Achieving defined exposure distance settings in the hair-cutting unit of a rotary electric shaver

Abstract

In a hair-cutting unit for a rotary electric shaver of the type comprising an external cutting member 10, an internal cutting member and a support member 30, the exposure distance by which the skin-contacting surface of the shaving track of the external cutting member 10 projects relative to the upper surface of the support member 30 is adjustable. For this purpose, an adjustment system is provided, which comprises, inter alia, at least one adjustment set of guide grooves and driven elements 42 engaging in said guide grooves, as well as an initial position setting system configured to enable synchronization of the exposure distance settings between a number of hair-cutting units, during which an initial position of the driven elements 42 in the guide grooves, defined by the stops of said guide grooves, is achieved and maintained.

Description

[Technical field]

[0001] The present invention relates to a hair-cutting unit for a rotary electric shaver, comprising: - an external cutting element provided with a shaving track having a hair entry opening; - an inner cutting member covered by the outer cutting member and rotatable relative to said outer cutting member about a central axis of the hair-cutting unit; - a support member surrounding and supporting the external cutting member; and - an adjustment system for adjusting an exposure distance over which a skin contact surface of a shaving track protrudes relative to an upper surface of a support member, the adjustment system comprising an adjustment actuator and an adjustment transmission system, via which the adjustment actuator is able to adjust the exposure distance via a relative rotation of an external cutting member and a support member about a central axis, the adjustment transmission system comprising a conversion mechanism for converting the relative rotation of the external cutting member and the support member about the central axis into a relative axial movement of the external cutting member and the support member in an axial direction parallel to the central axis; having - the conversion mechanism has at least one set of guide grooves and a driven element engaged with the guide grooves; - the guide groove is inclined with respect to an imaginary plane perpendicular to the central axis and is provided on one of i) an inner surface of the support member surrounding the outer cutting member and ii) an outer peripheral surface of the outer cutting member; and a driven element is provided on the other of i) said inner surface of the support member and ii) said outer circumferential surface of the outer cutting member;

[0002] Furthermore, the present invention relates to a shaving assembly comprising at least two of the above-mentioned hair-cutting units and a base unit supporting said at least two hair-cutting units, and also to a rotary electric shaver comprising such a shaving assembly and a main body, the base unit of the shaving assembly being connected to the main body. [Background technology]

[0003] Rotary electric shavers and shaving assemblies for rotary electric shavers are well known. Rotary electric shavers are typically used for shaving body hair, which may be facial hair, and are powered by a mains power source and / or an electrical energy storage device, such as a battery.

[0004] In a commonly known configuration, a shaving assembly includes an assembly of a base unit and at least one hair-cutting unit supported by the base unit. Traditionally, a hair-cutting unit includes a combination of an external cutting member having a shaving track with a hair entry opening as a non-driven part and an internal cutting member as a driven part, at least the internal cutting member having one or more cutting edges. In such a case, the use of a shaving assembly incorporated in a rotary electric shaver involves setting the shaving assembly in an operating mode in which the internal cutting member of the hair-cutting unit is actually moved, and moving the shaving assembly over the skin so that the shaving track of the external cutting member of the hair-cutting unit faces and contacts the skin. In this process, hairs protruding from the skin are captured in the internal space of the hair-cutting unit, where they are abutted against the external cutting member at the position of the hair entry opening and are cut when they meet the cutting edge of the rotating internal cutting member.

[0005] An ongoing challenge in the field of rotary electric shavers is the search for practical ways to combine high comfort with high shaving performance, in particular with a high degree of closeness. Advantageously, the hair-cutting unit is designed in such a way that the user is offered the possibility to adjust the exposure distance, at which the skin-contacting surface of the shaving track protrudes relative to the upper surface of the support member, according to personal requirements. Generally speaking, a large exposure distance is associated with a high degree of closeness at the expense of comfort, whereas a small exposure distance is associated with a high degree of comfort at the expense of a closeness.

[0006] In the art, various types of adjustment systems are known for adjusting the exposure distance in a hair-cutting unit. As mentioned above, the present invention is in the field of adjustment systems having an adjustment actuator and an adjustment transmission system enabling the adjustment actuator to adjust the exposure distance via a mutually relative rotation of the external cutting member and the support member about a central axis, the adjustment transmission system having a conversion mechanism for converting the mutually relative rotation of the external cutting member and the support member about the central axis into a mutually relative axial movement of the external cutting member and the support member in an axial direction parallel to the central axis. In particular, the present invention is in the field of such types of adjustment systems, and relates to: - the conversion mechanism comprises at least one pair of guide grooves and a driven element engaged with the guide grooves; - the guide groove is inclined with respect to an imaginary plane perpendicular to the central axis and is provided on one of i) an inner surface of the support member surrounding the outer cutting member and ii) an outer surface along the circumference of the outer cutting member; and a driven element is provided on the other of i) said inner surface of the support member and ii) said outer surface of the outer cutting member.

[0007] The advantage of using such a type of adjustment system is that it is not only possible to set a minimum or maximum value of the exposure distance, but also to set any possible value of the exposure distance between the minimum and maximum values, depending on the relative rotational position of the external cutting member and the support member around the central axis. Without any further measures, this means that if the hair-cutting unit is disassembled, for example for cleaning purposes and / or for replacing one or more parts, and then reassembled, the initial exposure distance setting obtained at that time will be indefinite. In a situation where there are two or more hair-cutting units in the shaving assembly, this will cause the initial exposure distances of each hair-cutting unit to be different from each other, which will be understood to be undesirable. Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a way to synchronize the exposure distance settings between hair-cutting units, preferably without introducing complex and expensive parts into the design of the hair-cutting units and / or without having to increase the dimensions of the hair-cutting units. Also, when there is only a single hair-cutting unit in a shaving assembly, it is desirable to have the option to set a defined initial value of the exposure distance after assembly and disassembly of the hair-cutting assembly, especially if the exposure distance setting should be done automatically. In view of this, the object of the present invention may be to provide a way to achieve a defined exposure distance setting, preferably without introducing complex and expensive parts into the design of the hair-cutting units and / or without having to increase the dimensions of the hair-cutting units. [Means for solving the problem]

