A child seat (3), wherein the child seat (3) comprises a belt receiving portion (1410) configured to receive a seat belt portion of a vehicle seat for mounting the child seat (3) to a vehicle seat, a blocking portion (1420) configured to be moved between a blocking position in which insertion of the belt portion into the belt receiving portion (1410) is blocked and a releasing position in which insertion of the belt portion into the belt receiving portion (1410) is allowed, wherein the receiving portion (1410) comprises a recess (1415), and wherein a free end portion (1423) of the blocking portion (1420) is received in the recess (1415) when the blocking portion (1420) is in the blocking position.The child seat (3) according to claim 211, wherein the blocking portion (1420) is configured to protrude at least partially from below into the belt receiving portion (1410) when positioned in the blocking position.Child seat (3) according to claim 211 or claim 212, wherein the blocking portion (1420) is linearly movable, wherein the blocking portion (1420) can be supported on a carrier (1426), for example can be supported on the carrier (1426) by means of a spring (1427), wherein the carrier (1426) is linearly guided and the blocking portion (1420) is linearly guided on the carrier (1426), for example in a guide recess (1428).The child seat (3) according to any one of claims 211 to 213, further comprising a seat structure (1200) comprising a seat bottom (1202) and a seat back (1204), wherein the seat structure (1200) is configured to be transferable between a seat configuration and a reclining configuration, wherein the blocking portion (1420) is operatively connected to the seat structure (1200) such that the blocking portion (1420) is moved to the blocking position when the seat structure (1200) is transferred to the reclining configuration and is moved to the release position when the seat structure (1200) is transferred to the seat configuration.The child seat (3) according to claim 214, wherein the seat back (1204) comprises a force application portion (1205), and the blocking portion (1420) comprises or is coupled in a force-receiving portion (1422) operatively connected to the force application portion (1205), for example held displaceably on the force application portion (1205), for example in a force-transmitting manner via the carrier (1426), wherein the blocking portion (1420) is guided along a predetermined path, for example along a straight path or a curved path, wherein the predetermined path can extend in an upward direction and / or can be provided in a supporting structure (1100) of the child seat (3) and can be defined by a slot (1102) provided in the supporting structure (1100), and wherein the support structure (1100) may include the belt receiving portion (1410) and / or may at least rotatably support the seat back (1204), and / or wherein the force applying portion (1205) may include a slot (1206) and the force receiving portion (1422) may be slidably received in the slot (1206).A child seat (3), the child seat (3) comprising a support structure (1100), a seat structure (1200) comprising a seat bottom (1202) and a seat back (1204), the seat structure (1200) being supported on the support structure (1100) and configured to be transferable between a seat configuration and a reclining configuration, a belt receiving portion (1430) configured to receive a seatbelt portion of a vehicle seat for mounting the child seat (3) to a vehicle seat, the belt receiving portion (1430) being disposed at a rear side of the seat back (1204), the belt receiving portion (1430) being configured to be transferable between an active configuration in which insertion of the seatbelt portion is possible and an inactive configuration in which insertion of the seatbelt portion into the belt receiving portion is not possible.The child seat (3) according to claim 216, wherein the belt receiving portion (1430) is placed in the inactive configuration when the seat structure (1200) is placed in the reclining configuration, and is placed in the active configuration when the seat structure (1200) is placed in the seating configuration.The child seat (3) according to claim 216, wherein the belt receiving portion (1430) is provided on the seat back (1204) to be integrally movable therewith, wherein the seat back (1204) is rotatably coupled to the support structure (1100) to transition the seat structure (1200) between the seat configuration and the reclining configuration, and wherein the seat back (1204) and the support structure (1100) are configured such that when the seat structure (1200) is in the reclining configuration, at least an insertion area (1431) of the belt receiving portion (1430) is covered by the support structure (1100).The child seat (3) of claim 218, wherein the seat back (1204) and the support structure (1100) are configured such that when the seat structure (1200) is in the reclining