FR2866846A1 - Motor vehicle occupant head position detecting system, has two sensors integrated in headrest and providing respective signals representative of two different ranges, where one range is lower than another range - Google Patents

Abstract

The system has two sensors integrated in a headrest (5) and transmitting a signal representative of distance which separates them from the head of a vehicle occupant. The two sensors are adapted to provide respective signals representative of two different ranges (L1, L2), where one range is lower than another range. A sensor layer (19) comprises a plastic film on which are fixed the sensors. An independent claim is also included for a seat for motor vehicle comprising a detection system and a head rest.

Description

Detection system of the position of the head of a

  The present invention relates to systems for detecting the position of the head of an occupant by means of a headrest of a motor vehicle seat, and head restraint and seat provided with such a detection system. in relation to a headrest of a motor vehicle seat and to head restraints and seats fitted with such a detection system.

  More particularly, the invention relates to a system for detecting the position of the head of an occupant relative to a headrest of a motor vehicle seat, said system comprising at least first and second sensors intended to be integrated. in said headrest, said first and second sensors each being adapted to emit a signal representative of a distance separating them from the head of the occupant.

  The document DE 199 16 804 describes an example of such a detection system, where the signals emitted by the two identical sensors are compared to evaluate the height of the head relative to the headrest.

  The height of the head relative to the headrest is information that can in particular be used by a central unit during a shock of the vehicle, for example to trigger the inflation of an airbag (during a shock front or side), or to activate an anti-whiplash safety system, for example of the kind that quickly brings the headrest closer to the head (in the event of a rear impact) depending, among other things, on the height of the head.

  Such sensors, however, have a limited range, and when the head is away from the headrest, the detection of the distance from the head to the headrest is unreliable. This is particularly damaging insofar as it is precisely when the head is very far from the headrest that it is necessary to know precisely its position to ward off the best whiplash in case of rear impact. To overcome this drawback, one could be tempted to increase the range of the two sensors in particular by increasing their area. Nevertheless, this would have major disadvantages in that, firstly, the size of the sensors is in any case limited so that the two sensors can enter the headrest, secondly, the sensors being located in the rather central position of the head restraint in DE 199 16 804, the increase in size is mainly to the upper or lower ends and side of the head restraint where the detection is of less interest, and third, the cost of the sensor will increase overall in proportion to its area.

  The present invention is intended to overcome at least one of these disadvantages.

  For this purpose, according to the invention, a detection system of the kind in question is essentially characterized in that the first sensor is adapted to emit a signal representative of a distance over a first range of distances and the second sensor is adapted to transmit a signal representative of a distance only over a second range of distances less than the first range of distances.

  Thanks to these arrangements, it is possible to use only one (first) extended sensor to identify the position remote from the head, and at least one second sensor of small area to accurately detect the position of the head relative to the headrest when it is close to this one.

  In preferred embodiments of the invention, one or both of the following arrangements may be furthermore used: said first and second sensors are aligned in a first direction, and the system detection device further comprises a third sensor, adapted to transmit a signal representative of a distance on said second range of distances, said first and third sensors being aligned in a second direction different from the first direction; the detection system further comprises fourth and fifth sensors adapted to transmit a signal representative of a distance on said second range of distances, said second, third, fourth and fifth sensors being arranged to form a quadrilateral, and said first sensor being disposed within said quadrilateral; said sensors are capacitive sensors; the detection system comprises a flexible detection sheet comprising at least one flexible sheet on which said sensors are fixed; - The detection system further comprises a central unit, said sensors transmitting said central unit said signals, and said central unit being adapted to determine the position of the head of the occupant from said signals.

  According to another aspect, the invention relates to a headrest for a vehicle seat comprising such a detection system.

  In a preferred embodiment of the invention, the following arrangement may optionally be used: said headrest comprises at least one pin on which a flexible padding is mounted, said soft padding being covered with a dressing cap, a portion of which forms a bearing surface for the head of the occupant, and wherein said ply is inserted between said padding and said cap.

  According to another aspect, the invention relates to a seat for a vehicle comprising such a detection system, said seat comprising: - a backrest provided with a fixed portion, - a headrest movably mounted relative to said fixed portion, and wherein said sensors are integrated, at least one motorized device adapted to move said headrest relative to said fixed portion, the motorized device being controlled by said central unit to move said headrest relative to said fixed portion as a function of said position of the head determined by the central unit.

  In a preferred embodiment of the invention, the following arrangement may also be used: the headrest is movably mounted relative to said fixed portion at least along a translation axis, essentially vertical and about an axis of rotation, substantially transverse, the motorized device being controlled to move said headrest relative to said fixed portion along said axis of translation and about said axis of rotation, so that said headrest follow said head.