[0009] The present invention provides a hair-cutting unit for a rotary electric shaver, the hair-cutting unit comprising: - an external cutting element provided with a shaving track having a hair inlet; - an inner cutting member covered by the outer cutting member and rotatable relative to said outer cutting member about a central axis of the hair-cutting unit; - a support member surrounding and supporting the external cutting member; and - an adjustment system for adjusting an exposure distance over which a skin contact surface of a shaving track protrudes relative to an upper surface of a support member, the adjustment system comprising an adjustment actuator and an adjustment transmission system, via which the adjustment actuator is able to adjust the exposure distance via a relative rotation of an external cutting member and a support member about a central axis, the adjustment transmission system comprising a conversion mechanism for converting the relative rotation of the external cutting member and the support member about the central axis into a relative axial movement of the external cutting member and the support member in an axial direction parallel to the central axis; having - the conversion mechanism has at least one set of guide grooves and a driven element engaged with the guide grooves; - the guide groove is inclined with respect to an imaginary plane perpendicular to the central axis and is provided on one of i) an inner surface of the support member surrounding the outer cutting member and ii) an outer circumferential surface of the outer cutting member; - a driven element is provided on the other of i) an inner surface of the support member and ii) an outer circumferential surface of the outer cutting member; - the guide groove has a stop device defining an initial position of the driven element in the guide groove corresponding to one of a minimum and a maximum value of the exposure distance; - the adjustment actuator is operable, in a first operating state, to realize a relative rotation of the external cutting member and the support member about a central axis in a first rotational direction, thereby obtaining a displacement of the driven element towards an initial position in the guide groove, while in a second operating state, to realize a relative rotation of the external cutting member and the support member about a central axis in a second rotational direction opposite to the first rotational direction; and - the adjustment transmission system further comprises an initial position setting system configured to stop the relative axial movement of the external cutting member and the support member during continued operation of the adjustment actuator in the first operating state when the driven element reaches an initial position in the guide groove, thereby maintaining one of the minimum and maximum values ​​of the exposure distance.

[0010] From the above definition of the hair-cutting unit according to the invention, it can be seen that the adjustment system included in said hair-cutting unit for adjusting the exposure distance is designed to be able to set one of the minimum and maximum values ​​of the exposure distance as an initial value of the exposure distance and to maintain this initial value of the exposure distance even if the relative rotation of the external cutting member and the support member with which the initial value of the exposure distance was initially obtained continues. As defined, the adjustment transmission system of said adjustment system comprises an initial position setting system configured to stop the relative axial movement of the external cutting member and the support member with respect to each other as soon as the initial value of the exposure distance is reached as a result of the adjustment actuator being operated in the first operating state, thereby maintaining the initial value of the exposure distance. Based on the operating principle of said initial position setting system, in combination with the presence of at least one set of guide grooves of the conversion mechanism in the adjustment transmission system and a stop device in the guide groove of the driven element, the exposure distance settings in each hair-cutting unit can be synchronized even if the relative rotation of the external cutting member and the support member with respect to each other in each hair-cutting unit is realized by a common adjustment actuator of the adjustment system in a plurality of hair-cutting units. In fact, when the initial value of the exposure distance is obtained in a first unit of the plurality of hair-cutting units, the same can be performed in one or more other units of the plurality of hair-cutting units without disturbing the exposure distance setting in the first unit, since the initial position setting system of the first unit serves to stop the relative axial movement of the external cutting member and the support member. The present invention is also useful when a single hair-cutting unit is used in the shaving assembly, since the implementation of the present invention provides the possibility to realize a defined exposure distance setting in the hair-cutting unit.

[0011] What initially happens at the level of at least one set of guide grooves and driven elements is that, when the adjustment actuator is operated in the first operating state, a displacement of the driven element in the direction towards an initial position in the guide groove is obtained. If the driven element reaches an initial position in the guide groove defined by the stop device, the initial position setting system can maintain the driven element exactly in that position during the continued operation of the adjustment actuator in the first operating state. The guide grooves and the driven elements can be of any suitable design. The guide grooves can be provided as grooves in the surface, whereas the driven elements can be provided as ridge-like structures with raised positions on the surface.

[0012] In the context of the present invention, various embodiments of the initial positioning system are possible, configured to realize the above mentioned advantageous functions in a fully mechanical manner. In the following, two possibilities are defined and described, it being noted that each of the two possibilities is applicable to the embodiment of the hair-cutting unit in which the external cutting member is rotatable about a central axis relative to the support member.

[0013] According to a first possibility, the initial positioning system is configured to disable the adjustment actuator from acting on the external cutting member during the continued operation of the adjustment actuator in the first operating state when the driven element reaches the initial position in the guide groove. In a practical embodiment, the adjustment transmission system comprises a driven gear attached to the external cutting member, while the adjustment actuator comprises a drive gear engaging with the driven gear, the first and second operating states of the adjustment actuator involving corresponding opposite rotations of the drive gear in the first and second directions. In that case, the initial positioning system comprises, for each pair of guide groove and driven element, a gap in which there are no gear teeth in the drive gear, which gap is arranged with respect to the one of the guide groove and the driven element provided on the outer surface of the external cutting member, such that when the driven element is in the initial position in the guide groove, the gap faces the drive gear and the drive gear cannot drive the driven gear. Thus, the stopping of the relative movement of the guide groove and the driven element with respect to one another from the moment the driven element reaches its initial position in the guide groove, despite the continued rotation of the drive gear, is achieved on the basis of a special design of the driven gear. In order that the drive gear can again engage and drive the driven gear when the direction of rotation of the drive gear is reversed, it is advantageous for the stopping device of the guide groove of one of the at least one set of guide grooves and driven elements to comprise an elastic element arranged to urge the driven element out of its initial position in the guide groove when the driven element is in its initial position in the guide groove.

