Seat component and seat, particularly of a motor vehicle

Abstract

The invention relates to a seat element (16) comprising at least one mattress (18) and a cover arranged around at least one mattress; the seat element comprising a first capacitive sensor (36) with coplanar interdigitated electrodes and a second capacitive sensor (38) with coplanar interdigitated electrodes arranged on the first side (32) of the seat element; the second capacitive sensor (38) being separated from the first capacitive sensor (36) along the longitudinal direction by a first distance (D1) of between 250 millimeters and 290 millimeters. Figure to be published with the abstract: Figure 2

Description

Title of the invention: Seat element and seat, in particular for a motor vehicle Technical field of the invention

[0001] The present invention relates to a seat element and a seat comprising this seat element. State of the prior art

[0002] Some people adopt an inappropriate sitting position on a seat or chair such as an office chair, a medical chair or a vehicle seat. This inappropriate posture can cause them back pain.

[0003] In particular, drivers often tend to slouch in their seats or hunch over due to fatigue or loss of muscle tone during long car journeys. Some drivers perform spinal twisting movements while driving with one hand or turning towards their neighbor.

[0004] These postures are not ergonomic and can cause lower back pain. Some cars may have a seat with a bad posture detection function.

[0005] For cars that are not equipped with this function, a removable seat cushion with this function can be mounted on the seat. This removable cushion must not only be suitable for people of different body shapes but also suitable for seats of different dimensions. In particular, in the field of motor vehicles, it would be desirable for the removable cushion to be suitable for category A, category B or category C seats.

[0006] For cars that are equipped with this function, it is desirable to provide a seat element, such as a seat back, capable of detecting poor postures of seat occupants, and in particular so-called rounded back postures, regardless of the morphology of the occupant. Presentation of the invention

[0007] A first aim of the present invention is to propose a seat element, such as a removable cushion, capable of detecting the poor postures of seat occupants having different morphologies and regardless of the size of the seat on which it is mounted.

[0008] A second object of the present invention is to propose a seat element, such as a seat back, capable of detecting the so-called rounded back postures of seat occupants having different morphologies and regardless of the size of the seat. Summary of the invention

[0009] The present invention relates to a seat element, in particular a seat element of a motor vehicle, the seat element comprising at least one mattress and a covering arranged around the at least one mattress; the seat element extending in a longitudinal direction and a transverse direction, the seat element comprising two transverse edges, a longitudinal central plane extending between and midway between the two lateral longitudinal edges, a first side of the seat element being located on one side of the longitudinal central plane, a second side being located on the other side of the longitudinal central plane; the seat element further comprising a first capacitive sensor with coplanar interdigital electrodes and a second capacitive sensor with coplanar interdigital electrodes arranged on the first side of the seat element; the second capacitive sensor being distant from the first capacitive sensor in the longitudinal direction by a first distance of between 250 millimeters and 290 millimeters, and preferably by a first distance equal to 270 millimeters. Advantageously, when the first and second capacitive sensors are separated by this distance, the capacitance values ​​that these sensors generate make it possible to detect a rounding of the back of the occupant of the seat around a horizontal axis regardless of the size of the seat and the morphology of the occupant of the seat.

