Abstract:
A plurality of passenger protecting devices, such as airbags or seatbelt pretensioners, are actuated by a controller upon detection of a collision. According to types of collision, particular passenger protecting devices are selected and actuated. The controller includes a main circuit and a safeguard circuit for actuating the passenger protecting devices, and the selected passenger protecting devices are actuated when both circuits generate signals for actuating the passenger protecting device. The passenger protecting devices to be selected according to types of collision are pre-programmed in the main circuit and automatically transmitted to the safeguard circuit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is based upon and claims benefit of priority of Japanese Patent Application No. 2003-58780 filed on Mar. 5, 2003, the content of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a passenger protecting system for an automotive vehicle, the system including passenger protecting devices, such as airbags or seatbelt pretensioners, which are actuated upon detection of a collision. 
   2. Description of Related Art 
   A passenger protecting system having seat sensors for detecting passengers sitting thereon is disclosed in JPA-2002-200963. In this system, whether or not a passenger occupies a seat is detected by a seat sensor. A passenger protecting device for the particular seat which is not occupied is not actuated even when a collision is detected. Passenger protecting devices for other seats which are occupied are actuated upon detection of a collision. The passenger protecting system disclosed therein includes a main control unit, a safeguard control unit and a driving IC (a driving integrated circuit. 
   The main control unit determines switching elements for the protecting devices corresponding to the unoccupied seats based on signals from the seat sensors. Information regarding such switching elements not to be actuated upon detection of a collision is sent to the driving IC and to the safeguard control unit as well. The safeguard control unit also determines, independently from the main control unit, the switching elements not to be actuated upon detection of a collision. Only the switching elements indicated by both of the main and safeguard control units as those not to be actuated are finally selected as the switching elements not to be actuated. In this manner, the passenger protecting system disclosed in JP-A-2002-200963 is able to select the switching elements not to be actuated upon detection of a collision without using a hardware (such as MOSFET switches) disposed outside the passenger protecting system. 
   In the conventional passenger protecting system described above, however, the following problem is involved. That is, the passenger protecting devices corresponding to seats other than the unoccupied seats are all actuated regardless of types of collisions (a front collision, a right side collision or a left side collision). To eliminate this problem, a passenger protecting system in which the switching elements are selected according to types of collision has been proposed. This system will be briefly explained below with reference to  FIG. 4 . 
   The passenger protecting system  100  disclosed in  FIG. 4  is mainly composed of a main control unit  101 , a safeguard control unit  102  and a driving IC  103 . The main control unit  101  includes a main detecting circuit  104  and a main driving signal generating circuit  105 . Similarly, the safeguard control unit  102  includes a safeguard detecting circuit  106  and a safeguard driving signal generating circuit  107 . The driving IC  103  includes an input interface  108  for main driving signals, another input interface  109  for safeguard driving signals, six main switching elements  110  and six safeguard switching elements  111 . Each main switching element  110  is connected in series to each safeguard switching element  111  through a wire L 100 . 
   Operation of the passenger protecting system  100  will be briefly explained, taking a front collision as an example. Acceleration signals at a front collision are fed to the main detecting circuit  104  from main acceleration sensors (not shown in  FIG. 4 ). The main detecting circuit  104  detects a type of collision based on the acceleration signals (a front collision is detected in this example). A signal  113  indicating a front collision is fed to an AND-gate  114 . In the main driving signal generating circuit  105 , a group of register channels  115  for a front collision are pre-programmed. In this particular example, register channels CH 1 , CH 2 , CH 3  and CH 4  are pre-programmed as the register channels for the front collision. Similarly, a register channel CH 5  and a register channel CH 6  are pre-programmed as register channels for a right side collision and for a left side collision, respectively. 
   Both the signal  113  indicating a front collision and the register channels  115  are fed to the AND-gate  114 . The AND-gate  114  outputs main driving signals to register channels CH 1 –CH 4  in the main input interface  108 . Four main switching elements  110  corresponding to the register channels CH 1 –CH 4 , respectively, are driven. 
   The safeguard switching elements  111  are driven by the safeguard control unit  102  in the similar manner as described above. Signals from safeguard acceleration sensors (not shown in  FIG. 4 ) are fed to the safeguard detection circuit  106 . A signal  116  indicating a front collision and pre-programmed register channels  118  (i.e., CH 1 –CH 4 ) are fed to an AND-gate  117 . The AND-gate  117  outputs safeguard driving signals to register channels CH 1 –CH 4  of the safeguard input interface  109 . Four safeguard switching elements  111  corresponding to the register channels CH 1 –CH 4 , respectively, are driven by the safeguard driving signals. 
   When both of the main switching elements  110  and the safeguard switching elements  111  are driven, current flows through the wires L 100  corresponding to CH 1 –CH 4 . Thus, actuators for the passenger protecting devices, such as airbags or seatbelt pretensioners, corresponding to the register channels CH 1 –CH 4  are actuated. 
