Abstract:
To provide with a seat belt warning apparatus capable of stopping the operation of a buzzer, for example, when a passenger has moved from a rear seat to another seat, such as a front passenger&#39;s seat, and fastens the seat belt, the seat belt warning apparatus outputs a notice when the number of seats where seat belts are fastened except a driver&#39;s seat is reduced, and stops the output of the notice when the number of seats where the seat belts are fastened except the driver&#39;s seat is equal to or more than that when the notice is output.

Description:
TECHNICAL FIELD 
     The present invention relates to a seat belt warning apparatus and a seat belt warning method that give a warning when a seat belt of a vehicle is not fastened. 
     BACKGROUND ART 
     The various warning methods have been proposed which give a warning when a seat belt is not fastened (for example, see Patent Literature 1 or Patent Literature 2).  FIG. 3  is a system block diagram illustrating an example of the warning method according to the related art. As shown in  FIG. 3 , a warning apparatus according to the related art includes an ignition key switch  10  that controls the driving and stopping of an engine, a seat sensor  20  that detects whether a passenger is sitting on the seat, seat belt switches  30  that detect whether the seat belts are fastened as on/off states, a CPU (that is, a Central Processing Unit)  40 , LEDs (that is, Light Emitting Diodes)  50  that give a seat belt warning generated on the basis of a control command from the CPU  40 , and a buzzer  60  that makes a warning sound. 
     The seat belt warning apparatus having the above-mentioned structure according to the related art controls the output of a warning for the driver&#39;s seat by a combination of the start-up (IGN+10) of the engine and the seat belt switches  30 . That is, when the engine has started up and the seat belt switch  30  indicates that the seat belt is not fastened, the seat belt warning apparatus gives a warning. Meanwhile, the seat belt warning apparatus gives a warning for the front passenger&#39;s seat by a combination of the seat sensor  20  and the seat belt switches  30 , and gives a warning for the rear seats using the seat belt switches  30 . The CPU  40  periodically detects the state of the seat belt switch  30  and stores the state in a seat belt flag (register)  100  of the CPU  40 . Therefore, when any one of the seat belts of the rear seats is changed from a fastened state to an unfastened state, an LED corresponding to the rear seat is turned on to display the unfastened state of the seat belt and simultaneously, the buzzer  60  sounds to notify the unfastened state, as shown in  FIG. 4 . 
     CITATION LIST 
     
         
         [PTL 1] JP-A-63-192640 (pp. 2 to 5 and  FIG. 1 ) 
         [NPL 1] JP-A-7-186887 (pp. 2 and 3, and  FIG. 2 ) 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in the seat belt warning method according to the related art, when a passenger who is sitting on any one of the rear seats unfastens the seat belt and fastens the seat belt on the same rear seat again, it is possible to stop the operation of the buzzer  60 . However, when the passenger moves from any one of the rear seats to another rear seat and fastens the seat belt on the rear seat, or when the passenger moves from the rear seat to another seat, such as the front passenger&#39;s seat, and fastens the seat belt, the buzzer sounds for a predetermined period of time. Therefore, even though the passenger fastens the seat belt, an unnecessary warning operation is continuously performed, which is inconvenient. 
     The invention has been made in order to solve the above-mentioned problems, and an object of the invention is to provide a seat belt warning apparatus and a seat belt warning method capable of stopping an unnecessary operation of a buzzer, for example, when a passenger moves from a rear seat to another seat, such as a front passenger&#39;s seat or another rear seat, except a driver&#39;s seat and fastens a seat belt. 