[0010] The features set out in the following paragraphs may optionally be implemented. They may be implemented independently of one another or in combination with one another: - the seat element comprises a removable seat cushion intended to be placed on a seat; the seat comprising a seat and a backrest articulated to the seat, the backrest having a front face suitable for receiving the back of an occupant; the removable cushion being intended to be placed on the front face of the backrest of the seat. - the seat element is intended to be mounted on a seat comprising a headrest and at least one rod fixed to the backrest and to the headrest; the seat element comprising at least one opening intended to receive the at least one rod for fixing the headrest, the seat element having a front edge bordering the opening and extending on the front face of the seat backrest, and in which the first capacitive sensor is located at a second distance of between 200 millimeters and 300 millimeters, and preferably at a second distance of 250 millimeters from said front edge. - the seat comprises an upper face, and the seat element comprises a support portion intended to bear against the upper face of the seat, the support portion comprising a front end intended to be arranged between the upper face and the front face of the backrest and in which the first capacitive sensor is located at a second distance of between 200 and 300 millimeters, and preferably at a second distance of 250 millimeters from the front end of said support portion. - It comprises at least a third capacitive sensor with coplanar interdigitated electrodes arranged on the second side of the longitudinal central plane; the third capacitive sensor being distant from the second capacitive sensor in a longitudinal direction by a third distance of between 30 millimeters and 50 millimeters and preferably by a third distance equal to 40 millimeters. Advantageously, when the second and third capacitive sensors are separated by this third distance, the capacitance values ​​they generate make it possible to detect the torsion positions of the body regardless of the size of the seat and the morphology of the occupant. - the second capacitive sensor is separated from the third capacitive sensor by a fifth distance of between 50 millimeters and 150 millimeters; this fifth distance being measured in a transverse direction Y. - It further comprises a fourth capacitive sensor with coplanar interdigitated electrodes arranged on the mattress on the second side of the longitudinal central plane; the fourth capacitive sensor being distant from the first capacitive sensor in the longitudinal direction by a sixth distance of between 30 millimeters and 50 millimeters, and preferably by a sixth distance equal to 40 millimeters. - the fourth capacitive sensor is distant from the first capacitive sensor by a seventh distance of between 50 millimeters and 150 millimeters; this seventh distance being measured in a transverse direction. - at least one capacitive sensor extends in a transverse direction. - the seat element is intended to be articulated to a seat, the seat element forming a back of a seat, and in which the seat element comprises a supporting structure, the mattress being carried by the supporting structure, the covering being arranged around the mattress and the supporting structure, the first capacitive sensor and the second capacitive sensor being arranged between the mattress and the covering. - It comprises at least a third capacitive sensor with coplanar interdigitated electrodes arranged on the second side of the longitudinal central plane; the third capacitive sensor being distant from the second capacitive sensor in a longitudinal direction by a third distance of between 30 millimeters and 50 millimeters and preferably by a third distance equal to 40 millimeters. -It further comprises a fourth capacitive sensor with coplanar interdigitated electrodes arranged on the second side of the longitudinal central plane; the fourth capacitive sensor being distant from the first capacitive sensor in the longitudinal direction by a sixth distance of between 30 millimeters and 50 millimeters, and preferably by a sixth distance equal to 40 millimeters. - the seat element has an upper face, and in which the first capacitive sensor is located at a second distance of between 200 millimeters and 300 millimeters meters, and preferably at a second distance of 250 millimeters from said upper face. The invention also relates to a seat, in particular a motor vehicle seat, said seat comprising a seat and a backrest articulated to the seat, the backrest having a front face, a rear face and an upper face; the seat comprising a seat element according to the characteristics mentioned above, and in which the first capacitive sensor is located at a second distance of between 200 millimeters and 300 millimeters, and preferably at a second distance of 250 millimeters from the edge located between the upper face and the front face, when the seat element is fixed to the seat. Brief description of the figures

[0011] [Fig-1] is a perspective view of a seat on which a seat element rests according to a first embodiment;

[0012] [Fig.2] is a schematic sectional view of the seat element illustrated in [Fig.l], the section being taken in a median plane of the seat element;

[0013] [Fig.3] is a schematic front view of an example of a capacitive sensor intended to be arranged in a seat element according to the invention;

[0014] [Fig.4] is a schematic sectional view of a seat element according to a first variant of the seat element according to the first embodiment; and

[0015] [Fig.5] is a perspective view of a seat on which a second variant rests of the seat element according to the first embodiment; and

[0016] [Fig.6] is a perspective view of a seat comprising a seat and a seating element. seat according to a second embodiment. Detailed description of the invention

[0017] In the following description, the spatial positioning indications such as front, rear, top, bottom, upper, lower, horizontal, vertical etc. are to be interpreted as a function of the usual position of use of a seat, the usual position of a removable cushion arranged on the back of a seat as well as the position of a motor vehicle considered when it is moving forward. These usual positions are illustrated in [Fig.l]. In particular, the front face of a back is the face on which the occupant of the seat rests.

