Abstract:
A car seat is provided with a detector for detecting whether a seat belt is buckled or unbuckled and a deformation mechanism for partial deformation of the car seat. The partial deformation is held when an ignition switch of a car engine is switched on and the detector detects the seat belt is unbuckled. The partial deformation is canceled when the detector detects the seat belt is buckled. The deformation mechanism displaces at least one element out of a headrest, a seatback and a seat cushion of the car seat so as to partially deform the car seat.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a car seat with a seat belt warning mechanism for giving warning to an occupant when the seat belt is unbuckled. 
   2. Description of the Related Art 
   A vehicle is usually provided with a seat belt warning device such as a warning lamp for giving warning an occupant to buckle a seat belt. The occupant often misses the warning lamp and fails to buckle the seat belt because the warning lamp is located in an obscure place. 
   Japanese Patent Application Laid-Open H10-236279 discloses a warning indicator located in a noticeable place such as on a dashboard or on a roof. Such locations are noticeable even from an outside of the vehicle thereby a people around the vehicle notice that the occupant fails to buckle the seat belt. The occupant is forced to buckle the seat belt. 
   SUMMARY OF THE INVENTION 
   According to the related art, if the indicator is located outside of the vehicle, the inside occupant hardly notices the warning. In contrast, if the indicator is located inside of the vehicle, the indicator is not enough noticeable. 
   The present invention is intended for providing a car seat with a warning device to effectively give warning to an occupant when the seat belt is not buckled. 
   According to the present invention, a car seat is provided with a detector for detecting whether a seat belt is buckled or unbuckled and a deformation mechanism for partial deformation of the car seat. The partial deformation is held when an ignition switch of a car engine is switched on and the detector detects the seat belt is unbuckled. The partial deformation is canceled when the detector detects the seat belt is buckled. The deformation mechanism displaces at least one element out of a headrest, a seatback and a seat cushion of the car seat so as to partially deform the car seat. 
   The car seat is partially deformed by the deformation mechanism so that an occupant has to sit on the car seat in an irregular position as long as he does not buckle the seat belt. He has to buckle the seat belt to get a regular position. Thus the car seat of the present invention effectively gives warning to the occupant. 
   In contrast, in a case where the occupant is forced to urgently start the car, he can switch on the ignition switch and start the car without buckling the seat belt, if he stands the irregular position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective, partly transparent, view of a certain part of a car seat according to a first embodiment of the present invention; 
       FIG. 2  is a top plan view of a stopper mechanism and a stay holder of the car seat of the first embodiment; 
       FIG. 3  is a perspective view of a certain part of the car seat showing an operation of the stopper mechanism; 
       FIG. 4  is a perspective view of a certain part of a seat belt and a buckle according to a first embodiment of the present invention; 
       FIG. 5  is a circuit diagram of an operation of the stopper mechanism; 
       FIG. 6  is a perspective, partly transparent, view of a headrest according to a second embodiment of the present invention; 
       FIG. 7A  is a side view of the headrest according to the second embodiment showing a regular position thereof; 
       FIG. 7B  is a side view of the headrest according to the second embodiment showing a tilted position; 
       FIG. 8  is a flowchart describing a control of a tilt mechanism of the headrest; 
       FIG. 9  is a side, partly transparent, view of a car seat according to a third embodiment of the present invention; 
       FIG. 10  is a perspective view of a cushion lifting mechanism according to a third embodiment of the present invention; 
       FIG. 11A  is a side, partly transparent, view of a certain part of a car seat according to a fourth embodiment of the present invention, showing a stopper mechanism holding a cushion seat to be lifted; and 
       FIG. 11B  is a perspective, partly transparent, view of a certain part of the car seat showing the stopper mechanism canceling holding. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A first embodiment of the present invention will be described hereinafter with reference to  FIGS. 1-5 . 
   A car seat  1  of the first embodiment of the present invention is provided with a buckle switch  3  shown in  FIG. 4 , an ignition switch  4  shown in  FIG. 5 and a  headrest forward tilting mechanism  10  shown in FIG.  1 . The headrest forward tilting mechanism  10  is a deformation means for displacing a headrest  5  so as to give warning to an occupant (not shown in  FIGS. 1-4 ) when the occupant does not buckle the seat belt. The buckle switch  3  is a detection means for detecting whether a seat belt  2  is buckled. When the buckle switch  3  detects that the seat belt  2  is not buckled though the occupant sits on the car seat  1  in a case where the ignition switch  4  is ON, the headrest forward tilting mechanism  10  presses the occupant as the warning. 
