Abstract:
An apparatus ( 10 ) for use with a removable child seat ( 12 ) in a vehicle ( 14 ) comprises a vehicle seat ( 20 ) on which a removable child seat may or may not be present, and a seat belt webbing pretensioner ( 40 ) for retracting seat belt webbing ( 30 ) associated with the vehicle seat. A first sensor ( 58 ) provides a first output signal in response to a vehicle collision of a magnitude above a predetermined threshold. A second sensor ( 60 ) provides a second output signal in response to the presence of a child seat ( 12 ) on the vehicle seat ( 20 ). A controller ( 50 ) receives the first and second output signals and, in response to the first output signal, actuates the seat belt webbing pretensioner ( 40 ) when a child seat ( 12 ) is not present on the vehicle seat ( 20 ) and inhibits actuation of the seat belt webbing pretensioner when a child seat is present on the vehicle seat.

Description:
TECHNICAL FIELD 
     The present invention relates to an apparatus for use with a removable child seat in a vehicle having a seat belt webbing pretensioner. The present invention is particularly directed to an apparatus for disabling the seat belt webbing pretensioner associated with a given vehicle seat when a removable child seat is located on that vehicle seat. 
     BACKGROUND OF THE INVENTION 
     It is known to sense the presence of a rearward facing infant child seat in a vehicle, and to prevent the actuation of an inflatable occupant restraint, such as an air bag, when the presence of such a child seat is sensed. The rearward facing infant child seat is detected using an identifiable tag attached to the child seat and an antenna coil mounted in the vehicle. The antenna coil transmits an EMF signal to the tag, which, in turn, returns a signal to the antenna coil indicating the presence of the rearward facing infant child seat on the vehicle seat. 
     It is also known to utilize a seat belt webbing pretensioner to help protect a vehicle occupant from injury during a vehicle collision. The seat belt webbing pretensioner is actuatable to retract seat belt webbing extending over the body of the vehicle occupant and thereby to remove any slack in the seat belt webbing immediately prior to the vehicle collision. 
     If a child seat is secured to a vehicle seat by seat belt webbing having an associated pretensioner, it is desirable to disable the pretensioner. It is further desirable to disable the pretensioner regardless of whether the child seat is rearward facing or forward facing or whether the child seat is located on a front seat of the vehicle or on a rear seat of the vehicle. 
     SUMMARY OF THE INVENTION 
     An apparatus for use with a removable child seat in a vehicle comprises a vehicle seat on which a removable child seat may or may not be present, and a seat belt webbing pretensioner for retracting seat belt webbing associated with the vehicle seat. A first sensor provides a first output signal in response to a vehicle collision of a magnitude above a predetermined threshold. A second sensor provides a second output signal in response to the presence of a child seat on the vehicle seat. A controller receives the first and second output signals and, in response to the first output signal, actuates the seat belt webbing pretensioner when a child seat is not present on the vehicle seat and inhibits actuation of the seat belt webbing pretensioner when a child seat is present on the vehicle seat. 
     A pretensioner actuation circuit for actuating the seat belt webbing pretensioner is electrically connected with and controlled by the controller. The second sensor comprises an antenna coil mounted in the vehicle and an identification tag for attachment to a child seat. The antenna coil is adapted to transmit an electromagnetic field (EMF) signal to the identification tag and to receive a return EMF signal from the identification tag. The identification tag is adapted to receive an EMF signal from the antenna coil and to use energy of the received EMF signal to generate a return EMF signal. 
     In accordance with certain embodiments of the present invention, the vehicle seat comprises one of a front passenger seat and a rear passenger seat and a child seat is locatable on the one passenger seat to face rearward of the vehicle. 