[0018] [Fig. 1] shows an example of a seat 2 according to the present invention. The seat 2 comprises a seat 4, a backrest 6 articulated to the seat and a headrest 12 fixed to the backrest by rods 14.

[0019] The backrest 6 further comprises a front face 8, a rear face 9, two lateral edges 10, a lower face 11 articulated to the seat and an upper face 13 opposite the lower face.

[0020] A seat element according to a first embodiment of the invention is intended to be placed on the front face 8 of the seat back. In this embodiment, this seat element is a removable cushion 16. This removable cushion 16 comprises at least one mattress 18 and a covering 19 surrounding the mattress. The mattress 18 comprises a layer of foam or padding. The mattress may also comprise several layers of foam or padding.

[0021] With reference to [Fig. 2], the removable cushion 16 extends in a longitudinal direction X and in a transverse direction Y perpendicular to the longitudinal direction X. The removable cushion 16 comprises two transverse edges 20, 22 extending in the transverse direction Y and two lateral longitudinal edges 24, 26 extending in the longitudinal direction X.

[0022] In the embodiment shown in Figures 1 and 2, the removable cushion 16 further comprises two openings 28 or notches intended to receive the rods 14 of the headrest. The openings have a front edge 30 located on the side of the front face 8 of the backrest, and a rear edge 31 located on the side of the rear face of the backrest, when the removable cushion 16 is mounted on the backrest of the seat.

[0023] For the purposes of this description, a longitudinal central plane (X,Z) is defined perpendicular to the median plane of the cushion. It intersects the center of the cushion along a central straight line XL. The central straight line XI is parallel to the lateral longitudinal edges 24, 26. The central straight line XI is located in the center, that is to say midway between the two lateral longitudinal edges 24, 26. For the purposes of this description, the side of the cushion located on one side of the longitudinal central plane (X,Z) for example on the right is called "first side 32" of the cushion, and the side of the cushion located on the other side of the longitudinal central plane for example on the left is called "second side 34".

[0024] [Fig. 2] schematically represents an example of a sectional view of the removable cushion 16 according to a first embodiment of the invention.

[0025] The removable cushion 16 comprises a first capacitive sensor 36 with coplanar interdigital electrodes and a second capacitive sensor 38 with coplanar interdigital electrodes, hereinafter called first and second capacitive sensors.

[0026] The first capacitive sensor 36 and the second capacitive sensor 38 are arranged between the covering 19 and the mattress when the mattress comprises a layer of foam. Alternatively, the first capacitive sensor 36 and the second capacitive sensor 38 are arranged between two layers of foam when the mattress comprises two layers of foam. The first capacitive sensor and the second capacitive sensor extend in the transverse direction Y. They are suitable for measuring capacitance values.

[0027] The first capacitive sensor 36 and the second capacitive sensor 38 are arranged on the first side 32 of the longitudinal central plane (X, Z). Preferably, the first capacitive sensor and the second capacitive sensor are aligned with each other along a first straight line X2 directed along the longitudinal direction X. The second capacitive sensor 38 is distant from the first capacitive sensor 36 along the longitudinal direction X by a first distance D1. The first distance D1 is between 250 millimeters and 290 millimeters. Preferably, the first distance D1 is equal to 270 millimeters.

[0028] The middle of the capacitive sensors is used to carry out the distance measurements along the longitudinal direction X in the present application as visible in [Fig.2],

[0029] When the first and second capacitive sensors are separated by this first distance, the capacitance values ​​generated by these sensors make it possible to detect a rounding of the back of the occupant of the seat around a horizontal axis regardless of the size of the seat and the morphology of the occupant of the seat. Morphology means the general shape of people. It includes the height and width of a person.

