Abstract:
A sensing device for a safety belt comprising a tightening unit having a fastening plate; a pulling force recording unit fastening seat of the safety belt; an impact status recording unit; a record indication unit; and a cartridge housing containing these units therein, wherein the pulling force recording unit comprises a clipping frame containing a fastening rim with one end protruded out therefore, and an engaging element capable of changing the resistance value when a pulling force is exerted, the impact status recording unit comprises a pendulum, on a circuit board, which changes the resistance value of the circuit board by the swinging of the pendulum, and the fastening status recording unit comprises an enumerating sensing switch, and the electrical signal and resistance of the units are transferred to the record indication unit.

Description:
This application claims the benefit of priority of Taiwan app. ser. no. 088106974, filed Apr. 29, 1999. 
   BACKGROUND OF THE INVENTION 
   a) Technical Field of the Invention 
   The present invention relates to a sensing device for a safety belt, and in particular, to a sensing device which can be connected to the safety belt to sense and to record the pulling force of the safety belt caused by an impact, direction of the impact and the impact force, so as to provide a status proof of fastening the safety belt. 
   b) Description of the Prior Art 
   As shown in  FIG. 1 , the conventional safety belt includes a fastening plate  1  and a fastening seat  2 . When the fastening plate  1  is inserted into the seat  2 , the safety belt can provide a mere function of holding the user. The conventional belt does not have a sensing function. It is very common for the driver or the passenger to forget to put on the safety belt when he gets into the car. When the car hits a big object, or a great impact has occurred to the car, the driver or the passengers may be hurt if the belt has not been put on properly. 
   In a school bus carrying a number of school children, it is possible that some school boys play with the belt as if the belt is a toy by frequently releasing and fastening on the safety belt. It may not have sufficient number of guardians in the school bus to look after the children. Therefore, the children without putting on the belt may be hurt if an accident or an impact is caused to the bus. This is because the conventional belt does not have a sensing device to provide a warning signal to the user. 
   SUMMARY OF THE INVENTION 
   Therefore, it is an object of the present invention to provide a sensing device for a safety belt, wherein the sensing device can be connected to a safety belt and the sensing device is provided with a enumerating recording switch to provide a enumerating recording signal with respect to seat belt fastening. 
   Another object of the present invention is to provide a sensing device for a safety belt, wherein the sensing device can be connected to a signal processor to process the signals transmitted from the sensing device. 
   Yet another object of the present invention is to provide a sensing device for a safety belt, wherein a pulling force recording unit is mounted such that the unit can precisely record the instantaneous pulling force of the safety belt when an impact to the car is occurred. 
   It is another object of the present invention to provide a sensing device for a safety belt, wherein an impact status recording unit is provided to the sensing device such that the impact force and the direction of impact can be precisely recorded if an impact to the car is occurred. 
   Yet another object of the present invention is to provide a sensing device for a safety belt, wherein the sensing device is compact and portable. 
   Another object of the present invention is to provide a sensing device for a safety belt, wherein the sensing device can be mounted together with the fastening seat of any conventional safety belt. 
   Additional advantages of this invention will become apparent from the description which follows, taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of a conventional safety belt fastener. 
       FIG. 2  is a schematic perspective view of a sensing device to be mounted to a safety belt in accordance with the present invention. 
       FIG. 3  is a perspective view of the sensing device for a safety belt in accordance with the present invention. 
       FIG. 4  is a perspective exploded view of the sensing device in accordance with the present invention. 
       FIG. 5  is a perspective exploded view of an engaging element of  FIG. 4  in accordance with the present invention. 
       FIG. 6  is a perspective exploded view of the sensing device for a safety belt, indicating the recording indication unit, in accordance with the present invention. 
       FIG. 7  is a perspective exploded view of the sensing device for a safety belt, indicating the pulling force recording unit of the present invention. 
       FIG. 8  is a perspective exploded view of the pulling force recording unit of  FIG. 7  of the present invention. 
       FIG. 9  is a perspective exploded view of the fastening plate of  FIG. 8  of the present invention. 
       FIG. 10  is a perspective exploded view of the pulling force resistance circuit board of  FIG. 8  of the present invention. 