[0014] According to a second possibility, the guide groove is provided in the carrier part of the support member, and the initial positioning system is configured to allow the rotation of said carrier part together with the external cutting member about a central axis relative to the main part of the support member during the continued operation of the adjustment actuator in the first operating state, if the driven element reaches its initial position in the guide groove. Thus, stopping the relative displacement of the guide groove and the driven element relative to one another from the moment the driven element reaches its initial position in the guide groove, despite the continued rotation of the external cutting member, is achieved by providing the guide groove in the carrier part of the support member 30 and allowing said carrier part to rotate together with the external cutting member, thereby allowing a situation in which the driven element is in its initial position in the guide groove, unless the direction of rotation of the external cutting member is reversed. The initial positioning system may comprise a retaining device which holds the carrier part in a stationary position on the main part of the support member when the driven element is in a position other than the initial position in the guide groove, while allowing the carrier part to rotate about the central axis relative to the main part of the support member when the adjustment actuator operates in the first operating state and the driven element reaches the initial position in the guide groove. A practical example of such a retaining device is a retaining device which has friction structures on surfaces of the carrier part and / or the main part of the support member which are in contact with each other and extend tangentially around the central axis.

[0015] It may be practical for the guide groove to be provided on the inner surface of the support member surrounding the outer cutting member, while the driven element is provided on the outer circumferential surface of the outer cutting member, however, this does not change the fact that the invention also covers the option of the guide groove being provided on said outer circumferential surface of the outer cutting member, while the driven element is provided on said inner surface of the support member.

[0016] In order to provide the user with the opportunity to disassemble the external cutting member and the support member, it may be practical for the guide groove to have an opening through which the driven element can be removed by manually moving the external cutting member and the support member axially relative to each other. The opening may be practically arranged at a position in the guide groove that is outside the range of positions in the guide groove occupied by the driven element during normal operation of the hair-cutting unit (i.e. with an exposure distance having a value within said range from said minimum to said maximum value) as a way of preventing the driven element from becoming dislodged from the guide groove during normal operation, such as under the influence of external forces acting on the external cutting member during normal operation. In particular, the position of the opening may be such that, when viewed with respect to said range of positions occupied by the full element during normal operation of the hair-cutting unit, it is opposite to the initial position of the driven element corresponding to said one of the minimum and maximum values ​​of the exposure distance and beyond the position of the driven element corresponding to the other of the minimum and maximum values ​​of the exposure distance. Other measures aimed at preventing the driven element from falling out of the guide groove during said normal operation of the hair-cutting unit are also feasible in the context of the present invention, these measures may be structural measures.

[0017] In a practical embodiment of the hair-cutting unit according to the present invention, the conversion mechanism has three sets of guide grooves and driven elements, and the three sets are arranged at angular intervals of 120° around the central axis, which configuration ensures the stability and robustness of the hair-cutting unit.

[0018] It may be sufficient for the adjustment system to be configured to provide a relative rotation of the external cutting member and the support member to one another over a limited angle about a central axis, the limited angle being selected having regard to the angle required to vary the exposure distance between a minimum and a maximum value.

[0019] For the sake of completeness, it is noted that in the hair-cutting unit of the invention, the external and internal cutting members are drivable independently of each other, provided that the external cutting member is rotatable about a central axis.

[0020] The invention further relates to a shaving assembly comprising at least two above-mentioned hair-cutting units and a base unit supporting said at least two hair-cutting units. Advantageously, the adjustment actuator of each hair-cutting unit is configured to be operated such that when the operation of the shaving assembly is started, an operation is performed to ensure that the exposure distance is the same in all hair-cutting units. In view of the above, this means that the adjustment actuator in each hair-cutting unit is configured to be operated in said first operating state during an initial operating phase of the shaving assembly such that in each hair-cutting unit, a driven element in at least one set of guide groove and driven element can reach an initial position in the guide groove.

[0021] As indicated above, the adjustment system of the hair-cutting units may have a common adjustment actuator. In this respect, it is noted that the common adjustment actuator may have a common drive gear located centrally between the hair-cutting units. The use of a common drive gear contributes to the compactness of the hair-cutting units and is also advantageous in that the rotational drive synchronization is directly and automatically obtained.

[0022] Finally, the invention also relates to a rotary electric shaver comprising a main body and a shaving assembly as described above, the base unit of which is connected to said main body.

[0023] The above-mentioned and other aspects of the present invention will become apparent from and will be described with reference to the following detailed description of two embodiments of a hair-cutting unit having an external cutting member, an internal cutting member, a support member and an adjustment system for adjusting the exposure distance over which the skin contact surface of the shaving track of the external cutting member protrudes relative to an upper surface of the support member, the adjustment system being configured to enable synchronization of exposure distance settings between multiple hair-cutting units in a shaving assembly. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 shows a schematic perspective view of a rotary electric shaver according to an embodiment of the present invention, the rotary electric shaver comprising a shaving assembly and a main body. [Diagram 2] FIG. 2 shows a schematic perspective view of an external cutting member, a decorative cap and an internal cutting member of a hair-cutting unit in a shaving assembly, with both the external cutting member and the cap shown partially cut away. [Diagram 3] FIG. 3 shows a schematic perspective view of an external cutting member assembly including an external cutting member, a driven gear attached to the external cutting member, and a driven element disposed on the external cutting member. [Figure 4] FIG. 4 shows certain exposure distance settings for a hair-cutting unit. [Diagram 5] FIG. 5 shows another exposure distance setting for the hair-cutting unit. [Figure 6] FIG. 6 shows a schematic perspective view of a support member of a hair-cutting unit according to a first practical embodiment of the present invention. [Figure 7] FIG. 7 shows a schematic bottom view of the external cutting member assemblies and support members of the three hair-cutting units according to a first practical embodiment of the present invention, as well as a common drive gear. [Figure 8] FIG. 8 shows diagrammatically a perspective view of an external cutting member assembly of a hair-cutting unit according to a first practical embodiment of the present invention. [Figure 9] FIG. 9 shows a schematic perspective view of a support member in a hair-cutting unit according to a second practical embodiment of the present invention, the support member having three sets of guide grooves and a carrier part in which the guide grooves in the driven element are arranged. [Figure 10] FIG. 10 shows a schematic perspective view of the support member shown in FIG. 9, without the carrier portion. [Figure 11] FIG. 11 shows a schematic perspective view of an individual carrier part. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The invention will now be described in more detail with reference to the drawings, in which the same or similar parts are designated by the same reference numerals.