   The headrest forward tilting mechanism  10  is provided with a support portion  11  for supporting the headrest  5 , a spring  12  for applying a force to the headrest  5  to be tilted forward and a stopper mechanism  13 . The stopper mechanism  13  holds the headrest  5  to be a regular position shown in  FIG. 1  in a normal state and allows the headrest  5  to be tilted forward when the seat belt  2  is not buckled. 
   The support portion  11  is provided with a rotation shaft  11 A rotatably supported by a pair of seat frames  6   a  of a seatback  6 , a pair of stay holder  11 B fixed to the rotation shaft  11 A and a pair of stays  5   a  respectively fixed to the stay holder  11 B. A lower end of the headrest  5  is detachably attached to the stays  5   a.    
   The spring  12  is fitted around the rotation shaft  11 A. One end  12   a  of the spring  12  is latched to the stay holder  11 B and the other end  12   b  is latched to the seat frame  6   a  in a state that the spring  12  applies a force to the headrest  5  so as to be tilted forward. 
   The stopper mechanism  13  essentially consists of a stopper  13 A shaped bar-like, a solenoid  13 B for driving the stopper  13 A so as to be ejected and retracted and a spring  13 C for applying a force to the stopper  13 A so as to be ejected as shown in FIG.  2 . The solenoid  13 B retracts the stopper  13 A against the force of spring  12  when current is sent to the solenoid  13 B, and the stopper  13 A is ejected by the force of the spring  13  when the current is switched off. 
   An end portion of the stopper  13 A is engaged with a rear side of the stay holder  13 B so as to hold the stay holder  11 B at a regular position when the stopper  13 A is ejected. The end portion of the stopper  13 A is separated from the stay holder  13 B so that the headrest  5  is tilted forward with the rotation shaft  11 A as an axis as shown in  FIG. 3  when the stopper  13 A is retracted. 
   A slanted surface  13 Aa is formed at a rear side of the end portion of the stopper  13 A. When a front side of the stay holder  11 B abuts the slanted surface  13 Aa, the stay holder  11 B slides on the slanted surface  13 Aa so as to retract the stopper  13 A. When the stay holder  11 B is further pressed to the slanted surface  13 Aa, the stay holder  11 B goes over the stopper  13 A and the stopper  13 A is ejected again as shown in FIG.  2 . Thereby, when the headrest  5  is tilted forward and the stopper  13 A is ejected as shown in  FIG. 3 , pressing the headrest  5  rearward results the stopper  13 A to be retracted and ejected again so that the headrest  5  moves to the regular position and is held by the stopper  13 A. 
   The buckle switch  3  is provided for detecting whether the seat belt  2  is buckled or unbuckled. The buckle switch  3  shown in  FIG. 4  is operated by insertion and extraction of a tongue  2 A of the seat belt  2  to a buckle  2 B. The buckle switch  3  is ON when the tongue  2 A is extracted from the buckle  2 B, and the buckle switch  3  is OFF when the tongue  2 A is inserted. 
   The buckle switch  3  is connected with a battery  7  and the ignition switch  4  in series. When the ignition switch  4  is switched ON though the seat belt  2  is not buckled, both the ignition switch  4  and the buckle switch  3  are switched ON so that current is applied to the solenoid  13 B of the stopper mechanism  13  so as to retract the stopper  13 A. 
   In contrast, when the seat belt  2  is buckled, if the ignition switch  4  is switched ON, the buckle switch  3  is OFF though the ignition switch is ON. Thereby the current to the solenoid  13 B is switched off so as to eject the stopper  13 A. 
   According to the car seat  1  of the aforementioned first embodiment, if an occupant switches the ignition switch  4  ON though the seat belt  2  is not buckled, the headrest  5  is tilted forward so as to give warning to the occupant. 
   He has to buckle the seat belt  2  to get a regular position. When he buckles the seat belt  2  so that the buckle switch  3  is OFF and the stopper  13 A is ejected, he can press the headrest  5  rearward with his head so that the headrest  5  is restored to the regular position. 
   An application of the car seat  1  of the first embodiment is not limited to a driver&#39;s seat. The car seat  1  can be applied to either a front passenger seat or rear seats. 
