Adjustable dorsal support for a seat

Abstract

The invention relates to a dorsal support (10) for a seat, comprising: - a structural panel (11), - at least two deformable lateral plates (12.1, 12.2) each having a movable end portion (13.1, 13.2) and a reference end portion (14.1, 14.2), - the movable end portion (13.1, 13.2) of each lateral plate (12.1, 12.2) being mechanically connected to a corresponding slide (15.1, 15.2, 15.3, 15.4), and - an actuating device (16) able to move the movable end portion (13.1, 13.2) along the slide (15.1, 15.2, 15.3, 15.4), such that each lateral plate (12.1, 12.2) is able to pass from a non-deformed state, in which each lateral plate (12.1, 12.2) extends substantially in one plane, to a deformed state, in which each lateral plate (12.1, 12.2) is deformed by buckling so as to have a curved shape ensuring lateral retention of a passenger's back, and vice versa.

Description

DESCRIPTION TITLE: ADJUSTABLE BACK SUPPORT FOR A SEAT

[0001] The present invention relates to an adjustable back support for a seat. The invention finds a particularly advantageous application in the field of aeronautics, in particular with seats intended to be installed in first class or business class aircraft cabins.

[0002] As is known per se, this type of seat offers the passenger different comfort positions, from a "sitting" position or TTL position (for "Taxi Take-Off Landing" according to English terminology) to a "bed" position, in which the seat defines a substantially horizontal sleeping surface for the passenger to lie down. Intermediate comfort positions are also offered, such as the "relax" position in which a seat back is strongly inclined. Generally, these intermediate positions are obtained by tilting the pivoting backrest around a horizontal axis and perpendicular to an extension axis of the seat.

[0003] Business class seats typically feature flat backrests to ensure an acceptable level of comfort when a passenger wishes to sleep on the seat in a lie-flat position during a long flight. On the other hand, the flat shape of the backrest can cause significant discomfort when seated, as the passenger's body will not be sufficiently supported laterally on the seat.

[0004] There are pneumatic back support systems for airplane seats that offer personalized comfort and ergonomic support. However, these systems add mechanical complexity to the seats as they require the integration of components such as valves, pumps, and air tanks to function properly. This type of system therefore increases the manufacturing, maintenance, and repair costs of the seats.

[0005] Despite regular maintenance to ensure their functionality, pneumatic systems can be subject to mechanical failures or air leaks during flight, significantly reducing passenger comfort and requiring repairs. Performance issues also arise in the long term due to wear and tear on valves and pumps. Furthermore, regarding user experience, some passengers do not appreciate the feel of air bags due to the noise associated with adjusting the air pressure.

[0006] The invention aims to effectively remedy the aforementioned drawbacks by proposing a back support for a seat comprising: - a structural panel, - at least two deformable side plates each having a movable end portion and a reference end portion, - at least two slides mounted on the structural panel, - the movable end portion of each side plate being mechanically linked to a corresponding slide, and - an actuating device capable of moving the movable end portion in the direction of the reference end portion along the slide, so that each side plate is capable of passing from an undeformed state in which each side plate extends substantially in a plane to a deformed state in which each side plate is deformed by buckling so as to have a curved shape ensuring lateral support for the back of a passenger, and vice versa.

[0007] The invention thus makes it possible to offer, particularly for business class seats, an adjustable back support improving the comfort of passengers when seated in their seat. The invention also has the advantage of being robust and low-noise compared to the use of pneumatic systems.

[0008] According to one embodiment of the invention, the side plates in the deformed state have, in a cross-sectional view, an inclination towards the inside of the structural panel.

[0009] According to one embodiment of the invention, at least one deformation stop is associated with each side plate, each deformation stop being fixed to the structural panel, so that when a side plate passes from an undeformed state to a deformed state, the side plate comes to bear against the deformation stop which initiates the deformation of the side plate along a preferred direction of deformation.

[0010] According to one embodiment of the invention, said back support further comprises a deformable central plate arranged between the side plates, said central plate comprising a movable end portion and a reference end portion, - the movable end portion of the central plate being mechanically linked to at least one corresponding slide, - the actuating device also being able to move the movable end portion of the central plate towards the reference end portion along the slide, so that the central plate is able to pass from an undeformed state in which the central plate extends substantially in a plane to a deformed state in which the central plate is deformed by buckling so as to have a curved shape providing lumbar support for the passenger, and vice versa.