[0026] FIG. 1 shows a rotary electric shaver suitable for shaving beard hair as an example of a rotary electric shaver 1 according to an embodiment of the present invention. The rotary electric shaver 1 comprises a main body 2 and a shaving assembly 3, where the main body 2 is designed to allow a user of the shaver 1 to grip and manipulate the shaver 1, while the shaving assembly 3 is the part of the shaver 1 that is placed and moved on the skin to remove hair. In this example, the shaving assembly 3 comprises three hair-cutting units 4 supported on a base unit 5 of the shaving assembly 3. When the rotary electric shaver 1 is actually applied for the purpose of performing a shaving operation, the actual process of cutting the hair protruding from the skin is performed at the position of the hair-cutting units 4. In the context of the present invention, the number of hair-cutting units 4 can be freely selected and does not necessarily have to be three. The main body 2 may have the function of housing at least one electric motor for driving the components of each hair-cutting unit 4. The main body 2 may further comprise a means, such as a rechargeable battery, for supplying power to said at least one electric motor. The shaving assembly 3 and the main body 2 are usefully removably connectable to one another, as known per se in the field of rotary electric shavers.

[0027] Each hair-cutting unit 4 comprises a combination of an external cutting member 10 and an internal cutting member 20, as will be explained in more detail with reference to Fig. 2. The external cutting member 10 is of a generally cup-shaped design and is suitable for at least partially accommodating the internal cutting member 20 therein. The external cutting member 10 comprises an annular shaving track 11, the upper surface of which is a skin contact surface 12 intended to face and contact the skin to be subjected to a shaving action. The shaving track 11 comprises a number of lamellae 13 extending along the width of the shaving track 11 in a substantially radial direction relative to a central axis 14 of the hair-cutting unit 4, said central axis 14 coinciding with an axis of rotation 21 about which the internal cutting member 20 can rotate relative to the external cutting member 10. An opening present between the lamellae 13 constitutes a hair entry opening 15 of the shaving track 11. The side surfaces of the lamella 13 constitute a hair-cutting surface 16 suitable for cutting hair in cooperation with a hair-cutting edge 22 of a hair-cutting element 23 of the internal cutting member 20. The invention also relates to the case in which the shaving track 11 does not comprise a lamella 13 or does not only have a lamella 13, such as in the case in which the entire shaving track 11 is provided with a pattern of tooth-like elements and / or (circular) holes instead of or in addition to the lamella 13. The invention also relates to the case in which more than one shaving track 11 is present in the external cutting member 10.

[0028] When the internal cutting member 20 is actuated to rotate and a portion of skin is actually contacted by the external cutting member 10 at the location of the skin contact surface 12, a shaving action can be performed. Actuation of the internal cutting member 20 can be performed in a known manner by the drive mechanism of the rotary electric shaver 1. When the combination of the external cutting member 10 and the internal cutting member 20 is moved over the portion of skin while the internal cutting member 20 is actuated to rotate, hair protruding from the portion of skin becomes trapped in the hair entry opening 15 of the shaving track 11 of the external cutting member 10 and at that position is cut as a result of cooperation between the hair-cutting surface 16 of the shaving track 11 of the external cutting member 10 and the hair-cutting edge 22 of the hair-cutting element 23 of the rotating internal cutting member 20.

[0029] The external cutting member 10 includes a central portion 17 with a central bearing portion designed to be used for rotationally supporting the internal cutting member 20 within the hair-cutting unit 4 as well as the shaving track 11. The central portion 17 of the external cutting member 10 also serves to support a decorative cap 25 configured to cover a portion of the external surface of the external cutting member 10. In this example, the central portion 17 comprises a centrally located recess and the cap 25 comprises a protrusion received in the recess.

[0030] Each hair-cutting unit 4 further comprises a support member 30 having an upper surface 31 surrounding the external cutting member 10. According to the invention, each hair-cutting unit 4 has an exposed distance d 2 by which the skin-contacting surface 12 of the shaving track 11 projects relative to the upper surface 31 of the support member 30, as will be described below. e Based on the presence of the adjustment system in the hair-cutting unit 4, the user can adjust the exposure distance d according to personal preference. e , where it should be noted that these personal preferences may be different for different areas of skin to be shaved. Generally speaking, the adjustment system comprises an adjustment actuator which adjusts the exposure distance d via the mutual relative rotation of the external cutting member 10 and the support member 30 about the central axis 14. eand an adjustment transmission system that allows the adjustment of the external cutting member 10 and the support member 30. The adjustment transmission system comprises a conversion mechanism that converts the relative rotation of the external cutting member 10 and the support member 30 around the central axis 14 into a relative axial movement of the external cutting member 10 and the support member 30 in an axial direction A parallel to the central axis 14. In this example, the external cutting member 10 is rotatable over a limited angle and displaceable in the axial direction A within a limited range, while the support member 30 is a stationary component of the hair-cutting unit 4. Thus, in this example, the relative rotation of the external cutting member 10 and the support member 30 around the central axis 14 is realized by realizing the rotation of the external cutting member 10 around the central axis 14, while the relative movement of the external cutting member 10 and the support member 30 in the axial direction A is realized by realizing the movement of the external cutting member 10 in the axial direction A.