       FIG. 11  is a perspective view of the elastic mounting unit of  FIG. 8  of the present invention. 
       FIG. 12  is a perspective exploded view of the impact recording unit of  FIG. 7  of the present invention. 
       FIG. 13  is a schematic view illustrating the movement of the pendulum of  FIG. 12  of the present invention. 
       FIG. 14  is a circuit diagram of the enumerating of fastening the present invention. 
       FIG. 15  is a circuit diagram of impact time memory of the sensing device of the present invention. 
       FIG. 16  is a circuit diagram of the pulling force indication of the sensing device of the present invention. 
       FIG. 17  is a circuit diagram of the impact force indication of the sensing device of the present invention. 
       FIG. 18  is a perspective view of a signal processor in combination with the sensing device mounted with the safety belt. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  illustrates a conventional safety belt. In application, the belt provides a pulling protection to the wearer. The conventional safety belt does not provide a sensing device to record the status of application of the belt. 
   Referring to  FIG. 2 , there is shown the sensing device to be mounted to the safety belt. As shown in  FIG. 3 , the sensing device  3  has one protruded fastening loop  6  insertable into a mounting slot  91  of the fastening seat  2  of the safety belt. One edge of the sensing device  3  is provided with a fastening recess  92 . A releasing button  25  is mounted on one lateral face of the sensing device  3  for the releasing of the fastening plate  1  of the safety belt from the sensing device  3 . On the opposite lateral side of the sensing device  3 , a stencil plate  26  with function indication is provided. Along one edge of the sensing device  3 , a signal socket  30  is mounted. 
   Referring to  FIG. 4 , there is shown a perspective view of the sensing device of the present invention. The sensing device  3  comprises a tightening unit  100  for mounting with the fastening plate  1  of the safety belt; a pulling force recording unit  200  for mounting to the fastening seat  2  of the safety belt; an impact status recording unit  300 ; a fastening status recording unit  400 ; a record indication unit  500 . 
   The tightening unit  100  comprises an engaging element  101  and a releasing button  25 . The engaging element  101  is mounted adjacent to the lateral face close to the releasing button  25  for engaging with the fastening plate  1  of the safety belt. As shown in  FIG. 5 , the engaging element  101  comprises a fastening board  28  having one end mounted with a rotating shaft  29  having a twisting spring  82 . The reverse twisting of the spring  82  causes the fastening board  28  to produce an engaging action. 
     FIG. 6  is a perspective exploded view of the sensing device  3 . On an indication circuit board  72 , there are mounted with two timing indication circuits  102 ,  103 , a time adjusting button  104 , an impact indication light  105 , at least one battery  106 , a plurality of ICs  107 , and a signal line connector  108 . At normal circumstance, the two timing indication circuits  102 ,  103  record time simultaneously and are controlled by the time adjusting button  104 . If an impact has occurred, one timing indication circuit  102  receives an impact signal from other units, such as units  200 ,  300 . At this moment, time recording stops so as to indicate the impact time. The other time indication circuit shall not be affected but continues its time recording. 
   At an appropriate position on the board  72 , a plurality of screws  73  are employed to fasten the board  72  together with the pulling force recording unit  200 . The screws  73  pass through the screw holes  74  and shaft pads  75  prior to mounting the board  72  with the unit  200 . 
   As shown in  FIGS. 7 ,  9 ,  10 ,  11 , a clipping frame  10 , and a mounting frame  14  contain a fastening loop  6  protruded from one end of the frame  10 , and an elastic mounting unit  109 . A number recording switch  41  is provided on the mounting frame  14 . This switch  41  is connected to the signal socket  30  so as to transmit an alarming signal if the belt has not been fastened and to transmit the enumerating of fastening the belt signal. 