   The register channels CH 1 –CH 6  can be allocated to respective passenger protecting devices in various ways. Three variations are shown in  FIG. 5 . In variation  1 , for example, a register channel CH 1  is allocated to an airbag positioned in front of a driver, CH 2  to an airbag positioned in front of an assistant, CH 3  to a seatbelt pretensioner for a driver, CH 4  to a seatbelt pretensioner for an assistant, CH 5  to a side airbag for a driver, and CH 6  to a side airbag for an assistant. The allocation of register channels is pre-programmed both in the main driving signal generating circuit  105  and in the safeguard driving signal generating circuit  107 . 
   The allocation of the register channels is not always the same, but it varies according to types of vehicles. Therefore, the allocation of the register channels has to be programmed for each vehicle type. Therefore, it has been difficult to use the main control unit  101  and the safeguard control unit  102  commonly to all types of vehicles. Also, it is required to tune-up program details in the main control unit  101 , such as algorithm for detecting types of collision or detection criteria, according to specifications (such as a body shape, a body rigidity or a distance from an airbag to a driver) of each vehicle type. On the other hand, the safeguard unit  102  can be commonly used to various vehicle types except for the allocation of the register channels mentioned above. Therefore, if the programming of the register channel allocation in the safeguard driving signal generating circuit  107  is eliminated, the safeguard control unit  102  will be commonly used to most types of vehicles. 
   SUMMARY OF THE INVENTION 
   The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an improved passenger protecting system having the safeguard control unit that can be commonly used to various vehicle types. 
   The passenger protecting system according to the present invention is composed of a plurality of passenger protecting devices, such as airbags or seatbelt pretensioners, and a controller for actuating the passenger protecting devices upon detection of a collision. The controller includes a main control unit, a safeguard control unit and a driving integrated circuit (a driving IC). Both control units are connected to the driving IC. 
   The main control unit is composed of a main detecting circuit for detecting types of collision (a front collision, a right side collision and a left side collision) according to signals from main acceleration sensors. Similarly, the safeguard control unit is composed of a safeguard detecting circuit for detecting the types of collision according to signals from safeguard acceleration sensors. When a type of collision is detected by the main detecting circuit, some protecting devices to be actuated at that detected collision are selected from among the plurality of the protecting devices. Signals for driving the selected protecting devices are sent to the driving IC. Similarly, the type of collision is also detected by the safeguard detecting circuit, and protecting devices to be actuated are selected. Signals for driving the selected protecting devices are also sent to the driving IC. When the switching elements in the driving IC corresponding to the selected protecting devices are driven by the driving signals sent from both of the main control unit and the safeguard control unit, the selected protecting devices are actuated. 
   Information regarding the protecting devices to be selected according to the types of collision is pre-programmed in the main control unit, and the information stored in the main control unit is automatically transmitted to the safeguard control unit. The safeguard control unit includes a register frame that is capable of accommodating therein the register channels, the number of which is larger than the number of the plurality of protecting devices. 
   Since the information pre-programmed in the main control unit is automatically transmitted to the safeguard control unit, it is not necessary to pre-program that information in the safeguard control unit independently from the main control unit. Therefore, the safeguard control unit can be used commonly to various types of vehicles. Since the register frame in the safeguard control unit is designed to contain a number of register channels for covering all of the protecting devices, the safeguard control unit can be used commonly to most types of vehicles. Preferably, either of the safeguard detecting circuit or the safeguard driving signal generating circuit, or both, is integrally disposed with the driving IC to further simplify the structure of the controller. 
   Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiment described below with reference to the following drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing an entire structure of a passenger protecting system according to the present invention; 
       FIG. 2  is a block diagram showing a main control unit, a safeguard control unit and a driving integrated circuit used in the passenger protecting system shown in  FIG. 1 ; 
       FIG. 3  is a block diagram showing a main portion of a modified form of the passenger protecting system; 
       FIG. 4  is a block diagram showing a main portion of a conventional passenger protecting system; and 
       FIG. 5  is a table showing examples of various allocation of register channels to passenger protecting devices. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A preferred embodiment of the present invention will be described with reference to accompanying drawings. Referring to  FIGS. 1 and 2 , a structure of a passenger protecting system according to the present invention will be described. As shown in  FIG. 1 , the passenger protecting system  1  is mainly composed of a main control unit  2 , a safeguard control unit  3  and a driving integrated circuit  4  (a driving IC  4 ). A main acceleration sensor  50  for detecting a front collision, a main acceleration sensor  51  for detecting a right side collision and a main acceleration sensor  52  for detecting a left side collision are connected to the main control unit  2 . Similarly, safeguard acceleration sensors  60 ,  61 , and  62  for detecting a front collision, a right side collision and a left side collision, respectively, are connected to the safeguard control unit  3 . 
   The driving IC  4  driven by the output signals from the main control unit  2  and the safeguard control unit  3  is connected to both control units  2 ,  3 . A passenger protecting device  70 , such as an airbag or a seatbelt pretensioner, is actuated by respective actuators  71  (e.g., a squib in case of an airbag) connected to respective channels in the driving IC  4 . 