[0011] According to one embodiment of the invention, said back support comprises two internal slides arranged on either side of the central plate, each internal slide comprising a carriage mechanically linked on the one hand to the movable end portion of the central plate and on the other hand to a movable end portion of a corresponding side plate, so as to allow simultaneous movement of the movable end portion of the central plate and the movable end portions of the side plates.

[0012] According to one embodiment of the invention, said back support further comprises two external slides arranged on either side of the "side plate-central plate-side plate" assembly, each external slide comprising a carriage to which a movable end portion of a corresponding side plate is connected.

[0013] According to one embodiment of the invention, each carriage is mechanically linked to a movable end portion of a corresponding side plate by means of a ball joint.

[0014] According to one embodiment of the invention, the side plates comprise openwork areas so as to control a curvature shape of the side plates in the deformed state.

[0015] According to one embodiment of the invention, the actuating device comprises an electric actuator.

[0016] According to one embodiment of the invention, the actuating device comprises a gripping element, such as a handle, intended to be grasped manually by a passenger.

[0017] The invention also relates to a seat for an aircraft comprising: - a seat, - a file and - a back support as previously defined.

[0018] According to one embodiment of the invention, the backrest being movable between a raised position and a lowered position, the seat is provided with a kinematic module allowing it to be movable between a "seated" position and a "bed" position in which the seat and the backrest in the lowered position define a substantially horizontal sleeping plane for the passenger, the back support being mechanically connected to an element of the kinematic module, so that a movement from the "bed" position to the "seated" position causes the side plates to move from an undeformed state to a deformed state.

[0019] According to one embodiment of the invention, said seat comprises a covering assembly covering the back support.

[0020] The present invention will be better understood and other characteristics and advantages will become apparent upon reading the detailed description which follows, including embodiments given for illustrative purposes with reference to the attached figures, presented as non-limiting examples, which may serve to complete the understanding of the present invention and the description of its implementation and, where appropriate, contribute to its definition, in which:

[0021] [Fig. 1a] [Fig. 1b] Figures 1a and 1b are perspective views of an adjustable back support according to the invention provided with side plates and a central plate respectively in the undeformed state and in the deformed state;

[0022] [Fig. 2a] [Fig. 2b] Figures 2a and 2b are cross-sectional views of an adjustable back support according to the invention provided with side plates and a central plate respectively in the undeformed state and in the deformed state;

[0023] [Fig. 3] Figure 3 is a perspective view of an adjustable back support according to the invention without the central plate and without a side plate;

[0024] [Fig. 4a] [Fig. 4b] Figures 4a and 4b are respectively exploded perspective and conventional perspective views of a slide carriage used with the adjustable back support according to the invention;

[0025] [Fig. 5] Figure 5 is a front view of an adjustable back support according to the invention provided with an electric actuator;

[0026] [Fig. 6] The figure is a front view of an adjustable back support according to the invention provided with a gripping means;

[0027] [Fig. 7] Figure 7 is a perspective view of an aircraft seat structure according to the invention comprising an adjustable back support according to the present invention;

[0028] [Fig. 8] Figure 8 is a front view of an alternative embodiment of an adjustable back support according to the invention with only two side plates;

[0029] [Fig. 9] Figure 9 is a front view of an alternative embodiment of an adjustable back support according to the invention consisting of a single-piece plate.

[0030] It should be noted that the structural and / or functional elements common to the different embodiments may have the same references. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0031] In the remainder of the description, the relative terms of the type "lower", "upper", "horizontal", "vertical" are understood by reference to the common meaning that a person observing the back support according to the invention installed on a seat in a seated position would give them.

[0032] Figures 1a and 1b show a back support 10 intended to be mounted on the front face of a seat back against which the back of a passenger is intended to rest.

[0033] The back support 10 comprises a structural panel 11. The structural panel 11 has a rectangular or square shape, or another shape. The structural panel 11 has a width substantially equal to a width of the backrest. The width of the structural panel is substantially equal to an overall width of the three deformable plates 12.1, 12.2, 20 described below. The structural panel 11 has a height covering a significant portion of the height of the backrest, in particular two-thirds or more.