  Other features and advantages of the invention will become apparent from the following description of one of its embodiments, given by way of non-limiting example, with reference to the accompanying drawings.

  In the drawings: FIG. 1 is a side view of a seat according to the invention; FIG. 2 is a schematic perspective view of a seat head restraint structure of FIG. FIG. 3 represents a diagrammatic sectional view along the line III-III of FIG. 2; FIG. 4 is a schematic plan view of an exemplary embodiment of a sheet of sensors used in the context of the invention; FIG. 5 is an example of a main sensor variant of the sensor array of FIG. 4.

  In the different figures, the same references designate identical or similar elements.

  FIG. 1 represents a vehicle seat, in particular a front seat of a motor vehicle, which comprises, on the one hand, a seat 2 mounted on the floor 3 of the vehicle, and, on the other hand, a backrest 4 which bears a headrest 5, and which can be pivotally mounted on the seat 2 around a transverse horizontal axis Y1 by means of a hinge mechanism (not shown) which makes it possible to adjust the overall inclination of the backrest 4.

  The backrest 4 comprises a rigid structure 6, part of which is visible in FIG. 2, and on which is mounted a flexible lining 7, for example made of synthetic foam or the like, covered towards the outside of the seat by a covering cap. .8 textile, leather or other.

  The rigid structure 6 may comprise in particular an upper cross member 9, in the upper part of the backrest, extending mainly horizontally in a transverse direction of the backrest.

  The headrest 5 is mounted on the rigid structure 6, for example by two pins 10 which are slidably mounted on the upper crosspiece 9. These two pins 10 each have in the headrest a ring-shaped end 10a in which is inserted an axis 14 carrying the headrest 5. This axis 14 is rotatably mounted in the two rings 10a of the pins 10.

  The headrest 5 is movably mounted relative to the rigid structure 6 backrest having in general with respect to this rigid structure of 1 to 5 degrees of freedom. The headrest can in particular be able to slide relative to the rigid structure vertically, laterally, and / or from front to back, and can also be pivotable relative to the rigid structure about a vertical or transverse axis, some these translational and rotational movements being optionally combined.

  The embodiment presented here in connection with FIG. 2 allows the headrest 5 to perform, on the one hand, an almost vertical movement along a Z axis for positioning the headrest in height. relative to the rigid structure 6 of the backrest, and secondly, a rotational movement of the headrest 5 relative to a transverse axis Y2 transverse seat 1 parallel to Y1. Nevertheless, the invention is applicable to all types of movable head restraints with respect to a rigid structure of the backrest, by translational movements and / or rotation, or combined movements previously described. In addition, it is not necessary that the headrest alone is movable relative to a rigid structure of the file, but it may be a seat in which an upper part of the rigid structure carrying the support - Head is movable relative to a fixed portion of the rigid backrest structure.

  In the embodiment of Figure 2, the two pins 10 of the headrest are slidably mounted relative to the upper cross member 9 of the rigid backrest structure, and a first motor 11 can control the sliding of a rod 12 inside a support 13 fixedly mounted on the upper cross member 9. The lower end of the rod 12 is fixed on a connecting element 12a on which are also secured the lower ends of the pins 10. The first motor 11 thus controls the quasi-vertical displacement of the headrest 5 along the Z axis. The axis 14 situated in the headrest 5 is able to pivot in the upper ends 10a of the pins 10 shaped into rings. The axis 14 is provided with a ring gear 15 whose teeth cooperate, in a certain angular range, with the teeth of a ring gear 16 mounted on an axis 16a itself rotatably supported by the pins 10. A second motor 17 controls the rotation in one direction or the other of the axis 16a and thus the second ring gear 16, which carries with it the first ring gear 15 and the headrest 5 in rotation around the Y2 axis.

  The head restraint just described is shown in Figure 3 in a section along the line III-III of Figure 2. The headrest in question consists essentially of a padding 18, of polygonal or other shape, a front face 18a is oriented towards the head of a seat occupant. Said front face 18a receives a sheet of sensors 19 forming part of an occupant presence detection system. A covering cap 20, for example of fabric, leather, synthetic, or other, covers said sheet of sensors 19 and has a bearing surface 20a in contact with which is placed the head of a seat occupant, by example a passenger of a motor vehicle, in a rest position. The headrest may, in addition, present, interposed between the sensor web 19 and the covering cap 20, a protective film 21 consisting for example of a polyethylene-type waterproof material, or other, protecting the water table. sensors 19 of humidity or significant temperature variations.

  Such an arrangement allows easy industrialization of a detection system in a headrest.

