Seat occupant height detection system and file

Abstract

The invention relates to a seat backrest, the backrest extending along a longitudinal direction (Z) and a transverse direction (Y); the backrest comprising: - at least a first and a second capacitive sensors with coplanar interdigitated electrodes arranged on a first zone (16) of the backrest located above a horizontal central plane (X,Y) and to one side of a vertical central plane (X,Z); the second capacitive sensor of the first zone being located above the first capacitive sensor of the first zone; the second capacitive sensor of the first zone being advanced a first distance relative to the first capacitive sensor of the first zone in the direction of the vertical central plane (X,Z). Figure to be published with the abstract: Figure 1

Description

Title of the invention: Backrest and device for detecting the size of an occupant of a seat Technical field of the invention

[0001] The invention relates to a backrest, in particular a motor vehicle backrest. The invention also relates to a device for detecting the size of an occupant of a seat. State of the prior art

[0002] The deployment of the front and side airbags of the front passenger side airbag as well as the seat belt pretensioning system can cause injuries to small passengers such as children. It is therefore desirable to develop devices for detecting the size of the occupant of a motor vehicle seat. Presentation of the invention

[0003] An object of the present invention is to provide a device for detecting the size of an occupant of a seat and a backrest comprising such a device. Summary of the invention

[0004] The present invention relates to a seat back, in particular a motor vehicle seat back, the back extending in a longitudinal direction and a transverse direction; - at least one first and one second capacitive sensor with coplanar interdigital electrodes called first and second first-zone capacitive sensors, said first-zone capacitive sensors being arranged on a first zone of the backrest located above a horizontal central plane and on one side of a vertical central plane; the second first zone capacitive sensor being located above the first first zone capacitive sensor; the second first zone capacitive sensor being advanced a first distance relative to the first first zone capacitive sensor towards the vertical central plane.

[0005] 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 first distance measured in the transverse direction is equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters. - It comprises at least a third capacitive sensor with coplanar interdigitated electrodes called the third first-zone capacitive sensor; said third sensor first zone capacitive sensor being arranged on the first zone of the backrest; the third first zone capacitive sensor being located above the second first zone capacitive sensor; the third first-zone capacitive sensor being advanced by a second distance relative to the second first-zone capacitive sensor in the direction of the vertical central plane; the second distance measured in the transverse direction being in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters. - It comprises at least a fourth capacitive sensor with coplanar interdigital electrodes called the fourth first-zone capacitive sensor; said fourth first-zone capacitive sensor being arranged on the first zone of the backrest; the fourth first-zone capacitive sensor being located above the third first-zone capacitive sensor; the fourth first-zone capacitive sensor being advanced by a third distance relative to the third first-zone capacitive sensor in the direction of the vertical central plane; the third distance measured in the transverse direction being in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters. - two first-zone capacitive sensors, arranged next to each other in the longitudinal direction, are separated from each other by a distance of between 5 millimeters and 20 millimeters. - It further comprises at least a first and a second capacitive sensors of second zone; said first and second capacitive sensors of second zone being arranged on a second zone of the backrest; said second zone being located above the horizontal central plane and on the other side of the vertical central plane; the second second zone capacitive sensor being located above the first second zone capacitive sensor; the second capacitive sensor of second zone being advanced by a fourth distance relative to the first capacitive sensor of second zone in the direction of the vertical central plane; the fourth distance measured in the transverse direction being in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters. -It comprises at least one third capacitive sensor with coplanar interdigitated electrodes called third second-zone capacitive sensor, said third second-zone capacitive sensor being arranged on the second zone of the backrest; the third second-zone capacitive sensor being located above the second second-zone capacitive sensor; the third capacitive sensor of the second zone being advanced by a fifth distance relative to the second capacitive sensor of second zone in the direction of the vertical central plane; the fifth distance being measured in the transverse direction; the fifth distance being in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters. - It comprises at least a fourth capacitive sensor with coplanar interdigital electrodes called the fourth second-zone capacitive sensor, said fourth second-zone capacitive sensor being arranged on the second zone of the backrest; the fourth second-zone capacitive sensor being located above the third second-zone capacitive sensor; the fourth capacitive sensor of the second zone being advanced by a sixth distance relative to the third capacitive sensor; the sixth distance, measured in the transverse direction; is in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters. - At least two first-zone capacitive sensors and two second-zone capacitive sensors are arranged symmetrically with respect to each other, with respect to the central vertical plane. - It further comprises electrical connection wires each connected to a first zone capacitive sensor and / or a second zone capacitive sensor; and a flexible support carrying the capacitive sensors and the electrical connection wires; a portion of the flexible support being arranged on an upper edge of the backrest, next to the headrest. - At least one capacitive sensor with coplanar interdigital electrodes comprises a first electrode and a second electrode, the first electrode and the second electrode each comprising a rod extending in a main direction, and branches integral with the rod, the branches extending in a secondary direction, the secondary direction being perpendicular to the main direction; the branches of the first electrode being separated from each other by the same interval, the branches of the first electrode being interposed between the branches of the second electrode, the rod and the branches of at least one electrode among the first electrode and the second electrode, having a dimension in the main direction of between 250 micrometers and 1,000 micrometers, and preferably, of between 500 micrometers and 800 micrometers. - The branches of at least one electrode among the first electrode and the second electrode have a dimension in the secondary direction of between 3 millimeters and 20 millimeters, and preferably of between 3 and 7 millimeters. - The branches of the first electrode have free ends, and in which a free end of a branch of the first electrode is spaced from a portion of the rod of the second electrode arranged opposite the latter, by a spacing of between 250 micrometers and 1000 micrometers, and preferably between 500 micrometers and 800 micrometers.