[0034] The back support 10 comprises at least two deformable side plates 12.1, 12.2 each having a movable end portion 13.1, 13.2 and a reference end portion 14.1, 14.2 opposite the corresponding movable end portion 13.1, 13.2. As explained in more detail below, the movable end portions 13.1, 13.2 are movable in the direction of the reference end portions 14.1, 14.2 so as to deform by buckling the side plates 12.1, 12.2 then having a curved shape to ensure lateral support of the back of a passenger.

[0035] The side plates 12.1, 12.2 extend longitudinally along two opposite sides of the structural panel 11. The side plates 12.1, 12.2 have a trapezoidal shape but may alternatively have another shape, in particular a triangular shape (see figure 8).

[0036] A movable end portion 13.1, 13.2 and a reference end portion 14.1, 14.2 correspond to end edges of a side plate 12.1, 12.2 opposite each other forming a non-zero angle with each other.

[0037] A reference portion 14.1, 14.2 may be fixed in translation relative to the structural panel 11. Alternatively, a reference portion 14.1, 14.2 is movable towards the corresponding movable end portion 13.1, 13.2 in which case, the movable end portion 13.1, 13.2 and the reference end portion 14.1, 14.2 move towards each other.

[0038] Alternatively, the end portions 14.1, 14.2 are the movable end portions and the end portions 13.1, 13.2 are the fixed end portions. Thus, it is possible to provide either upper end portions 13.1, 13.2 movable towards the lower end portions 14.1, 14.2 fixed, or lower end portions 14.1, 14.2 movable towards the upper end portions 13.1, 13.2 fixed, or upper end portions 13.1, 13.2 and lower end portions 14.1, 14.2 movable towards each other.

[0039] The back support 10 further comprises a deformable central plate 20 arranged between the side plates 12.1, 12.2. The central plate 20 may have a rectangular or square shape or any other shape suitable for the application. The central plate 20 comprises a movable end portion 21 and a reference end portion 22. The movable end portion 21 and the reference end portion 22 correspond to two end edges of the central plate 20 opposite each other. As explained in more detail below, the movable end portion 21 is movable in the direction of the reference end portions 22 so as to deform by buckling the central plate 20 then having a curved shape to ensure lumbar support for the back of a passenger.

[0040] The reference end portion 22 may be fixed in translation relative to the structural panel 11. Alternatively, the reference end portion 22 may be movable in the direction of the movable end portion 21, in which case the movable end portion 21 and the reference end portion 22 move towards each other.

[0041] Alternatively, the end portion 22 is the movable end portion and the end portion 21 is the fixed end portion. Thus, it is possible to provide either an upper end portion 21 movable towards the fixed lower end portion 22, or a lower end portion 22 movable towards the fixed upper end portion 21, or an upper end portion 21 and a lower end portion 22 movable towards each other.

[0042] The side plates 12.1, 12.2 and the central plate 20 are preferably made of a thermoplastic material. Alternatively, the plates 12.1, 12.2, 20 may be made of a thermosetting material. The plates 12.1, 12.2, 20 can be made by plastic injection. Plates 12.1, 12.2, 20 may be reinforced by reinforcing elements, such as fibers, made of the same material as the plates or of different materials. Alternatively, the side plates 12.1, 12.2 are made of a metallic material, in particular steel or aluminum, a monolithic composite material with carbon fibers and / or fiberglass which may incorporate pivot lines to promote deformation, a material having superelasticity such as Nitinol (nickel-titanium alloy), or any other elastically deformable material suitable for the application.

[0043] Slides 15.1, 15.2, 15.3, 15.4 are mounted on the structural panel 11. The movable end portions 13.1, 13.2 of the side plates 12.1, 12.2 as well as the movable end portion 21 of the central plate 20 are mechanically connected to a corresponding slide 15.1, 15.2, 15.3, 15.4. The slides 15.1, 15.2, 15.3 and 15.4 here have a rectilinear shape but could alternatively have a curved shape in order to promote deformation of the side plates 12.1, 12.2 and / or of the central plate 20.