[0031] The conversion mechanism of the above-mentioned adjustment transmission system comprises at least one set of guide grooves 41 and driven elements 42, which set will be referred to as the adjustment set below. The general working principle of this type of conversion mechanism is explained based on figures 3 to 5. In figure 3 the external cutting member 10 is shown, which is partially depicted in a simplified form, in particular so that the hair inlet 15 of the shaving track 11 is not visible. For the sake of completeness, it should be noted that terms such as "upper", "top" and "bottom" used in this specification should be understood in relation to the assumption that the position of the shaving track 11 relative to the position of the internal cutting member 20 in the hair-cutting unit 4 is in a higher position in the axial direction A.

[0032] In particular, FIG. 3 shows that it is practical to have three adjustment sets, arranged at an angular interval of 120° around the central axis 14, with the guide grooves 41 being arranged on the inner surface 32 of the support member 30, while the driven elements 42 are arranged on the outer peripheral surface 18 of the external cutting member 10, but this does not change the fact that other options are also covered by the invention. In FIG. 3, two of the three driven elements 42 arranged on the external cutting member 10 are visible. Furthermore, in FIG. 3, a driven gear 51 is visible, which is attached to the external cutting member 10. As in the conversion mechanism, this driven gear 51 is part of the adjustment transmission system. It would be practical to integrate the driven elements 42 and the driven gear 51 in a single part 19, as shown in FIG. 3.

[0033] A particular feature of the guide groove 41 lies in the general fact that it is inclined with respect to an imaginary plane perpendicular to the central axis 14. As a result, when the external cutting member 10 is rotated around the central axis 14, the interaction between the guide groove 41 and the driven element 42 in each adjustment set causes the external cutting member 10 to be further raised or lowered in the axial direction A relative to the support member 30, depending on the direction in which the external cutting member 10 is rotated. In figures 4 and 5 the same part of a part of the hair-cutting unit 4 is shown for different rotational positions of the external cutting member 10 around the central axis 14. Starting from the situation shown in figure 4, the situation shown in figure 5 is obtained by rotating the external cutting member 10 around the central axis 14 through a limited angle. In this process, as is clear when comparing the figures with each other, the external cutting member 10 is lowered relative to the support member 30, as a result of which the value of the exposed distance de is reduced. From the situation shown in FIG. 5, the situation shown in FIG. 4 can be restored by rotating the external cutting member 10 about the central axis 14 through the same limited angle but in the opposite rotational direction.

[0034] Figures 6 to 8 relate to a hair-cutting unit 4 according to a first practical embodiment of the invention. In Figure 6, the support member 30 of the hair-cutting unit 4 is shown. In this figure, the guide groove 41 has an exposed distance d eIt can be seen that the guide groove 41 includes a stop device 43 for determining an initial position of the driven element 42 in the guide groove 41 corresponding to the minimum value of axial length 14 of the guide groove 41, the stop device 43 being at the lowest end in the axial direction A of the guide groove 41. It can also be seen that the stop device 43 of one guide groove 41 of the adjustment sets includes an elastic element in the form of a pretension spring 44. In FIG. 7, components of three hair-cutting units 4 are shown as part of a shaving assembly 3 having hair-cutting units 4. These components include an external cutting member 10 and a support member 30, in which case it should be noted that, as in FIG. 3, the external cutting member 10 is partially drawn in simplified form so that in particular the hair inlet 15 of the shaving track 11 is not visible. Also shown as an example of a component of the adjustment actuator is a drive gear 52 arranged centrally between the hair-cutting units 4, which drive gear 52 is able to realize the rotation of the external cutting member 10 around the corresponding central axis 14 of each hair-cutting unit 4. In this regard, it is noted that the drive gear 52 may be driven by an electric motor provided solely for that purpose. In such a case, if it is appropriate to change the direction in which the drive gear 52 is rotated, the electric motor may be controlled to reverse the direction of rotation of its output shaft, or a coupling that may be present between the output shaft of the electric motor and the drive gear 52 may be adjusted to reverse the manner in which rotation of the output shaft of the electric motor is transmitted to the drive gear 52. By providing a dedicated electric motor, the adjustment system may operate independently of the internal cutting member 20 and, if necessary, may adjust the exposure distance d during the shaving operation. e Therefore, it is possible to change the value of the exposure setting d e can be an adaptive shaving function. In practical cases where a high gear reduction ratio is used between the output shaft of the electric motor and the drive gear 52, it may be necessary to count the number of rotations of the output shaft to accurately achieve the desired exposure distance setting.

[0035] In Fig. 7 it can be seen that in each hair-cutting unit 4 the driven gears 51 have one gap 53 in each adjustment set, where there are no gear teeth. In Fig. 8 a perspective view of the assembly of the external cutting member 10 with the component 19 including the driven element 42 and the driven gears 51 is shown, in which the external cutting member 10 is partially depicted in simplified form, in particular in such a way that the hair inlet 15 of the shaving track 11 is not visible, as in Figs. 3 and 7. The gaps 53 are arranged in a specific manner, i.e. in such a way that when the driven element 42 is in the initial position in the guide groove 41 in each adjustment set, one gap 53 faces the driving gear 52, so that the driving gear 52 cannot drive the driven gear 51. Based on the presence of the gaps 53 in the driven gears 52 of each hair-cutting unit 4 it is possible to realize / guarantee the synchronization of the exposure distance settings of the multiple hair-cutting units 4. This is particularly relevant in situations where it is expected that the exposure distance settings of the hair-cutting units 4 may vary from one hair-cutting unit to another, which occurs in particular after the user has disassembled and subsequently assembled at least one of the hair-cutting units 4. The synchronization is performed by rotating the driving gear 52 counterclockwise as seen in the bottom view of FIG. 7. Assuming that the exposure distance settings are different for each of the hair-cutting units 4, what actually happens is that at a certain point in time, in one of the hair-cutting units 4, as a result of the rotation of the external cutting member 10 caused by the rotation of the driving gear 52 via the driven gear 51 attached to said external cutting member 10, said driven element 42 reaches its initial position in the guide channel 41 of the respective adjustment set of the corresponding hair-cutting unit 4, while this has not yet happened in the other two hair-cutting units 4. At this point in time, the continued rotation of the driving gear 52 no longer causes the rotation of the driven gear 51 of said one hair-cutting unit 4. This is because at this point, one of the gaps 53 of the driven gear 51 faces the driving gear 52 .As the driving gear 52 continues to move, the driven element 42 reaches its initial position in the guide channel 41 of each adjustment set, and the situation of the driven gear 51 and the driving gear 52 being separated is reached in the second of the hair-cutting units 4, and then in the third of the hair-cutting units 4. Thus, finally, an equal exposure distance setting is achieved in all the hair-cutting units 4 (in this example, the exposure distance is at its minimum value). It follows from the above that, due to the design of the driven gear 51 with the gap 53, this exposure distance setting is obtained at different times during the counterclockwise rotation of the driving gear 52 as seen from the bottom side.