[0030] Advantageously, this positioning of the second capacitive sensor 38 makes it possible to detect a movement or a more pronounced pressure of a part of the pelvis of an occupant of the seat.

[0031] The first capacitive sensor 36 is located at a second distance D2 of between 200 millimeters and 300 millimeters from the front edge 30 of the opening 28 of the mattress. Preferably, the second distance is equal to 250 millimeters. This positioning of the first capacitive sensor 36 makes it possible to detect a movement or a more pronounced pressure of the shoulder blade of an occupant of the seat.

[0032] Preferably, the removable cushion 16 comprises a third capacitive sensor 40 with coplanar interdigital electrodes arranged between the covering 19 and the mattress or between two layers of foam of the mattress. The third capacitive sensor 40 is located on the second side 34 of the longitudinal central plane (X, Z). The third capacitive sensor 40 is spaced from the second capacitive sensor 38 in a longitudinal direction X, by a third distance D3 of between 30 millimeters and 50 millimeters. Preferably, the third distance D3 is equal to 40 millimeters. Here, the third capacitive sensor 40 is closer to the lower transverse edge 22 of the cushion than the second capacitive sensor 38. Advantageously, when the second capacitive sensor 38 and the third capacitive sensor 40 are separated by this third distance, the capacitance values ​​that they generate make it possible to detect the torsion positions of the body regardless of the size of the seat and the morphology of the occupant. A "torsion position" is a pivoting of the body around a vertical axis located at the level of the spine and any resulting poor posture of the pelvis. Such torsion can, for example, result from the fact that a driver holds the steering wheel with only one hand or that a person sitting on an office chair crosses one leg over the other. The relative offset of the third capacitive sensor 40 with respect to the second capacitive sensor 38 allows very effective detection of poor posture, when the removable cushion is arranged on seat backs of different dimensions and for people with different body shapes.

[0033] Preferably, the third capacitive sensor 40 is distant from the first capacitive sensor 36 in a longitudinal direction X by a fourth distance D4 of between 250 millimeters and 350 millimeters.

[0034] Preferably, the third capacitive sensor 40 is distant from the second capacitive sensor in the transverse direction Y by a fifth distance D5 of between 50 millimeters and 150 millimeters. The ends of the capacitive sensors on the side of the center of the cushion are used to carry out the measurements in the longitudinal direction Y, as visible in [Fig.2].

[0035] Preferably, the removable cushion 16 further comprises a fourth capacitive sensor 42 arranged between the covering 19 and the mattress or between two layers of foam of the mattress. The fourth capacitive sensor 42 is arranged on the second side 34 of the longitudinal central plane (X, Z). Preferably, the fourth capacitive sensor 42 is aligned with the third capacitive sensor 40 along a second straight line X3 directed in the longitudinal direction X of the cushion.

[0036] In the embodiment shown, the fourth capacitive sensor 42 is spaced from the first capacitive sensor 36 in the longitudinal direction X by a sixth distance D6 of between 30 millimeters and 50 millimeters. Preferably, the sixth distance D6 is equal to 40 millimeters. The fourth capacitive sensor 42 is distant from the third capacitive sensor 40 in the longitudinal direction X by the first distance DI. The fourth capacitive sensor 42 is here closer to the lower transverse edge 22 than the third capacitive sensor 40.

[0037] Preferably, the fourth capacitive sensor 42 is distant from the first capacitive sensor 36 by a seventh distance D7, this seventh distance D7 being measured in a transverse direction Y. The seventh distance D7 is between 100 millimeters and 200 millimeters.

[0038] Preferably, the four capacitive sensors are identical. An example of a capacitive sensor 36, suitable for being arranged in the cushion, has been shown in [Fig. 3].