[0044] In this case, the back support 10 comprises two internal slides 15.1, 15.2 arranged on either side of the central plate 20. Each internal slide 15.1, 15.2 comprises a guide rail 25, in particular in the form of a rod, and a carriage 26 capable of sliding along the guide rail 25.

[0045] A carriage 26 of an inner slide 15.1 is mechanically connected on the one hand to the movable end portion 21 of the central plate 20 and on the other hand to a movable end portion 13.1, 13.2 of a corresponding side plate 12.1, 12.2, so as to allow simultaneous movement of the movable end portion 21 of the central plate 20 and the movable end portions 13.1, 13.2 of the side plates 12.1, 12.2. Each carriage 26 belonging to the inner slides 15.1, 15.2 is arranged near two adjacent corners of a side plate 12.1, 12.2 and of the central plate 20.

[0046] In addition, two external slides 15.3, 15.4 are arranged on either side of the "side plate 12.1 - central plate 20 - side plate 12.2" assembly. Each external slide 15.3, 15.4 comprises a carriage 26 to which a movable end portion 13.1; 13.2 of a corresponding side plate 12.1, 12.2 is connected.

[0047] Advantageously, in order to give freedom of movement to the side plates 12.1, 12.2, each carriage 26 is mechanically linked to a movable end portion 13.1, 13.2 of a corresponding side plate 12.1, 12.2 by means of a ball joint 27, as shown in FIGS. 4a and 4b. Each carriage 26 is made in two parts 26.1, 26.2 delimiting between them a housing intended to receive the ball joint 27 on which is fixed a movable end portion 13.1, 13.2 of a side plate 12.1, 12.2.

[0048] The carriage 26 also comprises a through opening 30 into which the guide rod 25 is inserted to allow the carriage 26 to slide along the guide rod 25.

[0049] The connection between the carriage 26 of an internal slide 15.1, 15.2 and the movable end portion 21 of the central plate 20 is ensured by means of a fixing rod 31 mechanically linked to the movable end portion 21 of the central plate 20 and having one end inserted inside an opening 32 made in the corresponding carriage 26. The fixing rod 31 can be arranged inside a housing defined by a fold of an upper end edge of the central plate 21.

[0050] An actuating device 16 is capable of simultaneously moving the movable end portions 13.1, 13.2 of the side plates 12.1, 12.2 in the direction of the reference end portion 14.1, 14.2 as well as the movable end portion 21 of the central plate 20 in the direction of the reference end portion 22 along the slides 15.1, 15.2, 15.3, 15.4.

[0051] Each side plate 12.1, 12.2 then passes from an undeformed state in which each side plate 12.1, 12.2 extends substantially in one plane (see Figures 1a and 2a) to a deformed state in which each side plate 12.1, 12.2 is deformed by buckling so as to present a curved shape ensuring lateral support for the back of a passenger (see figure 1 b and 2b). A stroke C (see figure 1 b) of the carriages 26 allowing the side plates to pass 12.1, 12.2 from an undeformed state to a deformed state is a few centimeters. The trolleys 26 may have intermediate stable positions so that the passenger can adjust the comfort of the backrest.

[0052] As seen in Figure 2b, when the side plates 12.1, 12.2 are in the deformed state, the side plates 12.1, 12.2 have, in a cross-sectional view, an inward inclination of the structural panel 11 so as to provide lateral support for the back of a passenger. By "inward inclination" is meant a side plate 12.1, 12.2 having an inclined face facing the center of the structural panel 11. Thus, in the cross-sectional view of Figure 2b, a height of a side plate 12.1, 12.2 measured relative to the structural panel 11 decreases when moving from the outside towards the center of the structural panel 11. Such a configuration makes it possible to prevent the passenger from slumping to the side of the seat. The two side plates 12.1, 12.2 in the deformed state can take a generally conical shape.

[0053] Furthermore, the central plate 20 passes from an undeformed state in which the central plate 20 extends substantially in a plane (see Figures 1a and 2a) in a deformed state in which the central plate 20 is deformed by buckling so as to have a curved shape providing lumbar support for the passenger (see Figure 1b and 2b). The central plate 20 advantageously has a gentle, flattened, non-cylindrical support curve to match the shape of the lumbar area of ​​a passenger's lower back.