     In accordance with other embodiments of the invention, the vehicle seat comprises one of a front passenger seat and a rear passenger seat and a child seat is locatable on the one passenger seat to face forward of the vehicle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic illustration of an apparatus for use with a removable child seat in a vehicle having a seat belt webbing pretensioner; 
     FIG. 2 illustrates a second embodiment of the present invention; 
     FIG. 3 illustrates a third embodiment of the present invention; 
     FIG. 4 illustrates a fourth embodiment of the present invention; 
     FIG. 5 illustrates a fifth embodiment of the present invention; 
     FIG. 6 illustrates a sixth embodiment of the present invention; 
     FIG. 7 illustrates a seventh embodiment of the present invention; and 
     FIG. 8 illustrates an eighth embodiment of the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 schematically illustrates an apparatus  10  for use with a removable child seat  12  in a vehicle  14  having a seat belt webbing pretensioner  40 . The vehicle  10  includes an instrument panel  18  and a vehicle seat  20  having a seat cushion  22  and a seat back  24 . In accordance with a first embodiment of the present invention, the vehicle seat  20  illustrated in FIG. 1 is a front passenger seat. 
     The child seat  12  is secured to the vehicle seat  20  in a rearward facing direction, indicated by arrow A, by seat belt webbing  30 . The seat belt webbing  30  is secured to the vehicle floor on an inboard side  32  of the vehicle seat  20  through a mounting assembly  34  and a buckle  36 , as is well known in the art. The seat belt webbing  30  extends through a belt holder  37  of the child seat  12  and is secured to the vehicle floor on an outboard side (not shown) where a seat belt webbing retractor (not shown) is located. The child seat  12  includes a three-point restraining harness  38  that is typical for removable child seats. 
     The seat belt webbing pretensioner  40  is a known device secured inside the mounting assembly  34 . The pretensioner  40  is actuatable by an electrical signal. When actuated, the pretensioner  40  pulls the buckle  36  toward the mounting assembly  34  and tightens the seat belt webbing  30  immediately prior to a vehicle collision, as is known in the art. 
     The apparatus  10  includes a controller  50  operatively connected to a driver/receiver circuit  52 . The controller  50  is further controllably connected to a pretensioner actuation circuit  54  and to a visual warning indicator  56  mounted in the instrument panel  18 . The pretensioner actuation circuit  54  is operatively coupled with the seat belt webbing pretensioner  40 . 
     At least one vehicle crash sensor  58  is mounted in the vehicle  14 . The crash sensor  58  is electrically connected to and monitored by the controller  50 . The crash sensor  58  can be any of several known crash sensors, including inertia switches or accelerometers, that provide an electric signal to the controller  50  indicative of sudden vehicle deceleration above a predetermined magnitude. 
     The driver/receiver circuit  52  is operatively connected with an antenna coil  60 . The antenna coil  60  is located in the seat back  24  of the vehicle seat  20  near where the seat back meets the seat cushion  22 . The driver/receiver circuit  52  is operable to energize the antenna coil  60  with periodic pulses and then monitor the antenna coil for a returning electromagnetic field (EMF) signal. 
     The apparatus  10  further includes a child seat identification tag  62  secured to the child seat  12 . The tag  62  is secured near a front end  64  of the child seat  12  by appropriate securing means, such as glue, or by injection molding the tag into a plastic part of the child seat. When the child seat  12  is secured in the rearward facing direction A on the front passenger seat  20  as shown in FIG. 1, the front end  64  of the child seat  12  is adjacent the seat back  24  of the passenger seat. The distance between the antenna coil  60  in the seat back  24  and the identification tag  62  on the child seat  12  is a few inches or less, and is well within the effective range of an EMF signal transmitted by the antenna coil. 
     As set forth in detail in U.S. Pat. No. 5,683,103, the tag  62  is made from a highly permeable amorphous material that is reactive when subjected to an EMF signal. When the tag  62  is within the range of the EMF signal produced by the energized antenna coil  60 , the tag&#39;s amorphous material is stressed by the EMF signal, thereby creating a change in the magnetic permeability of the material. This change in the magnetic permeability results in passive EMF waves radiating from the tag  62  at the tag&#39;s mechanical natural frequency. The EMF waves radiating from the tag  62  are received by the antenna coil  60  and are transformed by the antenna coil into a received signal which is recognizable by the driver/receiver circuit  52 . 