[0006] The invention also relates to a device for detecting the size of an occupant of a seat, in particular of a motor vehicle seat, the detection device comprising: - at least one flexible support having a strip shape having two lateral edges, the flexible support extending in a longitudinal direction; - at least one first and one second capacitive sensor with coplanar interdigitated electrodes called first and second capacitive sensors, and - electrical connection wires connected to the first and second capacitive sensors and extending in the longitudinal direction; the first and second capacitive sensors extending perpendicular to the longitudinal direction; the second capacitive sensor being advanced a first distance relative to the first capacitive sensor towards a lateral edge; the first distance, measured in a transverse direction, being equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters. Brief description of the figures

[0007] [Fig-1] is a diagram showing a seat having a backrest according to the invention;

[0008] [Fig.2] is a front view of a portion of the backrest illustrated in [Fig.l];

[0009] [Fig.3] is a front view of a capacitive sensor with coplanar interdigital electrodes arranged on the seat illustrated in [Fig.l]. Detailed description of the invention

[0010] In the following description, the spatial positioning indications such as top, bottom, upper, lower, horizontal, vertical etc. are to be interpreted according to the usual position of use of the seat.

[0011] The seat is defined relative to an orthogonal reference frame shown in [Fig.l]. Longitudinal direction X means a horizontal direction extending between the front and the rear of the vehicle seat. Transverse direction Y means a horizontal direction extending from one side of the vehicle seat to the other side of the seat. Vertical direction Z means the direction perpendicular to the longitudinal X and transverse Y directions.

[0012] [Fig. 1] represents an example of a seat 2 comprising a seat 4 and a backrest 6 connected to the seat, for example by an articulation system. This seat 2 is in particular intended for a vehicle, and in particular, for a motor vehicle.