   According to the first embodiment of the present invention, the car seat  1  effectively gives warning to the occupant to buckle the seat belt  2  though the warning is not so severe. In a case where the occupant is forced to urgently start the car, he can start the car without buckling the seat belt  2 , if he stands the irregular position. 
   Furthermore, the headrest forward tilting mechanism  10  is simply composed, thereby the car seat  1  needs not have a complex structure. 
   A second embodiment of the present invention will be described hereinafter with reference to  FIGS. 6-8 . In the following description, the same elements as the above first embodiment are referenced with the same numerals and the detailed descriptions are omitted. Mainly differences are described below. 
   A car seat  1   c  of the second embodiment is provided with a support portion  100  for supporting the headrest  5 , a spring  101  for applying a force to the headrest  5  via the support portion  100  and a stopper mechanism  102 . Differently from the aforementioned first embodiment, the applied force tilts the headrest  5  backward. 
   Meanwhile, in the description of the second embodiment, “the headrest  5  is tilted backward around the support portion  100 ” means “a lower half of the headrest  5  is projected forward”. 
   A core member  103  is formed in an inverted U-letter shape and therefore provided with a pair of vertical portions  103   a  and a horizontal portion  103   b.  A cylinder portion  100   a  of the support portion  100 , to which a flame  104  is integrally fixed in a hanging manner, is rotatably fit around the horizontal portion  103   b  and the spring  101  is inserted therebetween so as to give the force to the support portion  100 . A stopper mechanism  102  is fixed to one of the vertical portions  103   a  and disposed in the vicinity of the flame  104 . The support portion  100 , the spring  101 , the stopper mechanism  102  and the flame  104  are housed in the headrest  5 . The pair of vertical portions  103   a  of the core member  103  are respectively inserted into a pair of holders  105  which are fixed in the seat frame  6   a.  An exterior material  105   b  and a cushion material  5   c  of the headrest  5  are provided with a pair of slits  106  so as to allow the vertical portions  103   a  passing therethrough. Thereby the headrest  5  can be tilted backward. 
   The flame  104  is further provided with a pair of holding portions  104   a  formed in a half cylinder shape. The holding portions  104   a  are formed so as to respectively fit with the vertical portion  103   a  and function as a stopper for restricting a rotation of the headrest  5 . 
   The stopper mechanism  102  is provided with a stopper  102   b  which is retractable into the stopper mechanism  102  and urged so as to be ejected by means of a spring (not shown) installed therein. 
   The stopper mechanism  102  is further provided with a solenoid (not shown) installed therein. In a case where current is applied on the solenoid, the stopper  102   b  is retracted against a force of the spring. In a case where the current is switched off, the stopper  102   b  is ejected. When ejected from the stopper mechanism  102 , the stopper  102   b  is engaged with the flame  104  so that the headrest  5  is prevented from tilting backward. When retracted into the stopper mechanism  102 , the headrest  5  is free from the stopper  102   b  so as to tilt backward. 
   The current is switched by means of the buckle switch  3  and the ignition switch  4 , like as the aforementioned first embodiment. When the ignition switch  4  is switched ON though the seat belt  2  is not buckled, both the ignition switch  4  and the buckle switch  3  are switched ON so that current is applied to the solenoid of the stopper mechanism  102  so as to retract the stopper  102   b.  In contrast, when the seat belt  2  is buckled, if the ignition switch  4  is switched ON, the buckle switch  3  is OFF though the ignition switch is ON. Thereby the current to the solenoid is switched off so as to eject the stopper  102   b.    
   In a steady state, the stopper  102   b  is engaged with the flame  104  so that the headrest  5  is prevented from tilting backward as shown in FIG.  7 A. In a case where the ignition switch  4  is switched ON though the seat belt  2  is not buckled, the stopper  102   b  is retracted so that the headrest  5  is tilted backward as shown in FIG.  7 B. 
   Of course, in a case where the headrest  5  is tilted backward though the seat belt  2  is buckled, the headrest  5  can be back to a regular position as shown in  FIG. 7B  by means of pressing the headrest  5  backward. The flame  104  can easily overcome the stopper  102   b  against the force applied by the spring. 
   A tilt angle θ of the headrest  5  is restricted by abutment of the core member  103  with a back end of the slit  106  as shown in FIG.  7 B. 