[0036] Once the exposure distance settings among the multiple hair-cutting units 4 have been synchronized, the exposure distance d can be adjusted by rotating the drive gear 52 clockwise as viewed from the bottom side. e It is possible to set any other desired value of the driving element 42 of each hair-cutting unit 4. The fact is that, when in each hair-cutting unit 4 the driven element 42 is in its initial position in the guide groove 41, the pretension spring 44 acts to urge the driven element 42 of each adjustment set outward from its initial position in the guide groove 41. Thus, as soon as the driving gear 52 starts to rotate clockwise as viewed from the bottom side under the influence of the pretension spring 44, the driven gear 51 and the driving gear 52 of each hair-cutting unit 4 can be coupled again and the driven gear 51 of each hair-cutting unit 4 can be rotated until a suitable rotation position is obtained in view of the desired exposure distance setting of the external cutting member 10 around the central axis 14.

[0037] Considering the above description of how the exposure distance settings are synchronized between the different hair-cutting units 4, it will be practical to select a manner of controlling the shaving assembly 3 that includes rotating the drive gear 52 counterclockwise as viewed from the bottom side about the central axis 14 through an angle large enough to ensure that the minimum value of the exposure distance de is achieved in all of the hair-cutting units 4, and performing this step during an initial operating phase of the shaving assembly 3. This can be performed as a standard routine such that the desired synchronization of the exposure distance settings between the hair-cutting units 4 is always obtained, and the rotation angle can be selected to be 120° in the present case of three adjustment sets per hair-cutting unit 4. The exposure distance de at the minimum value of the desired exposure distance setting is selected to be 120° in the present case of three adjustment sets per hair-cutting unit 4. e If different, the desired exposure setting is then achieved by rotating drive gear 52 clockwise, as viewed from the bottom, through the appropriate angle about central axis 14 as previously described.

[0038] 4 and 5 in conjunction with the hair-cutting unit 4 according to the first practical embodiment of the present invention, it can be seen that the change from the situation shown in FIG. 4 to the situation shown in FIG. 5 involves a counterclockwise rotation of the drive gear 52 as seen from the bottom side. Such a rotation reduces the exposed distance d e The invention covers any way allowing the user to indicate what value of the exposure distance de should be set, such as by pressing an appropriate button or touching a touch screen which may be present on the body 2 of the rotary electric shaver 1 or on a cradle holding the shaver 1, or by using an app on a mobile device arranged to control the operation of the shaver 1.

[0039] Figures 9 to 11 relate to a hair-cutting unit 4 according to a second practical embodiment of the invention, which is designed to rely on features other than having at least one gap 53 in the driven gear 51. Firstly, as seen in Figure 9, it should be noted that in the hair-cutting unit 4 according to the second practical embodiment of the invention, the stop devices 43 of the guide grooves 41 are arranged in such a way that the maximum value of the exposed distance de is obtained when the driven element 42 is in its initial position in the guide groove 41. Secondly, it should be noted that the three adjusting sets of guide grooves 41 are provided in the carrier part 33 of the support member 30. In this example, the main part of the support member 30 is provided with a hook-like element 34 for fixing the axial position of the carrier part 33 in the main part of the support member 30. It can further be seen in Figure 10 that the main part of the support member 30 is provided with a corrugated annular surface 35 and in Figure 11 that the carrier part 33 is also provided with a corrugated annular surface 36 in a position for facing and engaging said corrugated annular surface 35 of the main part of the support member 30 when the carrier part 33 is in position within the support member 30. The presence of cooperating corrugated annular surfaces 35, 36 on the support member 30 in combination with the presence of stops 43 in the guide grooves 41 allows synchronisation of exposure distance settings between different hair-cutting units 4 sharing a drive gear 52, as will be explained below.