     Solution to Problem 
     In order to achieve the object, according to a first aspect of the invention, a seat belt warning apparatus includes: a plurality of seat belt switches each of which is provided in each of a plurality of seats having seat belts and indicates whether each of the seat belts are fastened as on/off states; a storage unit; a control unit that stores flag groups in the storage unit, the flag group being corresponded to a plurality of successive points of time and identifying whether each of the seat belts is fastened based on on/off states of each of the plurality of seat belt switches in the storage unit; and a notification unit that performs a notifying operation under the control of the control unit, wherein the control unit compares a first flag group for each of the plurality of seat belt switches stored in the storage unit at a first point of time with a second flag group for each of the plurality of seat belt switches stored in the storage unit at a second point of time after the first point of time, and directs the notification unit to output a notice when it is determined that the number of seats where the seat belts are fastened except a driver&#39;s seat is reduced; then the control unit compares the second flag group for each of the plurality of seat belt switches stored in the storage unit at the second point of time with a third flag group for each of the plurality of seat belt switches stored in the storage unit at a third point of time after the second point of time, and directs the notification unit to stop the output of the notice when it is determined that the number of seats where the seat belts are fastened except the driver&#39;s seat is equal to or more than that when the notification unit outputs the notice. 
     According to the seat belt warning apparatus of the first aspect, the unnecessary operation of the buzzer stops, for example, when the passenger moves from the rear seat to another seat, such as the front passenger&#39;s seat, and fastens the seat belt. Therefore, this structure is suitable for safety and it is possible to give a warning to the passenger without a sense of discomfort or a sense of incongruity. 
     In addition, in order to achieve the object, according to a second aspect of the invention, a seat belt warning method includes: a notification step of outputting a notice when the number of seats where seat belts are fastened except a driver&#39;s seat is reduced; and a stopping step of stopping the output of the notice when the number of seats where the seat belts are fastened except the driver&#39;s seat is equal to or more than that when the notice is output in the notification step. 
     According to the seat belt warning method of the second aspect, the unnecessary operation of the buzzer stops, for example, when the passenger moves from the rear seat to another seat, such as the front passenger&#39;s seat, and fastens the seat belt. Therefore, this structure is suitable for safety and it is possible to give a warning to the passenger without a sense of discomfort or a sense of incongruity. 
     Advantageous Effects of Invention 
     According to the invention, the operation of the buzzer stops in the middle of the process, for example, when the passenger moves from the rear seat to another seat, such as the front passenger&#39;s seat, and fastens the seat belt. Therefore, this structure is suitable for safety and it is possible to give a warning to the passenger without a sense of discomfort or a sense of incongruity. 
     The invention has been described briefly above. The details of the invention will become apparent by reading exemplary embodiments of the invention from beginning to end with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a system block diagram illustrating a seat belt warning method according to an embodiment of the invention; 
         FIG. 2  is a flowchart illustrating the procedure of the seat belt warning method according to the embodiment of the invention; 
         FIG. 3  is a system block diagram illustrating a seat belt warning method according to the related art; and 
         FIG. 4  is a diagram schematically illustrating an example of the notification (display) of the seat belt warning method according to the related art. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a seat belt warning method according to an embodiment of the invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a system block diagram illustrating the seat belt warning method according to the embodiment of the invention. In  FIG. 1 , a seat belt warning apparatus according to the embodiment of the invention includes an ignition key switch  10  that controls the driving and stopping of an engine, a seat sensor  20  that detects whether the passenger is sitting on the seat, seat belt switches  30  that indicate whether the seat belts are fastened as an on/off state, a CPU  40 , LEDs  50  that give a seat belt warning generated on the basis of a control command from the CPU  40 , and a buzzer  60  that makes a warning sound. 