[0013] The backrest comprises a headrest 7 fixed against an upper edge of the backrest. The backrest 6 comprises a backrest frame, a foam layer covering the backrest frame and a seat cover covering the foam layer. The backrest 6 extends in a transverse direction Y and a longitudinal direction Z. To facilitate understanding of the invention, a horizontal central plane (X, Y) and a vertical central plane (X, Z) are defined. The horizontal central plane (X, Y) extends horizontally. It passes substantially through the middle of the backrest in the longitudinal direction Z. The middle of the backrest in the longitudinal direction Z is defined by half the length of the backrest. The length of the backrest is measured between an upper edge 8 and a lower edge 10 of the backrest. The vertical central plane (X, Z) extends vertically. It passes substantially through the middle of the backrest in the transverse direction Y. The middle of the backrest in the transverse direction Y is defined by half the width of the backrest. The width of the backrest is measured between a lateral edge 12 and the opposite lateral edge 14 of the backrest.

[0014] With reference to [Fig.l], the seat backrest comprises a first zone 16 and a second zone 18. The first zone 16 is an upper lateral zone located on one side of the vertical central plane (X, Z), for example on the right side. The second zone 18 is an upper lateral zone located on the other side of the vertical central plane (X, Z), for example on the left side. The first and second zones are located above the horizontal central plane (X, Y). In the example illustrated in Figures 1 and 2, and in no way limiting, the first zone 16 of the backrest comprises a first flexible support 20, four capacitive sensors 22, 24, 26, 28 with coplanar interdigitated electrodes, hereinafter called “first zone capacitive sensors”, and electrical connection wires 27, 29.

[0015] The capacitive sensors 22, 24, 26, 28 and the electrical connection wires 27, 29 are supported by the first flexible support 20.

[0016] The electrical connection wires 27, 29 are connected to an electrical connector not shown.

[0017] The first flexible support 20 has a strip shape having two lateral edges 23, 25. The first flexible support 20 is placed in abutment against the foam layer. It extends vertically against the backrest. A part of the first flexible support rests on the upper edge 8 of the backrest on one side of the headrest 7.

[0018] Preferably, the four capacitive sensors 22, 24, 26, 28 of the first zone are identical. They are described in detail below in connection with [Fig. 3].

[0019] For example, a first capacitive sensor 22 of first zone is arranged at a first interval II of the intersection of the vertical central plane (X, Z) and the plane formed by the surface of the seat. For example, the first interval II has a length of between 4 and 6 centimeters.

[0020] A first and a second capacitive sensor are arranged perpendicular to at least one lateral edge 23, 25. The second capacitive sensor 24 of the first zone is located above the first capacitive sensor 22 of the first zone. The second sensor capacitive sensor 24 of first zone is advanced by a first distance DI relative to the first capacitive sensor 22 of first zone in the direction of the vertical central plane (X, Z). In this description, the term "advanced" means "having been offset", "having been translated", "having been moved" relative to the first capacitive sensor 22 of first zone in the transverse direction Y and in the direction of the vertical central plane (X, Z). In other words, the second capacitive sensor 24 of first zone is closer to the vertical central plane (X, Z) by a spacing having a length equal to the first distance Dl. The first distance DI is measured in the transverse direction Y. The first distance Dl is equal to or greater than 5 millimeters, preferably it is equal to or greater than 10 millimeters.

[0021] The first capacitive sensor 22 of the first zone is distant from the second capacitive sensor 24 of the first zone by a distance E in the longitudinal direction Z. The distance E is between 5 millimeters and 20 millimeters.

[0022] Similarly, a third first-zone capacitive sensor 26 is arranged on the first zone 16 of the backrest. The third first-zone capacitive sensor 26 is located above the second first-zone capacitive sensor 24. The third first-zone capacitive sensor 26 is advanced by a second distance D2 relative to the second first-zone capacitive sensor 24 in the direction of the vertical central plane (X, Z). The second distance is measured along the transverse direction Y. The second distance D2 is equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

[0023] The second capacitive sensor 24 of the first zone is distant from the third capacitive sensor 26 of the first zone by the distance E in the longitudinal direction Z. In the embodiment shown, the distance E between the second capacitive sensor 24 and the third capacitive sensor 26 is identical to the distance between the first capacitive sensor 22 and the second capacitive sensor 24. According to a variant not shown, these distances have different lengths.