[0040] Assuming a position of the driven element 42 in the guide groove 41 in each adjustment set of the hair-cutting unit 4 different from its initial position and the normal rest position of the carrier part 33 in the main part of the support member 30, it can be seen that if the external cutting member 10 with the driven element 42 is rotated about the central axis 14 in a direction in which the driven element 42 finally abuts against the stop 43, i.e. in a direction in which it reaches its initial position in the guide groove 41, then if the rotation of the external cutting member 10 is continued at that point, the moment acting in the tangential direction about the central axis 14 at the position where the corrugated annular surfaces 35, 36 engage with each other between the main part of the support member 30 and the carrier part 33 will increase until the friction between these surfaces 35, 36 is overcome and the carrier part 33 will also rotate around the central axis 14, entrained by the external cutting member 10. Thus, the situation in which the driven element 42 is in its initial position in the guide groove 41 and the associated exposure value d e The maximum value of exposure distance d is maintained without any biasing force forcing the driven element 42 away from said position. In this way, based on the fact that the carrier part 33 can be rotated about the central axis 14 when the driven element 42 is in the initial position in the guide groove 41, it is possible to realize the synchronization of the exposure distance settings among the hair-cutting units 4 while using a common drive gear 52, for example as shown in Fig. 7 for the hair-cutting unit 4 according to the first practical embodiment of the present invention, for simultaneously driving all of the multiple external cutting members 10 of each hair-cutting unit 4. e Once the maximum value of exposure distance d is set and the carrier part 33 is set to move, the fact that the external cutting member 10 continues to rotate together with the external cutting members 10 of the other hair-cutting units 4 does not further affect the exposure distance setting. e The maximum value of is reached, at which point synchronization is completed. Then, the exposure distance d eIf it is necessary to set another value for exposure distance other than the maximum value, the direction of rotation of the external cutting members 10 can be reversed and they can be rotated in unison about their respective central axes 14 through the appropriate angle until the desired exposure distance setting is indeed achieved. When the direction of rotation of the external cutting members 10 is reversed and the driven element 42 leaves its initial position in the guide groove 41, the moment acting tangentially about the central axis 14 on the carrier part 33 is removed and therefore the carrier part 33 comes to rest again in the body part of the support member 30, since the corrugated annular surface 36 of the carrier part 33 and the corrugated annular surface 35 of the body part of the support member 30 engage with each other and are fixed to each other by friction.

[0041] It should be noted that with regard to the removable arrangement of the carrier part 33 in the main part of the support member 30, the correct function is obtained if the frictional moment required to realize the mutual relative rotation of the carrier part 33 and the main part of the support member 30 in the tangential direction about the central axis 14 is higher than the frictional moment required to realize the mutual relative rotation of the carrier part 33 and the component 19 attached to the external cutting member 10 and including the driven element 42 and the driven gear 51. This is therefore the determining factor for the choice regarding the material and the retention function between the carrier part 33 and the main part of the support member 30, in which case it should be noted that the alternative to using the combination of the illustrated corrugated annular surfaces 35, 36 between the carrier part 33 and the main part of the support member 30 is also possible in the context of the present invention.

[0042] Considering the above explanation of how the exposure distance settings according to the second practical embodiment of the present invention are synchronized between the different hair-cutting units 4, and with reference to what has been said in the above description with respect to the hair-cutting units 4 according to the first practical embodiment of the present invention, it is understood that the method for controlling a shaving assembly 3 having a plurality of hair-cutting units 4 according to the second practical embodiment of the present invention may be practical when selected to include a step aimed at enabling the driven element 42 in each adjustment set of each hair-cutting unit 4 to first reach its initial position in the guide groove 41, i.e. a step aimed at synchronizing the exposure distance settings between the plurality of hair-cutting units 4 during an initial operating phase of the shaving assembly 3.

[0043] When Figures 4 and 5 are viewed in conjunction with a hair-cutting unit 4 according to a second practical embodiment of the invention, it can be seen that the change from the situation shown in Figure 4 to the situation shown in Figure 5 involves a movement of the driven element 42 in the guide groove 41 away from its initial position in said guide groove 41. Such a movement results in an exposure distance d e This is a motion achieved by bottom-clockwise rotation of the external cutting member 10 about its central axis 14, which can be caused to rotate by bottom-counterclockwise rotation of the common central drive gear 52.

[0044] 6, 9 and 11, it is noted that, taking into account the possibility of disassembling and subsequent assembly of the hair-cutting unit 4 by a user, it is practical if the guide groove 41 is provided with an opening 45 through which the driven element 42 can be removed from the guide groove 41 by manually moving the external cutting member 10 and the support member 30 relative to one another in the axial direction A. In this regard, it is further noted that it is practical if the operation of the hair-cutting unit 4 is controlled in such a way that during the actual shaving operation the driven element 42 does not reach the position in the guide groove 41 where the opening 45 is present, or other measures are taken to prevent the driven element 42 from passing through the opening 45 during normal operation of the hair-cutting unit 4.

[0045] It will be apparent to those skilled in the art that the scope of the present invention is not limited to the above-described examples, and that several modifications and changes are possible without departing from the scope of the present invention defined in the appended claims. The present invention is to be construed as including all such modifications and changes insofar as they come within the scope of the claims or their equivalents. Although the present invention has been illustrated and described in detail in the drawings and the above description, such illustration and description should be considered as merely explanatory or exemplary, and not restrictive. The present invention is not limited to the disclosed embodiments. The drawings are schematic, and details not necessary for understanding the invention may be omitted, and are not necessarily drawn to scale.

[0046] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention from a study of the drawings, the description and the appended claims. In the claims, the word "comprising" does not exclude other steps or elements, and the singular does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope of the invention.

[0047] Elements and features described for or in connection with a particular embodiment can be combined with elements and features of other embodiments as appropriate, unless expressly stated otherwise. Thus, the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0048] As used herein, the terms "having" and "including" will be understood by those of skill in the art to also include the term "consisting of." Thus, the terms "having" or "including" may mean "consisting of" in some embodiments, but in other embodiments may mean "including / having / comprising at least what is defined and optionally one or more others."

[0049] Notable aspects of the present invention are summarized as follows: In a hair-cutting unit 4 for a rotary electric shaver 1 of the type comprising an external cutting member 10, an internal cutting member 20 and a support member 30, the exposed distance d of the skin-contacting surface 12 of the shaving track 11 of the external cutting member 10 protruding relative to the upper surface 31 of the support member 30 is e is adjustable. For this purpose, an adjustment system is provided, which in particular comprises at least one adjustment set of a guide groove 41 and a driven element 42 engaging in said guide groove 41, and also comprises an initial position setting system configured to enable synchronization of the exposure distance settings between the hair-cutting units 4, in which an initial position of the driven element 42 in the guide groove 41 defined by a stop device 43 of said guide groove 41 is realized and maintained. In particular, said synchronization comprises enabling the maintenance of said position of the driven element 42 in the guide groove 41 in at least one adjusted set of one hair-cutting unit 4, when said position has actually been reached as a result of relative mutual rotation of the external cutting member 10 and the support member 30 around the central axis 14 of the hair-cutting unit 4 in the appropriate rotational direction, while enabling the realization of a displacement of the driven element 42 towards said position in at least one adjusted set of other hair-cutting units 4, where the driven element 42 has not yet reached said position, as the relative mutual rotation of the external cutting member 10 and the support member 30 around the central axis 14 in the appropriate rotational direction continues.