     In the seat belt warning apparatus according to the embodiment of the invention, the CPU  40  periodically detects the states of the seat belt switches  30  and stores the detected states in a seat belt flag group A (register)  100  of the CPU  40 . In  FIG. 1 , the seat belt flag group A  100  includes five flags, which correspond to the fastening states of a driver&#39;s seat belt, a front passenger&#39;s seat belt, and three rear seat belts indicated by the seat belt switches  30  of the seats from the upper side to the lower side. The CPU  40  includes a buzzer flag (register  101 ) that is set when the buzzer starts to sound and a seat belt flag group B  102  that indicates the fastening states of the seat belts when the buzzer flag  101  is set. In  FIG. 1 , the uppermost flag is omitted in the seat belt flag group B  102 , as compared to the seat belt flag group A  100 , which means that the seat belt flag group B  102  for the driver&#39;s seat is not provided. One flag of the seat belt flag group B  102  is omitted because the movement of the passenger to the driver&#39;s seat during driving is not considered. However, the seat belt flag group A  100  indicates the fastening states of the seat belts at the present time. Therefore, when a certain seat belt is not fastened, a flag “1” is set. On the other hand, when a certain seat belt is fastened, a flag “0” is set. For the buzzer flag  101 , when the buzzer  60  starts to sound, a flag “1” is set. On the other hand, when the buzzer  60  stops sounding, a flag “0” is set. 
       FIG. 2  is a flowchart illustrating the procedure of the seat belt warning method according to the embodiment of the invention. First, the CPU  40  determines whether the engine has started up on the basis of the state of the ignition key switch  10  (Step S 101 ). When it is determined that the engine has started up, the CPU  40  determines whether the buzzer flag  101  is set to “1” (Step S 102 ). 
     When the buzzer flag  101  is not set to “1” (Step S 102 ; No), the CPU  40  determines whether there is a seat having the seat belt flag group A  100  set to “1” (Step S 103 ). In this case, when there is a rear seat having the flag that has been changed from “0” to “1” among the flags of the seat belt flag group A  100 , the CPU  40  turns on the LED  50  of the seat (Step S 104 ) and simultaneously operates the buzzer  60  to sound (Step S 105 ). In addition, at that time, the CPU  40  writes information indicated by the seat belt flag group A  100  to the seat belt flag group B  102  and sets the buzzer flag  101  to “1” (Step S 106 ). When there is no rear seat having the flag set to “1” among the flags of the seat belt flag group A  100  in Step S 103 , the LED  50  is not turned on (Step S 107 ) and the buzzer flag  101  is maintained at “0”. 
     It is possible to notify the driver that the driver&#39;s seat belt or the front passenger&#39;s seat belt is not fastened using the method according to the related art using a combination of the ignition key switch  10  and the seat sensor  20 , as described above. 
     When the buzzer flag  101  is set to “1” in Step S 102 , that is, during the generation of a warning sound from the buzzer, the CPU  40  performs the following determining operation on each seat (flag). First, the CPU  40  determines whether there is a seat having the seat belt flag group B  102  set to “1” (Step S 108 ). The seat belt flag group B  102  indicates the fastening state of each seat belt (except the driver&#39;s seat belt) at the time when the buzzer starts to sound in Step S 105 . “1” is set to the flag corresponding to an unfastened seat belt and “0” is set to the flag corresponding to a fastened seat belt. 
     When there is a flag set to “1” among the flags of the seat belt flag group B  102 , the CPU  40  determines whether the flag of the seat belt flag group A  100  corresponding to the seat having a flag set to “1” in the seat belt flag group B  102  is reset to “0” (Step S 109 ). When the flag of a certain seat in the seat belt flag group B  102  is set to “1”, but the flag of the seat in the seat belt flag group A  100  at the present time is set to “0”, that is, the seat belt has changed from an unfastened state to a fastened state, it is considered that the passenger has refastened the seat belt. Therefore, when the flag of the seat in the seat belt flag group A  100  is reset to “0” (Step S 109 ; Yes), the CPU  40  stops the operation of the buzzer  60  (Step S 110 ), and resets the buzzer flag  101  to “0” (Step S 111 ). 