[0024] Finally, in the same way, a fourth capacitive sensor 28 of first zone is located above the third capacitive sensor 26 of first zone. The fourth capacitive sensor 28 of first zone is advanced by a third distance D3 relative to the third capacitive sensor 26 of first zone in the direction of the vertical central plane (X, Z). The third distance D3 is measured in the transverse direction Y. The third distance D3 is equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

[0025] The third capacitive sensor 26 of the first zone is distant from the fourth capacitive sensor 28 of the first zone by the distance E in the longitudinal direction Z. In the embodiment shown, the distance E between the third capacitive sensor 26 and the fourth capacitive sensor 28 is identical to the distance between the first capacitive sensor 22 and the second capacitive sensor 24. According to a variant not shown, these gaps have different lengths.

[0026] In the example illustrated in Figures 1 and 2, and in no way limiting, the second zone 18 of the backrest comprises a second flexible support 30, four capacitive sensors 32, 34, 36, 38 with coplanar interdigitated electrodes, hereinafter called “second zone capacitive sensors”, and electrical connection wires 37, 39.

[0027] The capacitive sensors 32, 34, 36, 38 and the electrical connection wires 37, 39 are supported by the second flexible support 30. The second flexible support 30 is placed in abutment against the foam layer. It is arranged on the upper edge 8 of the backrest on one side of the headrest 7 opposite the side supporting the first flexible support 30.

[0028] In the same way as the first zone 16, the second zone 18 comprises a first capacitive sensor 32 of second zone, arranged at a second interval 12 from the intersection of the vertical central plane (X, Z) and the plane formed by the surface of the seat. For example, the second interval 12 has a length of between 4 and 6 centimeters.

[0029] In the example illustrated in Figures 1 and 2, the second interval 12 has the same length as the first interval II. According to a variant not shown, the second interval 12 has a length different from the first interval II.

[0030] A second capacitive sensor 34 of second zone is located above the first capacitive sensor 32 of second zone. The second capacitive sensor 34 of second zone is advanced relative to the first capacitive sensor 32 of second zone in the direction of the vertical central plane (X, Z). The term "advanced" means "having been offset", "having been translated", "having been moved" relative to the first capacitive sensor 32 in the transverse direction Y and in the direction of the vertical central plane (X, Z). In other words, the second capacitive sensor 34 of second zone is closer to the vertical central plane (X, Z) by a spacing having a length equal to the fourth distance D4. The fourth distance D4 is measured in the transverse direction Y. The fourth distance D4 is equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

[0031] The second capacitive sensor 32 of the second zone is distant from the second capacitive sensor 34 of the second zone by a distance E in the longitudinal direction Z. The distance E is between 5 millimeters and 20 millimeters. In the embodiment shown as an example, the gap between the first capacitive sensor 32 of the second zone and the capacitive sensor 34 of the second zone is identical to the gap between the first capacitive sensor 22 of the first zone and the capacitive sensor 34 of the first zone. Alternatively, the gap between the first capacitive sensor 32 of the second zone and the capacitive sensor 34 of the second zone, and the gap between the first capacitive sensor 22 of first zone and the capacitive sensor 34 of first zone have different lengths.

[0032] A third second-zone capacitive sensor 36 is arranged on the second zone 18. The third second-zone capacitive sensor 36 is located above the second second-zone capacitive sensor 24. The third second-zone capacitive sensor 36 is advanced by a fifth distance D5 relative to the second second-zone capacitive sensor 34 in the direction of the vertical central plane (X, Z). The fifth distance D5 is measured along the transverse direction Y. The fifth distance D5 is equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

[0033] The second capacitive sensor 34 of the second zone is distant from the third capacitive sensor 36 of the second zone by the gap E in the longitudinal direction Z. In the embodiment shown, the gap E between the second capacitive sensor 34 and the third capacitive sensor 36 is identical to the gap between the first capacitive sensor 32 and the second capacitive sensor 34. According to a variant not shown, these gaps have different lengths.