     When the vehicle&#39;s electrical system is active, the driver/receiver circuit  52  continuously energizes the antenna coil  60  to produce an EMF signal. The driver/receiver circuit  52  simultaneously continuously monitors the antenna coil  60  for a return EMF signal radiating from the tag  62  on the child seat  12 . When the child seat  12  is present on the passenger seat  20 , a return signal from the tag  62  is detected by the driver/receiver circuit  52 . The driver/receiver circuit  52  then sends a corresponding signal to the controller  50  indicating the presence of the child seat  12  on the passenger seat  20 . Based on this signal, the controller  50 , through appropriate circuitry (not shown), inhibits actuation of the pretensioner  40  by electrically disabling the pretensioner actuation circuit  54 . The controller  50  also causes the warning indicator  56  in the instrument panel  18  to illuminate, thereby informing the vehicle occupants that the pretensioner  40  associated with the passenger seat  20  on which the child seat  12  is located is disabled. 
     When the vehicle&#39;s electrical system is active, the controller  50  is continuously monitoring the output of the crash sensor  58 . If the crash sensor  58  detects sudden vehicle deceleration above a predetermined magnitude indicative of a vehicle collision, the crash sensor sends a signal to the controller  50 . If the controller  50  has disabled the pretensioner actuation circuit  54  because the child seat  12  is present on the passenger seat  20 , the pretensioner  40  associated with that passenger seat will not be actuated. It should be understood that pretensioners (not shown) associated with other seats (not shown) in the vehicle  14  may nevertheless be actuated by the controller  50  when a vehicle collision is detected. However, if the controller  50  has not disabled the pretensioner actuation circuit  54  because the child seat  12  is not present on the passenger seat  20 , the pretensioner  40  associated with that passenger seat will be actuated to remove slack in the seat belt webbing  30  early in the vehicle collision. 
     FIG. 2 illustrates an apparatus  10 A constructed in accordance with a second embodiment of the present invention in which the respective locations of the antenna coil  60  and the tag  62  are different from the embodiment of FIG.  1 . Otherwise, the remainder of the structure is the same as described above regarding the embodiment of FIG.  1 . As shown in FIG. 2, the antenna coil  60  is mounted in the instrument panel  18  and the identification tag  62  is secured to an upper rear portion  66  of the child seat  12 . Those skilled in the art will appreciate that the circuitry in the driver/receiver circuit  52  and in the controller  50  will be selected to compensate for the increased distance between the antenna coil  60  and the tag  62 . 
     The apparatus  10 A according to the second embodiment functions in the same manner as the embodiment of FIG. 1 to inhibit actuation of the pretensioner  40  when the child seat  12  is present on the vehicle seat  20 . 
     FIG. 3 illustrates an apparatus  10 B constructed in accordance with a third embodiment of the present invention. In FIG. 3, the child seat  12  is secured to the vehicle seat  20  in a forward facing direction, indicated by arrow B, by the seat belt webbing  30 . The respective locations of the antenna coil  60  and the tag  62  are also different from the embodiments of FIGS. 1 and 2. Otherwise, the remainder of the structure is the same as described above regarding the previous embodiments. As shown in FIG. 3, the antenna coil  60  is mounted in an upper portion  70  of the seat back  24  of the passenger seat  20  while the identification tag  62  is secured to the upper rear portion  66  of the child seat  12 . Those skilled in the art will appreciate that the circuitry in the driver/receiver circuit  52  and in the controller  50  will be selected to accommodate for the distance between the antenna coil  60  and the tag  62 . 
     The apparatus  10 B according to the third embodiment functions in the same manner as the previous embodiments to inhibit actuation of the pretensioner  40  when the child seat  12  is present on the vehicle seat  20 . 