configuration, the strap receiving portion (1430) is completely covered by the support structure (1100).A trim cover (2400) for a child seat (3), for example an infant seat, the trim cover (2400) comprising: a flexible trim portion (2408) configured to cover at least an outer portion (2140) of a seat structure (2100), the flexible trim portion (2408) comprising a trim edge portion (2410); and a mounting portion (2420) for coupling the trim edge portion (2410) to the seat structure (2100), the mounting portion (2420) being coupled to the trim edge portion (2410) at a coupling region (2429), the mounting portion (2420) extending along the flexible trim portion (2408), an outer side (2428) thereof facing an inner side or inner surface (2409) of the flexible trim portion (2408), wherein an inner side or inner surface (2426) of the mounting portion (2420) has a support protrusion (2424) configured to be supported on an edge portion (2144) of the outer portion (2140).The trim cover (2400) of claim 220, wherein the coupling region (2429) is attached to the trim cover edge portion (2410) along an attachment line (2431), wherein the attachment line (2431) may extend substantially parallel to the trim cover edge portion (2410).The trim cover (2400) of claim 221, wherein the coupling region (2429) is sewn to the trim cover edge portion (2410) along a line of stitching (2435), the line of stitching forming the line of attachment (2431).The cover (2400) according to claim 221 or claim 222, wherein the support protrusion (2424) extends on the inner side of the attachment portion (2420) following the attachment line (2431), for example parallel to the attachment line (2431) and / or parallel to an imaginary straight line extending through end points of the attachment line.The cover according to any one of claims 221 to 223, wherein the support protrusion (2424) defines or comprises a support surface (2440), wherein the support surface (2440) is provided on a lateral side of the support protrusion (2424) that is facing away from the coupling region (2429).The trim cover (2400) of any of claims 221 to 224, wherein the attachment portion (2420) is coupled to the flexible trim cover portion (2408) on only one side.The trim cover (2400) of any of claims 220 to 224, wherein the support protrusion (2424) is straight.The trim cover (2400) according to any one of claims 220 to 226, wherein the attachment portion (2420) is a substantially flat rigid member, wherein the attachment portion may be substantially rectangular and / or wherein the coupling region (2429) is provided at a longitudinal end portion of the attachment portion and / or wherein the attachment line (2431) extends in a transverse direction of the attachment portion, wherein the support protrusion is provided at a position between longitudinal ends of the attachment portion.The trim cover (2400) of any of claims 220 to 227, wherein the attachment portion is configured to hook to an edge portion (2144) of a seat structure and to support the trim cover edge portion a predetermined distance from the edge portion (2144) of the seat structure.A child seat (3) comprising a seat shell (1114) providing an inner accommodation space for a child, an outer side impact protection arrangement provided on an outer side of the seat shell (1114) and configured to, in case of a side impact, cushion an impact on the seat shell (1114) in a region of a rib cage and / or in a region of the head of a seated child, wherein the outer side impact protection arrangement comprises an impact damper (1281) held on the seat shell (1114), wherein the impact damper (1281) extends laterally outwards from the seat shell (1114) in the transverse direction of the child seat (3), and wherein the impact damper (1281) tapers towards its laterally outermost portion (1285) and / or tapers towards a front end portion (1284).The child seat (3) according to claim 229, wherein the impact damper (1281) at least partially gradually tapers towards its laterally outermost portion (1285) and / or at least partially gradually tapers towards its laterally outermost portion (1285).The child seat (3) according to claim 229, wherein an outer side (1286) of the impact damper (1281) is provided as a relief to provide different cushioning properties in different areas on the outer side (1286).The child seat (3) according to claim 231, wherein the cushioning properties are distributed such that a side impact on the impact damper (1281), applied for example by an imaginary planar force application surface extending perpendicular to a transverse direction of the child seat, is optionally first slightly cushioned in an intermediate portion by compressing the intermediate portion in the transverse direction of the child seat (3) to a level at which the force application surface contacts a stiffer rear portion of the impact damper, then presses on the rear portion (1282), thereby inducing rotation in the seat structure, optionally