  FIG. 4 represents the layer of sensors 19 of FIG. 3 deployed and laid flat in the plane Y2, Z. Such a sheet of sensors 19 comprises, for example, a flexible plastic film 22 that is sufficiently flexible to be able to envelop the front face 18a of the padding 18 of the headrest 5, and on which are fixed, by gluing, sewing or other, a first presence sensor 23 and a set of second presence sensors 24a to 24d, different from the first sensor 23.

  These sensors are for example of the capacitive type and are adapted to detect variations in the electrical permittivity of the surrounding space, and in particular of the space directly in front of the headrest 5. The first sensor 23 is composed of for example a first electric plate 23a, here in the form of a metal film which has been given the shape of a comb, and a second metal plate 23b located at the rear of the first plate 23a, possibly being separated therefrom by an insulating film (not shown). These metal films are also sufficiently flexible so that the web 19 can wrap the padding 18 without interfering with the comfort of the occupant.

  During a first phase, the plate 23a, for example, is placed at a given electric potential by an electric generator (not shown), then, during a second phase, the electric generator in question is cut off, so that the capacitor formed by the plates 23a and 23b of the sensor is discharged, and emits an electrical signal, raised by a central unit, not shown, representative of the electrical permittivity of the surrounding medium. In particular, the signal emitted depends on the presence or absence of the head of a seat occupant in the vicinity of the sensor.

  Alternatively, a second plate 23b will not necessarily be used, but any metal element forming part of the seat structure may be used.

  In the context of the invention, the first sensor 23 has a large range, sufficient to detect the presence of the head of an occupant located even relatively far from the headrest, corresponding to a first range of distances L1. As shown in FIG. 3, a driver of a vehicle who drives in an active posture in which the head is at a distance from the head restraint 5 is considered. The increased range of the first sensor 23 is example provided by its comb shape which allows it to have an extended perimeter while remaining confined in a limited space, these two parameters being factors determining the range of such a capacitive presence sensor. The first presence sensor 23 will preferably be, as shown in FIG. 4, disposed in the center of the sensor web, having a width and height between about 4 and 34 of the width, and the height, respectively, of the head restraint.

  Such a first presence sensor 23 effectively detects the distance between the head of the occupant and the headrest 5 on the first range of distances L1, and transmit this information to the central unit (not shown) which can use this information in various ways, for example in case of shock to set the triggering of a front airbag, or side of the vehicle.

  The sensor array 19 further comprises at least one second sensor 24a, 24b, 24c, 24d or, as shown, a plurality of second sensors of this type, having a smaller detection range than the first sensor 23. These second sensors are for example in the form of a first electrically conductive film 24a1 and a second electrically conductive film 24a2 separated by an insulating film 24a3, and are also relatively flexible. These second sensors are of the same type as the first sensor, but, having only a small detection range, they can reliably detect that the presence of a head of an occupant very close to the headrest 5 corresponding to a second range of distances L2 less than the first range of distances L1 of the first sensor 23. It is particularly, but not exclusively, thought of a seat passenger of a motor vehicle having placed his head on the headrest 5 in question.

  The first sensor 23 and the second sensor 24a are in particular arranged along an axis s, and the study by the central unit of the signals emitted on the one hand by the first sensor 23 and on the other hand by the second sensor 24a makes it possible to obtain information on the position of the head of the occupant along the axis s. Thus, the simultaneous study of these two signals makes it possible to obtain information relating to the position of the head in the passenger compartment of the vehicle. Such information may also be useful, for example for triggering one or more airbags. If the sensor 24a is placed on the window side, it is easy to understand that one will obtain in this way information relating to the lateral position of the head of the occupant, which can be decisive when inflating a curtain airbag located in the window. door in case of side impact.

  It is also possible to use a second sensor 24b, similar in type to the second sensor 24a, so that the sensors 23, 24a and 24b are not aligned. The sensor 23 and the sensor 24b extend, for example, along an axis t different from the axis s. The simultaneous processing by the central unit of the signals emitted by the sensors 23, 24a and 24b will make it possible to determine with even more precision the position of the head of the occupant in the plane (s; t).

  Thus, as shown in FIG. 4, four sensors 24a, 24b, 24c, 24d can be arranged at the four corners of the sensor array 19, and the information from each unit can be processed using the central unit. of these sensors to accurately determine the position of the head relative to the headrest. We can of course use more than four second sensors.

  In addition, when many second sensors are available, the signal emitted by the sensor 23 will no longer necessarily be used when the head is in close proximity to the headrest.

  Knowing the position of the headrest in the vehicle, it is thus possible to determine the position of the head in three dimensions in the passenger compartment of the vehicle.