[0039] The capacitive sensor 36 comprises a first electrode 44 and a second electrode 46 similar to the first electrode. Each electrode comprises a rod and fingers secured to the rod. The fingers extend perpendicular to the rod. The fingers are spaced apart from each other in a comb-like configuration. The second electrode is positioned relative to the first electrode such that the fingers of the second electrode are interposed between the fingers of the first electrode. An example of dimensions of the rods, fingers and spacings between the rods and fingers of a capacitive sensor that can be arranged in the removable pad is described in the patent application published under number FR 3 126 776.

[0040] The first electrode 44 is connected to a voltage source via an electrical connection wire 48. The voltage source generates a voltage of, for example, 5 volts. The second electrode 46 is connected to a ground via an electrical connection wire 48.

[0041] The first capacitive sensor 36, the second capacitive sensor 38, the third capacitive sensor 40, the fourth capacitive sensor 42 and the electrical connection wires 48 are arranged on a flexible support 50. The flexible support 50 is fixed against a layer of foam or padding of the mattress.

[0042] The removable cushion 16 may include a controller 52. The controller 52 may be disposed in a bag formed at one end of the cushion. The first electrode and the second electrode of the capacitive sensors 36, 38, 40, 42 are connected to the controller 52 via the electrical connection wires 48.

[0043] The controller is configured to periodically receive capacitance values ​​from the capacitive sensors. The controller is configured to detect a rotation of a body part, in particular a trunk part, of an occupant of the seat leaning against the seat cushion from the received capacitance values.

[0044] The controller 52 may be a programmable device that uses software or a specific integrated circuit (ASIC). The controller comprises a memory and executable code for implementing a method for detecting a rotation of a portion of the trunk of a seat occupant from the capacitance values ​​received from the capacitive sensors previously described. The memory comprises a random access memory, denoted RAM, and a read only memory denoted ROM. The memory may comprise executable code for implementing a method for detecting a rotation of a portion of the trunk of a seat occupant as described in the patent application published on August 26, 2022 in the name of the applicant under the number FR 3120124, as well as several ranges of variation of capacitance values ​​as described in this patent application. Ranges of variation of capacitance values ​​may be predefined during a learning phase.

[0045] The removable cushion 16 may comprise comfort equipment 54 arranged in the cushion between the covering 19 and the mattress or between two layers of foam of the mattress. The comfort equipment 54 comprises, for example, vibrating equipment or pneumatic equipment for performing a massage function, a ventilation actuator and heating equipment.

[0046] The comfort equipment 54 is connected to the controller 52. The controller 52 controls the operation of comfort equipment on command from the seat occupant or when it detects poor positioning of the seat occupant.

[0047] Eight comfort features 54 have been shown in [Fig.2]. Alternatively, the removable cushion comprises a different number of comfort features.

[0048] Alternatively, the removable cushion 16 does not include a controller. The electrical connection wires 48 are connected to a connector for connecting to a seat electrical wire harness.

[0049] According to a first variant illustrated in [Fig.4], the removable cushion 16 only comprises the first capacitive sensor 36 and the second capacitive sensor 38. The first capacitive sensor 36 and the second capacitive sensor 38 are separated by the first distance DI in the longitudinal direction X. Alternatively, the removable cushion is suitable for covering both the front face 8 of the backrest and the horizontal seat face of the seat base. When the removable cushion 16 is suitable for covering the backrest and the seat base, the capacitive sensors are arranged only on the part of the cushion intended to bear against the backrest of the seat.

[0050] [Fig. 5] shows a removable cushion 56 according to a second alternative embodiment of the first embodiment. The removable cushion 56 is arranged on the backrest 6 of the seat 2. The removable cushion 56 according to this second alternative embodiment is identical or similar to the removable cushion 16 according to the first embodiment except that the removable cushion 56 does not have openings 28 or notches. It is placed on the upper face 13 of the seat. It is fixed to the backrest for example by fastening cords.