wherein the intermediate portion (1283) is then further compressed with gradually increasing stiffness due to the tapered shape of the impact damper (1281).The child seat (3) according to any one of claims 229 to 232, wherein an elongated central portion (1287) elevated above an adjacent upper portion (1288) and / or an adjacent lower portion (1289) of the impact absorber (1281) extends at least partially from a front end portion (1284) to a rear end portion (1282) of the impact absorber (1281).The child seat (3) according to any one of claims 229 to 233, wherein the impact absorber (1281) has an outwardly curved shape having an arcuate outer surface portion extending from the rear end portion (1282) to the front end portion (1284), the arcuate outer surface portion being capable of being provided at the elongated central portion (1287).The child seat (3) according to any one of claims 229 to 234, wherein the outermost lateral portion (1285) is provided in an intermediate portion (1283) of the impact absorber (1281) between the front portion (1284) and the rear portion (1282).The child seat (3) according to any one of claims 229 to 235, wherein the impact absorber (1281) is integrally formed of a single material.The child seat (3) according to any one of claims 229 to 236, wherein a rear portion (1282) of the impact absorber (1281) has a higher rigidity than the front end portion.A child seat (3) comprising a seat pan (1114) providing an inner accommodation space for a child, an outer side impact protection assembly provided on an outer side of the seat pan (1114) and configured to, in case of a side impact, cushion an impact on the seat pan (1114) in a region of a rib cage and / or in a region of the head of a seated child, wherein the outer side impact protection assembly comprises an impact damper supported on the seat pan (1114), wherein the impact damper comprises a rear end portion and a front end portion, and wherein the rear end portion has a higher rigidity than the front end portion.A headrest assembly (1500) for a child seat (3) comprising a headrest base body (1502) having a rear wall (1504) and two side walls (1506, 1508) defining an inner accommodation space for the head (H) of a seated child, and a first cushioning portion (1510) provided at a rear inner region of the side walls and a second cushioning portion (1512, 1514) provided at a front region of the side walls (1506, 1508), wherein the second cushioning portion (1512, 1514) continues from a front end portion (1516) of the first cushioning portion (1510).Headrest arrangement (1500) according to claim 239, wherein the second damping portion (1512, 1514) comprises a coupling portion (1520) at least partially inserted into a receiving space (1505) provided between the base body (1502) and the first damping portion (1510), for example in a recess (1518), for example two recesses formed in the base body (1502), wherein the coupling portion may comprise a protrusion (1522, 1524), for example two or more protrusions, inserted into the recess or recesses.Headrest arrangement (1500) according to one of claims 239 and 238, wherein a transition (1526) from the first damping portion (1510) to the second damping portion (1512, 1514) is at least partially stepped, wherein a rear end portion (1528) of the second damping portion (1512) protrudes beyond an inner contour of the adjacent first damping portion (1510) at the front end portion (1530) of the first damping portion (1510), for example such that a sharp edge (1532) is provided by the second damping material (1512), wherein the sharp edge (1532) can extend in or along a plane.The headrest assembly (1500) according to any one of claims 239 to 241, wherein a rear surface portion (1534) of the second damping portion (1512) and a front surface portion (1536) of the first damping portion (1510) face each other and / or extend parallel to each other, for example along a reference plane extending in the transverse direction of the headrest assembly, wherein the reference plane may extend perpendicular to a vertical central plane of the headrest base body (1502).The headrest assembly (1500) according to any one of claims 239 to 242, wherein the headrest base body (1502) is U-shaped with a base and two legs when viewed from above, wherein the base is formed by a rear portion of the headrest base body (1502) and the legs are formed by two side portions of the headrest base body (1502), wherein the rear portion has the rear wall (1504) and each side portion has a side wall (1506, 1508), wherein the headrest base body (1502) has a main extension direction (M) transverse to the extension directions of the legs from the base, and wherein the reference plane (1540) may extend at an angle with respect to the main extension direction (M), for example such that an upper portion is arranged further in the forward direction than a lower portion.The headrest assembly (1500) of any one of claims 