   The control of the stopper mechanism  102  can be schematically shown as a flow chart of FIG.  8 . Provided that the ignition switch  4  is ON (judged at a step S 1 ), a parking switch is OFF (judged at a step S 2 ) and the buckle switch  3  is ON (judged at a step S 3 ) caused by not buckling the seat belt  2 , the stopper mechanism  102  is canceled so as to tilt the headrest  5  backward at a step S 4 . Then the occupant is given warning. 
   Meanwhile, in a case where the ignition switch  4  is judged to be OFF at the step S 1 , the control is terminated. In a case where the parking switch is judged to be ON at the step S 2  or the buckle switch  3  is judged to be OFF at the step S 3 , the control is made back to the step S 1  and this series of the steps are re-achieved. 
   As will be understood from the above description, the car seat  1   c  of the second embodiment effectively gives warning to the occupant to buckle the seat belt  2  though the warning is not severe, similarly to the first embodiment. The occupant can press the headrest  5  with his head so that the headrest  5  is restored to the regular position. Of course, in a case where the occupant is forced to urgently start the car, he can start the car without buckling the seatbelt  2 , if he stands the irregular position. 
   Furthermore, the functional members such as the support portion  100 , the spring  101  and the stopper mechanism  102  are housed in the headrest  5 . Thereby the composition of the headrest  5  does not influence the structure of the seatback  6 . The present embodiment of the present invention can be applied to a commonly structured seatback. 
   Furthermore, the headrest  5  can be simply composed and needs not have a complex structure. 
   A third embodiment of the present invention will be described hereinafter with reference to  FIGS. 9 and 10 . In the following description, the same elements as the above first embodiment are referenced with the same numerals and the detailed descriptions are omitted. Mainly differences are described below. 
   A car seat  1   a  of the third embodiment is provided with a cushion lifting mechanism  20  for lifting a front portion of a seat cushion  8  as a deformation means for displacing a seat cushion  8  so as to give warning to an occupant as shown in  FIGS. 9 and 10 . 
   The cushion lifting mechanism  20  is provided with a pair of swinging members  21  housed in the seat cushion  8 , springs  22  for respectively giving an upward force to the swinging members  21  and a stopper mechanism  23 . The swinging members  21  are rotatably supported on a pan frame  8   a  so that a front end portion  21   a  thereof is allowed to be swing up and down. The stopper mechanism  23  holds the swinging members  21  in a lower position when the seat belt is not buckled. The stopper mechanism  23  cancels holding and allows the swinging members  21  to swing upward when the seat belt is buckled. 
   The swinging members  21  are formed in pair and symmetrically provided at both sides in the seat cushion  8 . Rear end portions  21   b  thereof are rotatably supported by brackets  24  fixed to the pan frame  8   a  with pins  25  so that the swinging members  21  can swing up and down. The pair of swinging members  21  are connected by a connection bar  21   c  at the front end portions  21   a.    
   The swinging members  21  can swing upward as shown in full lines in  FIG. 9  so that the front end portion of the seat cushion  8  is lifted and femoral regions of the occupant is pressed upward. In contrast, the swinging members  21  can also swing downward as shown in broken lines in  FIG. 9  so that the front end portion of the seat cushion  8  can be pushed down and he can get a normal seating position. 
   The brackets  24  are fixed to the pan frame  8   a  via respective flanges  24   a  and each of the flanges  24   a  is provided with a lower latch  24   b  as shown in FIG.  10 . Each of the rear end portions  21   b  is further extended rearward and an end thereof is provided with an upper latch  21   d.  The springs  22  are respectively latched between the lower latches  24   b  and the upper latches  21   d  so as to apply a force to the swinging members  21 , thereby the front end portions  21   a  of the swinging members  21  are urged to swing upward. 
   The stopper mechanism  23  essentially consists of a stopper  23 A shaped bar-like and a solenoid  23 B for driving the stopper  23 A so as to be ejected and retracted. The solenoid  23 B retracts the stopper  23 A when current is switched ON, and ejects the stopper  23 A when the current is switched OFF. 
   An end portion of the stopper  23 A is engaged with a lower side of the swinging member  21  so as to hold the swinging members  21  at an upper position when the stopper  23 A is ejected. The swinging members  21  can swing downward as shown in  FIG. 9  when the end portion of the stopper  23 A is retracted. 
   A vertical width of the swinging member  21  accommodated with the stopper  23 A is broader than a swinging range thereof so that the stopper  23 A abuts the swinging member  21  so as not to be ejected when the swinging member  21  swings downward. 