   The elastic mounting unit  109  comprises an elongated plate  110 , a circuit board  4  having the function of converting the pulling force into electrical resistance, a plurality of compression springs  5 , and a stopping gear assembly  8 . The stopping gear assembly  8  has a gearing element  112  mounted with a peg  7  having been inserted with a twisting spring  82 . The gearing element  112  faces a positioning ratchet  9 . The two ends of the peg  7  are mounted perpendicularly with the clipping frame  10  and the mounting frame  14 . The gearing element  112  is positioned to the ratchet  9  when the elongated plate  110  is pulled out. The two ends of the spring  5  respectively urge the spring support  93  and the resisting plate  11 , such that the elongated plate  110  is positioned in between the clipping frame  10  and the mounting frame  14 . When at great impact, the impact force produces a greater displacement force than the spring  5  the support  93  presses the spring  5  such that the elongated plate  110  moves slightly. The circuit board  4  is mounted adjacent to the elongated plate  110 . 
   As shown in  FIG. 10 , a conductive layer  50 , a plurality of variable electrical resistance layers  51 , two parallel high impact conductive layers  52 ,  53  and a signal output connector  33  are mounted on the board  4 . The variable resistance layer  51  is parallel to the conductive layer  50 . These layers  50 ,  51  can contact with the spring plate  34  and the conductive layers  52 ,  53  are further away from the spring plates  34 ,  35 . 
   When the displacement of the elongated plate  110  is great, the spring plate  35  touches the conductive layers  52 ,  53  to output a strong impact signal. These layers  50 ,  51 ,  52 ,  53  transmit the conductive signals, via the signal output connector  33 , to the record indication unit  500 . 
   As shown in  FIG. 11 , if an impact has occurred, the fastening loop  6  is pulled out to a distance which has corresponding layers  50 ,  51 ,  52 ,  53  and are conductive and output a corresponding electrical resistance value. 
   As shown in the figure, the impact status record unit  300  is connected to the elastic mounting unit  109  which is connected to the record indication unit  500 . As shown in  FIG. 12 , the unit  500  has a circuit board  16  comprises a pendulum  96  having a heavy weight body  18  at one end. The pendulum  96  is made from a conductive material. At the end closer to the heavy weight body  18 , a fastener body  114  having a pressing tip  59  to press the circuit board  16  is provided. At the lateral side of the fastener body  114 , a pressing contact  58  is provided. A thin spring  19  is mounted across the edge of the board  16 . On the arc-shaped path formed by the swinging movement of the pressing tip  59 , a plurality of engaging recesses  61  is formed on the board  16 . On the arc-shaped path formed by the swinging of the pressing contact  58 , a resistance membrane  60  is formed on the board  16 . A pair of mounting hooks  17  are mounted on the board  16  to engage to one end of the thin spring  19 . The other end of the spring  19  is connected to the pendulum  96 , such that the board  16  is connected to the pendulum  96  and formed a conductive circuit, which is connected, together with the circuit of the resistance membrane  60 , to the connecting point of the record indication unit  500 . Thus, after the pendulum  96  is mounted to the circuit board  16  and by means of the balancing effect of the two thin springs  19 , the pendulum  96  is maintained at the center. Thus, the pendulum  96  is used as a switch by means of sensing vibration moment. 
   Referring to  FIG. 13 , a schematic view illustrating the movement of the pendulum. When an accident is occurred, the instantaneous force produced by the impact is greater than the pulling force of the thin spring  19  such that the pendulum  96  swings to a position with minimum kinetic energy. The pressing tip  59  is engaged with the engaging recess  61  such that the pendulum  96  is deadly engaged and fixed. At the same time, the pressing contact  58  slides to contact with the resistance membrane  60  at the corresponding position such that the resistance value at that position is transmitted out. The impact force, and direction of impact can be converted into a corresponding resistance value which can be electrically analyzed and the indication of impact is shown in pound. 
     FIGS. 14 to 17  are circuit diagrams, and the structure, and the principle are corresponding to the above described recording indication unit  500 . 
   In application of the present invention, as shown in  FIG. 18 , the signal socket  30  of the sensing device is connected with a signal line  83  to the signal processor  90  for signal processing. The signal processor  90  possesses the ability to determine signals such as unfastening of safety belt, in appropriateness of belt-releasing, so that a signal or an alarming sound is provided. 
   Many changes, modifications, variations and uses of the present application will become apparent to those skilled in the art after considering this specification and the accompanying drawing which disclose the preferred embodiment thereof. All such changes, modification, variations and other uses which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited by the claims which follow.