[0054] When the side plates 12.1, 12.2 and the central plate 20 are in a deformed state, there is continuity of shape between the curvature of the outer face of the central plate 20 and the curvature of the outer face of the side plates 12.1, 12.2.

[0055] In the embodiment of Figure 5, the actuating device 16 comprises an electric actuator 35. The electric actuator 35 is connected to the carriages 26 and / or to the movable end portions 13.1, 13.2 of the side plates 12.1, 12.2 and / or to the movable end portion 21 of the central plate 20 by means of cables 37. The electric actuator 35 can take the form of an electric motor or a linear electric cylinder.

[0056] In the embodiment of Figure 6, the actuating device 16 comprises a gripping element 36, such as a handle, intended to be grasped manually by a passenger. The gripping element 36 is connected to the carriages 26 and / or to the movable end portions 13.1, 13.2 of the side plates 12.1, 12.2 and / or to the movable end portion 21 of the central plate 20 by means of cables 37.

[0057] At least one cable 37 can be connected to a drive carriage 34 arranged in the middle of an upper edge of the central plate 20. The drive carriage 34 is guided in translation relative to the structural panel 11 by means of a slide 38. The slide 38 comprises a tongue connected to the drive carriage 34 capable of moving along a guide groove of complementary shape made in the structural panel 11. Alternatively, the slides 15.1, 15.2, 15.3, 15.4 can have the same configuration as the slide 38 or any other form of slide adapted to the application. Alternatively, as described below, the back support 10 is controlled by the kinematics of the seat.

[0058] When the movable end portions 13.1, 13.2 of the side plates 12.1, 12.2 are moved in a direction away from the reference end portion 14.1, 14.2 and the movable end portion 21 of the center plate 20 is moved in a direction away from the reference end portion 22, the side plates 12.1, 12.2 as well as the center plate 20 change from the deformed state to the undeformed state.

[0059] At least one deformation stop 17 visible in Figure 3 is associated with each side plate 12.1, 12.2. Each deformation stop 17 is fixed on the structural panel 11, so that when a side plate 12.1, 12.2 passes from an undeformed state to a deformed state, the side plate 12.1, 12.2 bears against the deformation stop 17 which initiates the deformation of the side plate 12.1, 12.2 along a preferred direction of deformation. Deformation stops 17 may also be associated with the central plate 20 to initiate the deformation of the central plate 20 along a preferred direction of deformation. A deformation stop 17 may take the form of a cylindrical stud or any other form of protuberance or projection adapted to the application.

[0060] As illustrated in particular in Figures 1 a and 1 b, the side plates 12.1, 12.2 and / or the central plate 20 comprise openwork zones 33 so as to control a curvature shape of the side plates 12.1, 12.2 and of the central plate 20 in the deformed state. The openwork zones 33 are constituted by through openings. The openwork zones 33 preferably have an oblong shape. The addition of openwork zones 33 on the side plates 12.1, 12.2 and / or the central plate 20 makes it possible to obtain a non-linear curvature to achieve optimal passenger comfort.

[0061] Figure 7 shows a seat 40 convertible into a berth comprising a frame 39 on which are mounted a seat structure 41 and a backrest structure 42. The backrest structure 42 has a front face on which the back of a passenger can rest and a rear face opposite the front face.

[0062] A back support 10 is mounted on the front face of the backrest structure 42. The back support 10 can be attached and fixed to the structure of backrest 42. Alternatively, the back support 10 is integrated into the backrest structure 42. In this case, the structural panel 11 at least partly constitutes the backrest structure 42.

[0063] The seat 40 is provided with a kinematic module 43 allowing it to be movable between a "seated" position in which the seat structure 41 and the backrest structure 42 define a seated position for a passenger and a "bed" position in which the seat structure 41 and the backrest structure 42 define a substantially horizontal sleeping plane for the passenger.

[0064] For this purpose, the backrest structure 42 is movable in rotation around a horizontal axis X1 and perpendicular to an extension axis X of the seat 40 between a raised position and a lowered position in which the backrest structure 42 extends in the same plane as the seat structure 41 to form the sleeping surface.