   A buckle switch of the third embodiment (not shown in the drawings) is also operated by the seat belt. The buckle switch is ON when the seat belt is buckled, though the buckle switch is OFF when the seat belt is unbuckled. 
   According to the car seat  1   a  of the third embodiment, the front portion of the seat cushion  8  is lifted by the force of the spring  22  as shown in full lines in FIG.  9  and the stopper  23 A is engaged with the lower side of the swinging member  21  before the occupant takes the seat. 
   If the occupant might switch the ignition switch ON though the seat belt was not buckled, the stopper  23 A was kept engaging with the lower side of the swinging member  21  so as to give warning to the occupant. 
   He has to buckle the seat belt to get a normal seating position. When he buckles the seat belt so that the buckle switch is OFF and the stopper  23 A is retracted, he can press the seat cushion  8  downward with his femoral regions so that the seat cushion  8  recovers to a regular position. 
   A fourth embodiment of the present invention will be described hereinafter with reference to  FIGS. 11A and 11B . In the following description, the same elements as the above first through third embodiments are referenced with the same numerals and the detailed descriptions are omitted. Mainly differences are described below. 
   A car seat  1   b  of the fourth embodiment is provided with a cushion lifting mechanism  30 , a linkage  31 , a spring  32  and a stopper mechanism  33  as shown in  FIGS. 11A and 11B . The cushion lifting mechanism  30  is provided for lifting a front portion of a seat cushion  8  as a deformation means for displacing the seat cushion  8  so as to give warning to an occupant. The linkage  31  is provided between a front portion of the seat cushion  8  and a lower cover  9  so as to able to shrink and expand. The spring  32  is provided for applying an upward force to the seat cushion  8 . The stopper mechanism  33  holds the linkage  31  to expand when the seat belt is not buckled and cancels holding the linkage  31  so as to shrink when the seat belt is buckled. 
   The linkage  31  is provided with a first link  31 A rotatably fixed to a lower side of the seat cushion  8  and a second link  31 B rotatably fixed to the lower cover  9  via a bracket  34   a,  and the first link  31 A and the second link  31 B is rotatably connected at a node so that the linkage  31  can shrink and expand. 
   The spring  32  is put between the lower side of the seat cushion  8  and the lower cover  9  so as to be compressed. The spring  32  gives an upward force to the front portion of the seat cushion  8 . 
   The stopper mechanism  33  has a similar constitution as the stopper mechanism  23  of the third embodiment. The stopper mechanism  33  essentially consists of a stopper  33 A and a solenoid  33 B. The solenoid  33 B retracts the stopper  33 A when current is switched ON, and ejects the stopper  33 A when the current is switched OFF. 
   An end portion of the stopper  33 A is engaged with an outer side of the node of the first link  31 A and the second link  31 B to hold the linkage  31  to expand as shown in  FIG. 11A  when the stopper  33 A is ejected. The linkage  31  can shrink so that the seat cushion  9  can be pressed down when the stopper  33 A is retracted. 
   The stopper  33 A is provided so as not to engaged with an inner side of the node of the first link  31 A and the second link  31 B when the linkage  31  shrinks. 
   A buckle switch of the fourth embodiment (not shown in the drawings) is also operated by the seat belt in the same way as the third embodiment. 
   According to the car seat  1   b  of the fourth embodiment, the front portion of the seat cushion  8  is lifted by the force of the spring  32  as shown in FIG.  11 A and the stopper  33 A is engaged with the outer side of the node of the first link  31 A and the second link  31 B to hold the linkage  31  to expand before the occupant takes the seat. 
   If the occupant might switch the ignition switch ON though the seat belt was not buckled, the stopper  33 A was kept engaging with the outer side of the node so as to give warning to the occupant. 
   He has to buckle the seat belt to get a normal seating position. When he buckles the seat belt so that the buckle switch is OFF and the stopper  33 A is retracted, he can press the seat cushion  8  downward with his femoral regions so that the seat cushion  8  recovers to a regular position. 
   The contents of Japanese Patent Application No.2002-350286 (filed on Dec. 2, 2002) are incorporated herein by reference in its entirety. 
   Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art, in light of the above teachings. For example, the warning means is not limited as the headrest forward tilting mechanism  10  or the cushion cushion lifting mechanisms  20 ,  30 . Any local pressure means for pressing an occupant&#39;s back and such are available.