[0034] Finally, a fourth second-zone capacitive sensor 38 is located above the third second-zone capacitive sensor 36. The fourth second-zone capacitive sensor 38 is advanced by a sixth distance D6 relative to the third second-zone capacitive sensor 36 in the direction of the vertical central plane (X, Z). The sixth distance D6 is measured along the transverse direction Y. The sixth distance D6 is equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

[0035] In the embodiment illustrated in Figures 1 and 2, the first distance DI is equal to the second and third distances. Alternatively, the first distance D1 is different from the second distance D2 and the third distance D3.

[0036] Alternatively, the second distance D2 is different from the third distance D3.

[0037] Similarly, in the embodiment illustrated in Figures 1 and 2, the fourth distance D4 is equal to the fifth distance D5 and the sixth distance D6. Alternatively, the third distance D3 is different from the fifth distance D5 and the sixth distance D6.

[0038] Alternatively, the fifth distance D5 is different from the sixth distance D6.

[0039] According to a first variant, the first zone 16 comprises two or three first zone capacitive sensors offset from each other in the transverse direction Y. According to a second variant, the first zone 16 and / or the second zone 18 comprises five to eight first zone capacitive sensors, all offset from each other in the transverse direction Y.

[0040] Alternatively, only one zone among the first and second zones comprises capacitive sensors.

[0041] [Fig. 3] represents an example of a capacitive sensor 22 with coplanar interdigitated electrodes arranged on the seat according to the invention. This capacitive sensor will not be described in full. In particular, all of these dimensional characteristics will not be described in full. Only these particular characteristics will be described. As regards its other characteristics, they are described in the patent application published under number FR 3126776 in the name of the applicant.

[0042] The capacitive sensor 22 with coplanar interdigitated electrodes comprises a first electrode 40 and a second electrode 42.

[0043] The first electrode 40 and the second electrode 42 each comprise a rod 44, and branches 46 secured to the rod. The branches 46 extend perpendicular to the rod 44. The branches 46 of the first electrode are separated from each other by the same interval IN. The branches 46 of the first electrode are interposed between the branches 46 of the second electrode.

[0044] The rod 44 of at least one electrode among the first electrode 40 and the second electrode 42, has a dimension ed along a main direction PI of between 250 micrometers and 1000 micrometers, and preferably of between 500 micrometers and 5800 micrometers.

[0045] The branches 46 of at least one electrode among the first electrode and the second electrode, have a dimension 1 in the secondary direction P2 of between 3 millimeters and 20 millimeters, and preferably of between 3 and 7 millimeters. The secondary direction P2 is perpendicular to the main direction PL

[0046] The branches 46 of the first electrode 40 comprise free ends 48. A free end 48 of a branch of the first electrode is spaced from a portion of the rod of the second electrode arranged opposite the latter, by a spacing S of between 250 micrometers and 1000 micrometers, and preferably between 500 micrometers and 800 micrometers.

[0047] The rods 44 have a length Ltot along the main direction PI of between 3 and 6 centimeters.

[0048] The capacitive sensor 22 has a width Latot along the secondary direction P2 of between 0.5 and 2 centimeters.

[0049] The invention relates to a device 50 for detecting the size of an occupant of a seat, in particular a motor vehicle seat, the detection device comprises the first flexible support 20 extending in the longitudinal direction Z; - at least the first capacitive sensor 22 and the second capacitive sensor 24, and - electrical connection wires 27, 29 connected to the first capacitive sensor 22 and to the second capacitive sensor 24. The electrical connection wires 27, 29 extend along the longitudinal direction Z. The first capacitive sensor and the second capacitive sensor each extend perpendicular to the longitudinal direction Z. The second capacitive sensor 24 being advanced by a first distance DI relative to the first capacitive sensor 22 in the direction of the lateral edge; the first distance (Dl), measured in a transverse direction (Y), being equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

[0050] The detection device may also comprise all of the characteristics mentioned above and in particular a greater number of capacitive sensors and a second flexible support.