Claims

1. A hair-cutting unit for a rotary electric shaver, comprising: an external cutting member having a shaving track with a hair entry opening; an internal cutting member surrounded by the external cutting member and rotatable relative to the external cutting member about a central axis of the hair-cutting unit; a support member surrounding and supporting the external cutting member; an adjustment system for adjusting an exposed distance of a skin contact surface of the shaving track protruding from an upper surface of the support member, the adjustment system comprising an adjustment actuator and an adjustment transmission system, through which the adjustment actuator is capable of adjusting the exposed distance via a relative rotation of the external cutting member and the support member about the central axis, the adjustment transmission system comprising a conversion mechanism for converting the relative rotation of the external cutting member and the support member about the central axis into a relative axial movement of the external cutting member and the support member in an axial direction parallel to the central axis; The conversion mechanism includes at least one set of guide grooves and a driven element that engages with the guide grooves, The guide groove is inclined with respect to a virtual plane perpendicular to the central axis, and is provided on one of i) an inner surface of the support member surrounding the external cutting member and ii) an outer circumferential surface of the external cutting member; the driven element is provided on the other of i) the inner surface of the support member and ii) the outer circumferential surface of the external cutting member; the guide groove has a stop device defining an initial position of the driven element in the guide groove corresponding to one of a minimum value and a maximum value of the exposed distance; the adjustment actuator is operable in a first operating state to realize a relative rotation of the external cutting member and the support member about the central axis in a first rotational direction, thereby obtaining a displacement of the driven element in a direction towards the initial position in the guide groove, while in a second operating state to realize a relative rotation of the external cutting member and the support member about the central axis in a second rotational direction opposite to the first rotational direction; the adjustment transmission system further comprising an initial position setting system for stopping the relative axial movement of the external cutting member and the support member during continued operation of the adjustment actuator in the first operating state when the driven element reaches the initial position in the guide groove, thereby maintaining one of the minimum and maximum values ​​of the exposure distance. Hair cutting unit.

2. The hair-cutting unit according to claim 1 , wherein the external cutting member is rotatable about the central axis relative to the support member.

3. the adjustment transmission system includes a driven gear attached to the external cutting member, while the adjustment actuator includes a drive gear engaging the driven gear; said first and second operating conditions of said adjustment actuator being accompanied by corresponding opposite first and second direction rotations of said drive gear; A hair-cutting unit according to claim 2.

4. 4. A hair-cutting unit according to claim 2 or 3, wherein the initial position setting system prevents the adjustment actuator from acting on the external cutting member during continued operation of the adjustment actuator in the first operating state when the driven element reaches the initial position in the guide groove.

5. the initial position setting system having a gap in the drive gear where no gear teeth are present for each set of the guide groove and the driven element; the gap is disposed relative to one of the guide groove and the driven element provided on the outer surface of the external cutting member such that when the driven element is in the initial position in the guide groove, the gap faces the driving gear and the driving gear cannot drive the driven gear; A hair-cutting unit according to claim 4 when dependent on claim 3.

6. 6. The hair-cutting unit according to claim 5, wherein a stop device in the guide groove in one of the at least one set of guide grooves and driven elements comprises an elastic element which urges the driven element out of its initial position in the guide groove when the driven element is in its initial position in the guide groove.

7. The guide groove is provided in a carrier portion of the support member, the initial positioning system allows rotation of the carrier part together with the external cutting member about the central axis relative to a main part of the support member during continued operation of the adjustment actuator in the first operating state when the driven element reaches the initial position in the guide groove. A hair-cutting unit according to claim 2 or 3.

8. 8. The hair-cutting unit according to claim 7, wherein the initial position setting system comprises a holding device which holds the carrier part in a stationary position in the main part of the support member when the driven element is in a position other than the initial position in the guide groove, while allowing the carrier part to rotate about the central axis relative to the main part of the support member when the adjustment actuator operates in the first operating state and the driven element reaches the initial position in the guide groove.

9. 9. A hair-cutting unit according to claim 8, wherein the holding device comprises friction structures on surfaces of the carrier part and / or the main part of the support member which contact each other and extend tangentially around the central axis.

10. 10. A hair-cutting unit according to any one of claims 1 to 9, wherein the guide groove has an opening through which the driven element can be removed from the guide groove by manually moving the external cutting member and the support member relative to each other in the axial direction.

11. 11. The hair-cutting unit according to claim 1, wherein the conversion mechanism has three sets of guide grooves and driven elements, the three sets being arranged at angular intervals of 120 degrees around the central axis.

12. A shaving assembly comprising at least two hair-cutting units according to any one of claims 1 to 11 and a base unit supporting said at least two hair-cutting units.

13. 13. The shaving assembly according to claim 12, wherein the adjustment actuator in each of the hair-cutting units is operated in the first operating state during an initial operating stage of the shaving assembly such that a driven element in the at least one set of guide grooves and driven elements in each of the hair-cutting units can reach the initial position in the guide groove.

14. 14. A shaving assembly according to claim 12 or 13, wherein the adjustment system of the hair-cutting units comprises a common adjustment actuator, the common adjustment actuator comprising a common drive gear centrally located between the hair-cutting units.

15. A rotary electric shaver comprising a main body and a shaving assembly according to any one of claims 12 to 14, the base unit of the shaving assembly being connected to the main body.

Images