239 to 243, wherein a rear cavity (1550) is provided between a rear lower portion (1511) of the first cushion portion (1510) and a portion of the headrest base body (1502).Headrest arrangement (1500) according to any of claims 239 to 244, wherein the first cushioning portion (1510) is made of an expanded foam material, for example EPP, and / or wherein the second cushioning portion (1512, 1514) is made of a polyurethane material, for example PU foam.A headrest assembly (2300), comprising a headrest base body (2302) having a rear wall (2350) and two side walls (2352, 2354) defining an inner accommodation space for the head (H) of a seated child, and an impact absorbing portion (2320) provided at an inner side of the headrest base body (2302), wherein the impact absorbing portion (2320) is integrally formed of a single material, for example, an expanded foam material such as EPP, wherein a side portion (2360, 2362) of the impact absorbing portion (2320) extending along the side wall (2352, 2354) has a trough-like recess (2530) at an outer side thereof.The headrest assembly (2300) of claim 246, wherein the trough-like recess (2530) provides an inner wall portion (2364, 2366) having reduced material thickness in the impact damping portion (2320), and wherein a cavity is created between the inner wall portion (2364, 2366) and the side wall (2532, 2534) to provide a region of reduced stiffness and / or hardness of the side portion and / or increased flexibility.The headrest assembly (2300) of any of claims 246 and 247, wherein a rear portion of the trough-like recess is defined by an oblique planar surface (2368) or a curved surface extending such that a material thickness increases in a rearward direction of the impact absorbing portion (2320) towards a rear portion (2370, 2372) of the side portion (2360, 2362), wherein the oblique planar surface (2368) may extend at an angle with respect to a vertical central plane of the impact absorbing portion (2320), for example at an angle of 45 degrees or less.The headrest assembly (2300) of claim 246 or 247, wherein a rim portion (2536, 2538) extending at least partially around an opening of the trough-like recess contacts the headrest base body (2302).The headrest assembly (2300) of any of claims 246 to 249, wherein the headrest base body (2302) and the impact absorbing portion (2320) have a U-shape, each side portion (2360, 2362) defining a leg of the U-shape.The headrest assembly (2300) of any of claims 246 to 250, wherein the trough-like recess (2530) extends over more than half the length of the side portion (2360, 2362) between a front end of the side portion and a rear end of the side portion and / or over more than half the width of the side portion (2360, 2362) between a lower end and an upper end of the side portion.The headrest assembly (2300) of any of claims 246 to 251, wherein the trough-like recess tapers inwardly in the transverse direction of the headrest assembly (2300) and / or tapers towards a front end of the side portion (2360, 2362).The headrest assembly (2300) according to any one of claims 246 to 252, wherein the trough-like recess has a volume of 50 ml or more, for example 100 ml or more or 200 ml or more.A child seat (3) comprising a seat structure (2100) having a backrest portion (2104), the backrest portion (2104) comprising a rigid backrest base body (2114), for example a seat shell, and an inner padding (2120), and a headrest assembly (2300) comprising a flexible side portion (2360, 2362) configured to flex outwards during a side impact, wherein the inner padding (2120) comprises a headrest portion (2121) provided at a side portion of the backrest base body (2114) in the region of the headrest assembly (2300), and an adjacent portion (2122), for example a shoulder portion or an upper arm contacting portion extending at least below the headrest portion (2121) along a narrow side of the headrest portion (2121) at the side portion of the backrest body (2114), wherein a hardness or rigidity or density of the headrest portion (2121) is lower than a hardness or rigidity or density of the adjacent portion (2122).The child seat (3) according to claim 254, wherein a transition from an inner surface of the adjacent portion (2122) to an inner surface of the headrest portion (2121) is continuously and / or substantially seamless.The child seat (3) according to any one of claims 254 and 255, wherein the headrest portion (2121) partially forms an end edge of the cushion (2120).The child seat (3) according to any one of claims 254 to 256, wherein the adjacent portion (2122) and the headrest portion (2121) comprise a foam material, wherein the adjacent portion (2122) may comprise a closed cell foam material, for example EPP, optionally with a density of substantially 30 g / l, and wherein additionally or alternatively the headrest portion (2121) may comprise an open cell foam material.

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