Claims

Claims

1. Backrest (6) of a seat (2), in particular a backrest of a motor vehicle seat, the backrest extending in a longitudinal direction (Z) and a transverse direction (Y); said backrest comprising: - at least a first (22) and a second (24) capacitive sensors with coplanar interdigitated electrodes called first and second first-zone capacitive sensors, said first-zone capacitive sensors being arranged on a first zone (16) of the backrest located above a horizontal central plane (X, Y) and on one side of a vertical central plane (X, Z); the second first-zone capacitive sensor (24) being located above the first first-zone capacitive sensor (22); the second first-zone capacitive sensor (24) being advanced by a first distance (Dl) relative to the first first-zone capacitive sensor (22) in the direction of the vertical central plane (X, Z).

2. File (6) according to claim 1, in which the first distance (Dl) measured in the transverse direction (Y) is equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

3. Backrest (6) according to claim 2, which comprises at least one third capacitive sensor (26) with coplanar interdigitated electrodes called third first-zone capacitive sensor; said third first-zone capacitive sensor (26) being arranged on the first zone (16) of the backrest; the third first-zone capacitive sensor (26) being located above the second first-zone capacitive sensor (24); the third first-zone capacitive sensor (26) being advanced by a second distance (D2) relative to the second first-zone capacitive sensor (24) in the direction of the vertical central plane (X, Z); the second distance (D2) measured in the transverse direction (Y) being in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

4. Backrest (6) according to claim 3, which comprises at least one fourth capacitive sensor (28) with coplanar interdigitated electrodes called fourth capacitive sensor of first zone; said fourth capacitive sensor (28) of first zone being arranged on the first zone (16) of the backrest; the fourth capacitive sensor of first zone being located above the third capacitive sensor (26) of first zone; the fourth capacitive sensor (28) of first zone being advanced by a third distance (D3) relative to the third capacitive sensor (26) of the first zone in the direction of the vertical central plane (X, Z); the third distance (D3) measured in the transverse direction (Y) being in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

5. File (6) according to any one of claims 1 to 4, in which two capacitive sensors (22, 24, 26, 28) of first zone, arranged next to each other in the longitudinal direction (Y), are spaced from each other by a gap (E) of between 5 millimeters and 20 millimeters.

6. Backrest (6) according to any one of claims 1 to 5, which further comprises at least a first (32) and a second (34) second zone capacitive sensor (18); said first (32) and second (34) second zone capacitive sensors being arranged on a second zone (18) of the backrest; said second zone being located above the horizontal central plane (X,Y) and on the other side of the vertical central plane (X,Z); the second second zone capacitive sensor (34) being located above the first second zone capacitive sensor (32); the second second zone capacitive sensor (34) being advanced by a fourth distance (D4) relative to the first second zone capacitive sensor (32) in the direction of the vertical central plane (X,Z); the fourth distance (D4) measured in the transverse direction (Y) being in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

7. Backrest (6) according to claim 6, which comprises at least one third capacitive sensor (36) with coplanar interdigitated electrodes called third capacitive sensor of second zone, said third capacitive sensor (36) of second zone being arranged on the second zone (18) of the backrest; the third capacitive sensor (36) of second zone being located above the second capacitive sensor (34) of second zone; the third capacitive sensor (36) of second zone being advanced by a fifth distance (D5) relative to the second capacitive sensor (34) of second zone in the direction of the vertical central plane (X,Z); the fifth distance (D5) being measured in the transverse direction (Y); the fifth distance (D5) being in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

8. File (6) according to claim 7, which comprises at least one fourth capacitive sensor (38) with coplanar interdigitated electrodes called fourth second-zone capacitive sensor, said fourth second-zone capacitive sensor (38) being arranged on the second zone (18) of the backrest; the fourth second-zone capacitive sensor (38) being located above the third second-zone capacitive sensor (36); the fourth second-zone capacitive sensor (38) being advanced by a sixth distance (D6) relative to the third capacitive sensor (36); the sixth distance (D6), measured in the transverse direction (Y); is in particular equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.