[0065] The kinematic module 43 comprises one or more actuator(s) associated with elements for guiding the translation and / or rotation of the various mobile elements of the seat 40 ensuring a movement of the backrest structure 42 towards the rear and, where appropriate, of the seat structure 41 towards the front relative to the chassis 39. The kinematic module 43 can be arranged at least partly under the seat structure 41.

[0066] The back support 10 is mechanically connected to an element of the kinematic module 43, so that a movement of the seat 40 from the bed position to the sitting position causes the side plates 12.1, 12.2 and / or the central plate 20 to move from an undeformed state to a deformed state. Thus, the seat 40 in the sitting position offers good back support to the passenger due to the deformation of the side plates 12.1, 12.2 while the seat 40 in the bed position offers good comfort to the passenger due to the flat configuration of the sleeping surface. In this case, the element of the kinematic module 43 to which the back support 10 is connected constitutes the actuating device.

[0067] The seat 40 may include a covering assembly 46 covering the back support 10. The covering assembly 46 includes one or more cushion(s) comfort cushion(s) made for example of foam and a cover arranged around the comfort cushion(s). The back support 10 is arranged under the covering assembly 46. The shape of the cushion(s) is modified during the deformation of the side plates 12.1, 12.2 and the central plate 20 so as to optimally support the back of a passenger.

[0068] A simplified version of the back support 10 consists of retaining only the trapezoidal-shaped plates 12.1 and 12.2. In this case, two embodiments are possible. According to a first embodiment, only the inner slides 15.1 and 15.2 are retained. According to a second embodiment, the inner slides 15.1 and 15.2 are removed by fixing the corresponding lateral edges of the plates 12.1, 12.2 to the structural panel 11, the mobility of at least one end portion of the plates 12.1, 12.2 being ensured by the outer slides 15.3 and 15.4 to ensure deformation of the plates 12.1, 12.2.

[0069] Figure 8 shows an alternative embodiment of the back support 10 according to the invention comprising only two side plates 12.1, 12.2 and two corresponding slides 15.3, 15.4. The side plates 12.1, 12.2 have a triangular shape. The side plates 12.1, 12.2 are mechanically connected to the structural panel 11 on the side of the corners located in a central part of the structural panel 11 by means of a ball joint 47. Such a back support 10 does not have a central plate 20.

[0070] In the preceding embodiments, the side plates 12.1, 12.2 and the central plate 20 constitute plates distinct from each other. Alternatively, in the embodiment of FIG. 9, the three plates 12.1, 12.2, 20 of the back support 10 form a single single-piece plate 49. In this case, the slides 15.1, 15.2, 15.3, 15.4 remain connected to the single-piece plate 49 as previously described. The single-piece plate 49 has a thickness and cutouts 50 allowing the plate 49 to deform. Certain cutouts 50 may be provided at the location of junction zones between two adjacent plates.

[0071] In the embodiments of Figures 1a, 1b, 5, 6 and 7, the side plates 12.1, 12.2 and the central plate 20 are each constituted by a single-piece type plate. Alternatively, the side plates 12.1, 12.2 and / or the central plate 20 are made in several parts articulated together, for example by means of hinges, pivot connections, ball joints, folding grooves, so as to facilitate the deformation of the plates 12.1, 12.2, 20.

[0072] Alternatively, it may be considered to replace the cable system which allows the carriages of the slides 15.1, 15.2; 15.3, 15.4 to be moved by endless screws. These endless screws can be controlled by an electromechanical actuator of the motor type associated with a reducer.

[0073] The invention can also be implemented with seats of other means of transport, such as for example seats installed in motor vehicles, trains or boats etc.