     When the flag of the seat in the seat belt flag group B  102  is set to “1” and the flag of the seat in the seat belt flag group A  100  is not reset to “0” (Step S 109 ; No), the CPU  40  determines whether there is a flag changed from “1” to “0” among the flags of the other seats in the seat belt flag group A  100 , that is, whether there is a seat belt changed from an unfastened state to a fastened state (Step S 112 ). For example, when the front passenger&#39;s seat belt is changed from an unfastened state to a fastened state after one of the rear seat belts is not fastened, it is considered that the passenger has moved from the rear seat to the front passenger&#39;s seat. In this case, it is determined that all passengers have fastened seat belts. Therefore, it is considered that requirements to give a warning using the buzzer  60  are reduced. Even when whether there is a flag changed from “1” to “0” among the flags of the other seats in the seat belt flag group A  100 , that is, a change from the unfastened state to the fastened state is confirmed (Step S 112 ; Yes), the CPU  40  proceeds to Step S 110  to stop the operation of the buzzer  60  and resets the buzzer flag  101  to “0” (Step S 111 ). 
     The main point of the process in Steps S 109  and S 112  is that the number of seats where the seat belts are fastened before the buzzer  60  sounds is compared with the number of seats where the seat belts are fastened after the buzzer  60  sounds. As another processing method, the number of flags set to “0” in the seat belt flag group A  100  (however, except the flag corresponding to the driver&#39;s seat) may be compared with the number of flags set to “0” in the seat belt flag group B  102 . Conversely, the number of flags set to “1” in the seat belt flag group A  100  (however, except the flag corresponding to the driver&#39;s seat) may be compared with the number of flags set to “1” in the seat belt flag group B  102 . In addition, in the embodiment of the invention, the CPU  40  detects a variation in the flags in the seat belt flag groups A and B with reference to the seat belt flag groups A and B stored in the register. However, the invention is not limited only to the structure in which the CPU detects the fastening states of the seat belts on the basis of the stored seat belt flag groups A and B. The CPU  40  may monitor the on or off states of the seat belt switches  30  in real time. When detecting that one of the seat belt switches  30  has changed from an on state (the state in which the seat belt is fastened) to an off state (the state in which the seat belt is unfastened), the CPU  40  may direct the notification unit to output a notice. Then, when detecting that any one of the seat belt switches  30  has changed from an off state to an on state, the CPU  40  may direct the notification unit to stop the output of the notice. 
     However, in this embodiment, only the operation of the buzzer stops, but the display of a notice using the LEDs that are considered not to give a sense of incongruity or a sense of discomfort is continuously performed. However, in this embodiment, the LED  50  is used as the notification unit using display, but the invention is not limited thereto. For example, an LCD or an organic EL device may be used for display. 
     The process from Step S 101  to Step S 112  is performed with a predetermined period. In addition, the process of the seat belt warning method is performed by executing a predetermined program with the CPU  40 . 
     In the embodiment of the invention, when one of the seat belts switches  30  is changed from an on state to an off state and then any one of the seat belt switches  30  is turned on, the notifying operation stops. However, the notifying operation also stops when one of the seat belt switches  30  is changed from an on state to an off state and then a plurality of seat belt switches  30  is turned on. In particular, this case occurs when an additional passenger boards the vehicle. In this case, it is possible to stop the unnecessary operation of the buzzer. 
     The invention has been described in detail above with reference to a specific embodiment, but it will be understood by those skilled in the art that various modifications and changes of the invention can be made without departing from the scope and sprit of the invention. 
     Priority is claimed on Japanese Patent Application No. 2008-161595, filed on Jun. 20, 2008, the content of which is incorporated herein by reference. 
     REFERENCE SIGNS LIST 
     
         
         
           
               10 : IGNITION KEY SWITCH 
               20 : SEAT SENSOR 
               30 : SEAT BELT SWITCH 
               40 : CPU 
               50 : LED 
               60 : BUZZER 
               100 : SEAT BELT FLAG GROUP A 
               101 : BUZZER FLAG 
               102 : SEAT BELT FLAG GROUP B