[0051] The removable cushion 56 comprises a mattress 58 and a covering 19 arranged around the mattress. The removable cushion 56 comprises a support portion 60 intended to bear against the upper face 13 of the seat. This support portion 60 has the shape of a transverse strip of the mattress. The support portion 60 comprises a front end 62 intended to be arranged between the upper face 13 and the front face 8 of the backrest. In this variant, the first capacitive sensor 36 is located at a second distance D2 of between 200 millimeters and 300 millimeters from the front end 62 of the support portion 60. Preferably, the second distance D2 is located 250 millimeters from the front end 62 of the support portion 60.

[0052] The other technical elements of the removable cushion 56 according to this second variant are identical to the technical elements of the removable cushion 16 according to the first embodiment and will not be described again. For reasons of simplification, only the first capacitive sensor has been shown in [Fig. 5]. It is understood that the removable cushion 56 comprises two, three, or four capacitive sensors.

[0053] [Fig.6] represents a seat element according to a second embodiment. This seat element is constituted by a seat back 64. The seat back 64 is articulated to a seat 66. The back and the seat form a seat 68, in particular, a seat of a motor vehicle. The seat back 64 comprises a supporting structure not shown in [Fig. 6], a mattress 69 carried by the supporting structure and a covering 70 surrounding the mattress. The mattress 69 is constituted by a layer of foam carried by the supporting structure. The mattress 69 is the foam layer of the seat back. The covering 70 is the outer covering of the seat.

[0054] The first capacitive sensor 36 and the second capacitive sensor 38 are arranged between the mattress 69 and the covering 70; that is to say between the foam layer of the seat and the outer covering of the seat. The seat back 64 extends in a longitudinal direction X and a transverse direction Y. The seat back 64 comprises a lateral longitudinal edge 73 and a lateral longitudinal edge 75.

[0055] For the purposes of this description, a longitudinal central plane (X6, Z6) is defined perpendicular to the median plane of the seat back 64. It intersects the middle of the seat back in the longitudinal direction Y. The middle of the back in the longitudinal direction Y is defined by half the width of the back. The width of the back is measured between the two lateral longitudinal edges 73, 75. The longitudinal central plane (X6, Z6) extends between and midway between the two lateral longitudinal edges 73, 75. For the purposes of this description, the side of the seat back located on one side of the longitudinal central plane (X6, Z6) for example on the right is called "first side 72" of the back, and the side of the back located on the other side of the longitudinal central plane for example on the left is called "second side 74".

[0056] The seat back 64 comprises a first capacitive sensor 36 with coplanar interdigital electrodes and a second capacitive sensor 38 with coplanar interdigital electrodes, hereinafter called first and second capacitive sensors.

[0057] The first capacitive sensor and the second capacitive sensor are arranged between the foam layer of the seat back forming the mattress 69 and the covering 70. The first capacitive sensor and the second capacitive sensor extend in the transverse direction Y. They are suitable for measuring capacitance values. The first capacitive sensor 36 and the second capacitive sensor 38 are arranged on the first side 72 of the longitudinal central plane (X6, Z6).

[0058] The second capacitive sensor 38 is spaced from the first capacitive sensor 36 in the longitudinal direction X by a first distance DI. The first distance DI is between 250 millimeters and 290 millimeters. Preferably, the first distance DI is equal to 270 millimeters.

[0059] Preferably, the first capacitive sensor and the second capacitive sensor are aligned with each other along a straight line directed in the longitudinal direction X2.

[0060] Preferably, the first capacitive sensor 36 is located at a second distance D2 between 200 millimeters and 300 millimeters from the upper face 76 of the seat back. Preferably the second distance is equal to 250 millimeters.