  The information emitted by the sensors 23, 24a, 24b, 24c and 24d is not necessarily only used to trigger or not the inflation of airbags, for example in case of shock of the vehicle. In particular, it is possible for the signal emitted by the first sensor 23 to enable the central unit to detect the distance between the occupant's head and the headrest 5, and that, therefore, if this distance is judged high by the central unit, that it controls one of the motors 11, 17 (Figure 2) to move the headrest 5 relative to the rigid structure 6 of the folder, so as to bring the headrest 5 of the occupant's head. As the headrest 5 approaches the head of the occupant, the signal emitted by the first sensor 23, but most importantly, the signals emitted by the second sensors 24a, 24b, 24c and 24d become more reliable, and allow to accurately determine the position of the head in the passenger compartment. Once such a position determined by the central unit, it can emit a signal precisely controlling the motors 11, 17 (Figure 2) to accurately guide the headrest in an optimal position relative to the head. In particular it can be provided that the headrest thus controlled can follow the movements of the head of the occupant. This ensures that the headrest is always in an optimal position for both occupant comfort and safety in the event of a rear impact.

  According to an alternative embodiment shown in Figure 5, the first sensor 23 may be in the form of a double comb, for example symmetrical with respect to an axis corresponding to the axis Y2 of the headrest.

  The total width of such a sensor 23 is for example 19 cm, and its height of about 15 cm.

  According to another variant embodiment, the sensitivity of the sensor layer to the external conditions will be reduced by placing behind it a metal plate.

  For a headrest with mechanical or manual inclination adjustment, provision may further be made for the signal emitted by each primary or secondary sensor to be weighted by a predetermined factor related to the angular inclination of the headrest. The angular inclination of the headrest can be provided to the central unit by a tilt sensor, located for example in the headrest, detecting the orientation of the headrest relative to a position predetermined of it.

Claims (10)

  1. System for detecting the position of the head of an occupant relative to a headrest (5) of a seat 5 of a motor vehicle, said system comprising at least first (23) and second (24a) sensors intended to be integrated in said headrest, said first and second sensors being each adapted to emit a signal representative of a distance which separates them from the head of the occupant, characterized in that the first sensor is adapted to emit a signal representative of a distance over a first range of distances (L1) and the second sensor (24a) is adapted to output a signal representative of a distance only over a second range of distances (L2) less than the first range of distances .   2. Detection system according to claim 1, wherein said first (23) and second (24a) sensors are aligned in a first direction (s), and further comprising a third sensor (24b), adapted to emit a representative signal a distance on said second range of distances (L2), said first (23) and third (24b) sensor being aligned in a second direction (t) different from the first direction.   3. Detection system according to claim 2, further comprising fourth (24c) and fifth (24d) sensors adapted to emit a signal representative of a distance on said second range of distances (L2), said second, third, fourth and fifth sensors being arranged to form a quadrilateral, and said first sensor being disposed within said quadrilateral.   4. Detection system according to any one of the preceding claims, wherein said sensors are capacitive sensors.   5. Detection system according to any one of the preceding claims, comprising a flexible detection web (19) comprising at least one sheet (22) flexible on which are fixed said sensors (23, 24a, 24b, 24c, 24d).   6. Detection system according to any one of the preceding claims, further comprising a central unit, said sensors transmitting said signals to said central unit, and said central unit being adapted to determine the position of the head of the occupant from said signals.   Headrest for a vehicle seat comprising a detection system according to any one of claims 1 to 5.   8. A headrest for a vehicle seat comprising a detection system according to claim 5, said headrest comprising at least one pin (10) on which is mounted a soft padding (18), said flexible padding being covered with a covering cap (20), a portion of which forms a bearing surface (20a) for the head of the occupant, and wherein said ply (19) is inserted between said padding (18) and said cap (20).   9. Seat for a vehicle comprising a detection system according to claim 6, said seat comprising: a backrest (4) provided with a fixed portion (6), a headrest (5) mounted movably relative to said portion fixed (6), and wherein said sensors (23, 24a, 24b, 24c, 24d) are integrated, - at least one motorized device (11, 17) adapted to move said headrest (5) relative to said portion fixed (6), the motorized device (11, 17) being controlled by said central unit to move said headrest relative to said fixed portion according to said position of the head determined by the central unit.   10. Seat according to claim 9, wherein the headrest (5) is mounted to move relative to said fixed portion at least along a translation axis (z), substantially vertical and about an axis of rotation (Y2), essentially transverse, the motorized device (11, 17) being controlled to move said headrest (5) relative to said fixed portion (6) along said translation axis (Z) and about said axis of rotation. rotation (Y2), so that said headrest follows said head.