     FIG. 4 illustrates an apparatus  10 C constructed in accordance with a fourth embodiment of the present invention. In FIG. 4, the child seat  12  is secured to the vehicle seat  20  in the forward facing direction B by the seat belt webbing  30 . Otherwise, the remainder of the structure is the same as described above regarding the previous embodiments. As shown in FIG. 4, the antenna coil  60  is mounted in the instrument panel  18  while the identification tag  62  is secured to the front end  64  of the child seat  12 . Those skilled in the art will appreciate that the circuitry in the driver/receiver circuit  52  and in the controller  50  will be selected to accommodate for the distance between the antenna coil and the tag. 
     The apparatus  10 C according to the fourth embodiment functions in the same manner as the previous embodiments to inhibit actuation of the pretensioner  40  when the child seat  12  is present on the vehicle seat  20 . 
     FIG. 5 illustrates an apparatus  10 D constructed in accordance with a fifth embodiment of the present invention which differs from the embodiment of FIG. 1 only in that the child seat  12  is secured to a rear passenger seat  80  in the vehicle  14 , rather than the front passenger seat  20 . Otherwise, the remainder of the structure is the same as described above regarding FIG.  1 . The apparatus  10 D according to the fifth embodiment functions in the same manner as the previous embodiments to inhibit actuation of the pretensioner  40  when the child seat  12  is present on the rear passenger seat  80 . 
     FIG. 6 illustrates an apparatus  10 E constructed in accordance with a sixth embodiment of the present invention which differs from the embodiment of FIG. 2 in that the child seat  12  is secured to the rear passenger seat  80  in the vehicle  14 . Further, the antenna coil  60  is mounted in the upper portion  70  of the seat back  24  of the front passenger seat  20  and faces toward the rear seat  80 . Otherwise, the remainder of the structure is the same as described above regarding FIG.  2 . The apparatus  10 E according to the sixth embodiment functions in the same manner as the previous embodiments to inhibit actuation of the pretensioner  40  when the child seat  12  is present on the rear passenger seat  80 . 
     FIG. 7 illustrates an apparatus  10 F constructed in accordance with a seventh embodiment of the present invention. In FIG. 7, the child seat  12  is secured to the rear passenger seat  80  in the forward facing direction B by the seat belt webbing  30 . The antenna coil  60  is mounted in a seat back  82  of the rear passenger seat  80  and the tag  60  is secured to the upper rear portion  66  of the child seat  12 . Otherwise, the remainder of the structure is the same as described above regarding the previous embodiments. Those skilled in the art will appreciate that the circuitry in the driver/receiver circuit  52  and in the controller  50  will be selected to accommodate for the distance between the antenna coil  60  and the tag  62 . 
     The apparatus  1 OF according to the seventh embodiment functions in the same manner as the previous embodiments to inhibit actuation of the pretensioner  40  when the child seat  12  is present on the vehicle seat  80 . 
     FIG. 8 illustrates an apparatus  10 G constructed in accordance with an eighth embodiment of the present invention. In FIG. 8, the child seat  12  is secured to the rear passenger seat  80  in the forward facing direction B by the seat belt webbing  30 . As shown in FIG. 8, the antenna coil  60  is mounted in the seat back  24  of the front passenger seat  20  and faces toward the rear passenger seat  80 . The identification tag  60  is secured to the front end  64  of the child seat  12 . Otherwise, the remainder of the structure is the same as described above regarding the previous embodiments. Those skilled in the art will appreciate that the circuitry in the driver/receiver circuit  52  and in the controller  50  will be selected to accommodate for the distance between the antenna coil  60  and the tag  62 . 
     The apparatus  10 G according to the eighth embodiment functions in the same manner as the previous embodiments to inhibit actuation of the pretensioner  40  when the child seat  12  is present on the vehicle seat  80 . 
     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. For example, other types of sensing devices could be used in place of the antenna coil  60  and the tag  62 , such as RF transponders, Hall effect sensors, polarized optical sensors, and light reflectors. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.