[0061] Preferably, the seat back 64 comprises a third capacitive sensor 40 with coplanar interdigital electrodes arranged between the foam layer of the seat back forming the mattress 69 and the covering 70. The third capacitive sensor 40 is located on the second side 74 of the longitudinal central plane (X6, Z6). Preferably, the third capacitive sensor 40 is distant from the second capacitive sensor 38 in a longitudinal direction X, by a third distance D3 of between 30 millimeters and 50 millimeters. Preferably, the third distance D3 is equal to 40 millimeters. In the embodiment shown, the third capacitive sensor 40 is closer to the lower face 78 of the seat back than the second capacitive sensor 38. Preferably, the third capacitive sensor 40 is spaced in the transverse direction Y from the second capacitive sensor 38 by a fifth distance D5 of between 50 millimeters and 150 millimeters.

[0062] Preferably, the seat back 64 further comprises a fourth capacitive sensor 42 arranged between the foam layer forming the mattress 69 and the covering 70. The fourth capacitive sensor 42 is arranged on the second side 74 of the longitudinal central plane (X6, Z6). Preferably, the fourth capacitive sensor 42 is aligned with the third capacitive sensor 40 along a straight line X3 directed in the longitudinal direction X.

[0063] Preferably, the fourth capacitive sensor 42 is distant from the first capacitive sensor 36 in the longitudinal direction X by a sixth distance D6 of between 30 millimeters and 50 millimeters. Preferably, the sixth distance D6 is equal to 40 millimeters. Preferably, the fourth capacitive sensor 42 is distant from the third capacitive sensor 40 in the longitudinal direction X by the first distance DI. In the embodiment shown, the fourth capacitive sensor 42 is closer to the lower face 78 than the second capacitive sensor 38.

[0064] Preferably, the fourth capacitive sensor 42 is distant from the first capacitive sensor 36 by a seventh distance D7, this seventh distance D7 being measured in a transverse direction Y. The seventh distance D7 is between 100 millimeters and 200 millimeters.

Claims

Claims

1. Seat element (16, 56; 64) in particular a seat element of a motor vehicle, the seat element (16, 56; 64) comprising at least one mattress (18, 58; 69) and a covering (19; 70) arranged around the at least one mattress; the seat element extending in a longitudinal direction (X) and a transverse direction (Y), the seat element comprising two transverse edges (20, 22; 73, 75), a longitudinal central plane ((X, Z); (X6, Y6)) extending between and midway between the two lateral longitudinal edges, a first side (32; 72) of the seat element being located on one side of the longitudinal central plane, a second side (34; 74) being located on the other side of the longitudinal central plane; the seat element further comprising a first capacitive sensor (36) with coplanar interdigital electrodes and a second capacitive sensor (38) with coplanar interdigital electrodes arranged on the first side (32; 72) of the seat element;the second capacitive sensor (38) being distant from the first capacitive sensor (36) in the longitudinal direction by a first distance (Dl) of between 250 millimeters and 290 millimeters, and preferably by a first distance equal to 270 millimeters;

2. A seat element (16, 56) according to claim 1, wherein the seat element (16, 56) comprises a removable seat cushion intended to be placed on a seat; the seat (2) comprising a seat (4) and a backrest (6) articulated to the seat, the backrest (6) having a front face (8) suitable for receiving the back of an occupant; the removable cushion being intended to be placed on the front face (8) of the backrest of the seat (2).

3. A seat element (16) according to claim 2, wherein the seat element is intended to be mounted on a seat (2) comprising a headrest (12) and at least one rod (14) fixed to the backrest and to the headrest; and wherein the seat element comprises at least one opening (28) intended to receive the at least one rod (14) for fixing the headrest, the seat element having a front edge (30) bordering the opening (28) and extending over the front face (8) of the seatback, and wherein the first capacitive sensor (36) is located at a second distance (D2) of between 200 millimeters and 300 millimeters, and preferably at a second distance (D2) of 250 millimeters from said front edge (30).