[0074] Of course, the various features, variations and / or embodiments of the present invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

[0075] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms and other variants that may be envisaged by those skilled in the art within the scope of the present invention and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

Claims

CLAIMS 1. Back support (10) for a seat characterized in that it comprises: - a structural panel (11), - at least two deformable side plates (12.1, 12.2) each having a movable end portion (13.1, 13.2) and a reference end portion (14.1, 14.2), - at least two slides (15.1, 15.2, 15.3, 15.4) mounted on the structural panel (11), - the movable end portion (13.1, 13.2) of each side plate (12.1, 12.2) being mechanically linked to a corresponding slide (15.1, 15.2, 15.3, 15.4), and - an actuating device (16, 43) capable of moving the movable end portion (13.1, 13.2) in the direction of the reference end portion (14.1, 14.2) along the slide (15.1, 15.2, 15.3, 15.4), such that each side plate (12.1, 12.2) is capable of passing from an undeformed state in which each side plate (12.1, 12.2) extends substantially in one plane to a deformed state in which each side plate (12.1, 12.2) is deformed by buckling so as to have a curved shape ensuring lateral support for the back of a passenger, and vice versa, - the side plates (12.1, 12.2) in the deformed state having, in a cross-sectional view, an inclination towards the inside of the structural panel (11).

2. Back support according to claim 1, characterized in that at least one deformation stop (17) is associated with each side plate (12.1, 12.2), each deformation stop (17) being fixed on the structural panel (11), so that when a side plate (12.1, 12.2) passes from an undeformed state to a deformed state, the side plate (12.1, 12.2) comes to bear against the deformation stop (17) which initiates the deformation of the side plate (12.1, 12.2) along a preferred direction of deformation.

3. Back support according to claim 1 or 2, characterized in that it further comprises a deformable central plate (20) arranged between the side plates (12.1, 12.2), said central plate (20) comprising a movable end portion (21) and a reference end portion (22), - the movable end portion (21) of the central plate (20) being mechanically linked to at least one corresponding slide (15.1, 15.2), - the actuating device (16) also being able to move the movable end portion (21) of the central plate (20) towards the reference end portion (22) along the slide (15.1, 15.2), so that the central plate (20) is able to pass from an undeformed state in which the central plate (20) extends substantially in a plane to a deformed state in which the central plate (20) is deformed by buckling so as to have a curved shape providing lumbar support for the passenger, and vice versa.

4. Back support according to claim 3, characterized in that it comprises two internal slides (15.1, 15.2) arranged on either side of the central plate (20), each internal slide (15.1, 15.2) comprising a carriage (26) mechanically linked on the one hand to the movable end portion (21) of the central plate (20) and on the other hand to a movable end portion (13.1, 13.2) of a corresponding side plate (12.1, 12.2), so as to allow simultaneous movement of the movable end portion (21) of the central plate (20) and the movable end portions (13.1, 13.2) of the side plates (12.1, 12.2).

5. Back support according to claim 4, characterized in that it further comprises two external slides (15.3, 15.4) arranged on either side of the "side plate (12.1)-central plate (20)-side plate (12.2)" assembly, each external slide (15.3, 15.4) comprising a carriage (26) to which a movable end portion (13.1, 13.2) of a corresponding side plate (12.1, 12.2) is connected.

6. Back support according to claim 4 or 5, characterized in that each carriage (26) is mechanically linked to a movable end portion (13.1, 13.2) of a corresponding side plate (12.1, 12.2) by means of a ball joint (27).

7. Back support according to any one of claims 1 to 6, characterized in that the side plates (12.1, 12.2) comprise openwork zones (33) so as to control a curvature shape of the side plates (12.1, 12.2) in the deformed state.

8. Back support according to any one of claims 1 to 7, characterized in that the actuating device (16) comprises an electric actuator (35).

9. Back support according to any one of claims 1 to 7, characterized in that the actuating device (16) comprises a gripping element (36), such as a handle, intended to be grasped manually by a passenger.

10. Seat (40) for an aircraft characterized in that it comprises: - a seat (41), - a file (42) and - a back support (10) defined according to any one of the preceding claims.

11. Seat according to claim 10, characterized in that the backrest (42) being movable between a raised position and a lowered position, the seat (40) is provided with a kinematic module (43) allowing it to be movable between a "seated" position and a "bed" position in which the seat (41) and the backrest (42) in the lowered position define a substantially horizontal sleeping plane for the passenger, - the back support (10) being mechanically connected to an element of the kinematic module (43), so that a movement from the "bed" position to the "sitting" position causes the side plates (12.1, 12.2) to move from an undeformed state to a deformed state.

12. Seat according to claim 10 or 11, characterized in that it comprises a covering assembly (46) covering the back support (10).

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