9. File (6) according to any one of claims 6 to 8, in which at least two capacitive sensors (22, 24, 26, 28) of first zone and two capacitive sensors (32, 34, 36, 38) of second zone are arranged symmetrically with respect to each other, with respect to the central vertical plane (X, Z).

10. Backrest (6) according to any one of the preceding claims, which further comprises electrical connection wires (27, 29, 37, 39) each connected to a first zone capacitive sensor (22, 24, 26, 28) and / or to a second zone capacitive sensor (32, 34, 36, 38); and a flexible support (20, 30) carrying the capacitive sensors and the electrical connection wires; a part of the flexible support (30, 40) being arranged on an upper edge of the backrest, next to the headrest (7).

11. File (6) according to any one of the preceding claims, in which at least one capacitive sensor (22, 24, 26, 28, 32, 34, 36, 38) with coplanar interdigital electrodes comprises a first electrode (40) and a second electrode (42), the first electrode (40) and the second electrode (42) each comprising a rod (44) extending in a main direction (PI), and branches (46) integral with the rod, the branches (46) extending in a secondary direction (P2), the secondary direction (P2) being perpendicular to the main direction (PD; the branches (46) of the first electrode being separated from each other by the same interval (IN); the branches (46) of the first electrode (40) being interposed between the branches (46) of the second electrode (42);the rod (44) and the branches (46) of at least one electrode among the first electrode and the second electrode, having a dimension (ed) in the main direction (PI) of between 250 micrometers and 1000 micrometers, and preferably of between 500 micrometers and 800 micrometers.;

12. File (6) according to claim 9 in which the branches (46) of at least one electrode among the first electrode and the second electrode, have a dimension (1) in the secondary direction (P2) of between 3 millimeters and 20 millimeters, and preferably of between 3 and 7 millimeters.

13. File (6) according to any one of claims 9 and 10, the branches (46) of the first electrode (40) have free ends (48), and in which a free end (48) of a branch (46) of the first electrode is spaced from a portion of the rod of the second electrode arranged opposite the latter, by a spacing (S) of between 250 micrometers and 1000 micrometers, and preferably between 500 micrometers and 800 micrometers.

14. Device (50) for detecting the size of an occupant of a seat for a seat back, in particular a motor vehicle seat, the back extending in a longitudinal direction (Z) and a transverse direction (Y); the detection device (50) comprising: - at least one flexible support (20, 30) having a strip shape having two lateral edges (23), the flexible support (20, 30) extending in a longitudinal direction (Z); - at least a first (22, 32) and a second (24, 34) capacitive sensors with coplanar interdigitated electrodes called first and second capacitive sensors, and - electrical connection wires (27, 29, 37, 39) connected to the first (22, 32) and to the second (24, 34) capacitive sensors and extending in the longitudinal direction (Z);the first and second capacitive sensors extending perpendicular to the longitudinal direction (Z), the flexible support being shaped to be arranged on the seat backrest so that said capacitive sensors are arranged on a first area (16) of the backrest located above a horizontal central plane (X,Y) and on one side of a vertical central plane (X,Z); the second capacitive sensor (24) being advanced by a first distance (Dl) relative to the first capacitive sensor (22) in the direction of a lateral edge (23); the first distance (Dl), measured in a transverse direction (Y), being equal to or greater than 5 millimeters, and preferably equal to or greater than 10 millimeters.;

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