4. A seat element (56) according to claim 2, wherein the seat (2) comprises an upper face (13), and in which the seat element comprises a support portion (60) intended to bear against the upper face (13) of the seat, the support portion (60) comprising a front end (62) intended to be arranged between the upper face (13) and the front face (8) of the backrest, and in which the first capacitive sensor (36) is located at a second distance (D2) of between 200 and 300 millimeters, and preferably at a second distance (D2) of 250 millimeters from the front end (42) of said support portion.

5. Seat element (16, 56) according to any one of claims 1 to 4, which comprises at least one third capacitive sensor (40) with coplanar interdigitated electrodes arranged on the second side (34) of the longitudinal central plane (X,Z); the third capacitive sensor (40) being distant from the second capacitive sensor (38) in a longitudinal direction (X) by a third distance (D3) of between 30 millimeters and 50 millimeters and preferably by a third distance (D3) equal to 40 millimeters.

6. Seat element (16, 56) according to claim 5, in which the second capacitive sensor (38) is distant from the third capacitive sensor (40) by a fifth distance (D5) of between 50 millimeters and 150 millimeters; this fifth distance (D5) being measured in a transverse direction (Y).

7. Seat element (16, 56) according to any one of claims 1 to 6, which further comprises a fourth capacitive sensor (42) with coplanar interdigitated electrodes arranged on the mattress (18, 58) on the second side (34) of the longitudinal central plane (X,Z); the fourth capacitive sensor (42) being distant from the first capacitive sensor (36) in the longitudinal direction (X) by a sixth distance (D6) of between 30 millimeters and 50 millimeters, and preferably by a sixth distance (D6) equal to 40 millimeters.

8. Seat element (16, 56) according to claim 7, in which the fourth capacitive sensor (42) is distant from the first capacitive sensor (36) by a seventh distance (D7) of between 50 millimeters and 150 millimeters; this seventh distance (D7) being measured in a transverse direction (Y)

9. A seat element (64) according to claim 1, wherein the seat element (64) is intended to be articulated to a seat (66), the seat element forming a back of a seat (64), and wherein the seat element comprises a supporting structure, the mattress (69) being carried by the supporting structure, the covering (70) being arranged around the mattress and the supporting structure, the first capacitive sensor (36) and the second capacitive sensor (38) being arranged between the mattress and the covering.

10. Seat element (64) according to claim 9, which comprises at least one third capacitive sensor (40) with coplanar interdigitated electrodes arranged on the second side (74) of the longitudinal central plane (X6, Z6); the third capacitive sensor (40) being distant from the second capacitive sensor (38) in a longitudinal direction (X) by a third distance (D3) of between 30 millimeters and 50 millimeters and preferably by a third distance (D3) equal to 40 millimeters.

11. Seat element (64) according to any one of claims 9 and 10, which further comprises a fourth capacitive sensor (42) with coplanar interdigitated electrodes arranged on the second side (74) of the longitudinal central plane (X6, Z6); the fourth capacitive sensor (42) being distant from the first capacitive sensor (36) in the longitudinal direction (X) by a sixth distance (D6) of between 30 millimeters and 50 millimeters, and preferably by a sixth distance (D6) equal to 40 millimeters.

12. A seat element (64) according to any one of claims 9 to 11, wherein the seat element comprises an upper face (76), and wherein the first capacitive sensor (36) is located at a second distance (D2) of between 200 millimeters and 300 millimeters, and preferably at a second distance (D2) of 250 millimeters from said upper face (76).

13. Seat (2) in particular a motor vehicle seat, said seat (2) comprising a seat (4) and a backrest (6) articulated to the seat, the backrest (6) having a front face (8), a rear face (9) and an upper face (13); the seat comprising a seat element (16, 56) according to any one of claims 1 to 8, and in which the first capacitive sensor (36) is located at a second distance (D2) of between 200 millimeters and 300 millimeters, and preferably at a second distance (D2) of 250 millimeters from the edge located between the upper face (13) and the front face (8), when the seat element is fixed to the seat.

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