   The structure of the main control unit  2 , the safeguard control unit  3  and the driving IC  4  will be described in detail with reference to  FIG. 2 . The main control unit  2  includes a main detecting circuit  20  for detecting (or determining) types of collision and a main driving signal generating circuit  21 . The main detecting circuit  20  is connected to the main acceleration sensors  50 ,  51 ,  52  (shown in  FIG. 1 ). Based on the signals fed from the main acceleration sensors  50 ,  51 ,  52 , the main detecting circuit  20  detects types of collision, i.e., it determines which type of collision occurred (a front collision, a left side collision or a right side collision). 
   Information regarding register channels selected for respective types of collision is pre-programmed in the main driving signal generating circuit  21 . In this particular embodiment, register channels CH 1 –CH 4  are selected for the front collision, CH 5  for the right side collision, and CH 6  for the left side collision. When a front collision is detected, a signal  200  indicating the front collision and information  213  as to the register channels CH 1 –CH 4  selected for the front collision are fed to an AND-gate  210  through signal wires S 1 , S 4 , respectively. Similarly, a signal  201  indicating a right side collision and information as to register channels CH 5  selected for the right side collision are fed to an AND-gate  211  through signal wires S 2 , S 5 , respectively. A signal  202  indicating a left side collision and information as to register channels selected for the left side collision are fed to an AND-gate  212  through signal wires S 3 , S 6 , respectively. 
   The safeguard control unit  3  includes a safeguard detecting circuit  30  for detecting (or determining) types of collision and a safeguard driving signal generating circuit  31 . The safeguard detecting circuit  30  is connected to the safeguard acceleration sensors  60 ,  61 ,  62  (shown in  FIG. 1 ). Based on the signals fed from the safeguard acceleration sensors  60 ,  61 ,  62 , the safeguard detecting circuit  30  detects types of collision, i.e., it determines which type of collision occurred (a front collision, a left side collision or a right side collision). 
   A register frame  313  for the front collision, a register frame  314  for the right side collision and a register frame  315  for the left side collision, each frame being able to accommodate six register channels therein, are provided in the safeguard driving signal generating circuit  31 . The information  213  as to register channels CH 1 –CH 4  selected for the front collision and stored in the main driving signal generating circuit  21  is transmitted to the register frame  313  through a signal wire S 13 . Similarly, the information  214  and the information  215  stored in the main driving signal generating circuit  21  are transmitted to the register frames  314 ,  315 , respectively, through the signal wire S 13 . 
   When the front collision is detected, a signal  300  indicating the front collision and the information  213  transmitted to the register frame  313  are fed to an AND-gate  310  through signal wires S 7 , S 10 , respectively. Similarly, a signal  301  indicating the right side collision and the information  214  transmitted to the register frame  314  are fed to an AND-gate  311  through signal wires S 8 , S 11 , respectively. A signal  302  indicating the left side collision and the information  215  transmitted to the register frame  315  are fed to an AND-gate  312  through signal wires S 9 , S 12 , respectively. 
   The driving IC  4  includes a main input interface  40 , a safeguard input interface  41 , six main switching elements  42  and six safeguard switching elements  43 . The main input interface  40  having six register channels CH 1 –CH 6  is connected to the AND-gates  210 ,  211 ,  212  through a signal wire S 14 . Similarly, the safeguard input interface  41  having six register channels CH 1 –CH 6  is connected to the AND-gates  310 ,  311 ,  312  through a signal wire S 15 . 
   In this particular embodiment, the register channels CH 1 –CH 6  are allocated to the respective passenger protecting devices as shown in variation  1  of  FIG. 5 . Each one of the safeguard switching elements  43  is connected in series to each one of the main switching elements  42  through a wire L 1 . For example, the register channel CH 1  is allocated to the airbag positioned in front of the driver (refer to variation  1  in  FIG. 5 ). A squib  71  for actuating the airbag is connected in the wire L 1 . 
   Now, operation of the passenger protecting system  1  will be described, taking the front collision as an example. When the signal from the acceleration sensor  50  for the front collision is fed to the main detecting circuit  20 , the main detecting circuit generates the signal  200  indicating the front collision. Both the signal  200  and the information  213  as to the register channels CH 1 –CH 4  pre-programmed for the front collision are fed to the AND-gate  210 . The AND-gate  210  outputs a main driving signal which is fed to the main input interface  40 . The main switching elements  42  corresponding to the four register channels CH 1 –CH 4  are driven by the main driving signal. 
   Similarly, when the signal from the safeguard acceleration sensor  60  for the front collision is fed to the safeguard detecting circuit  30 , the safeguard detecting circuit  30  generates the signal  300  indicating the front collision. Both the signal  300  and the information  213  transmitted from the main driving signal generating circuit  21  to the register frame  313  are fed to the AND-gate  310 . The AND-gate  310  outputs a safeguard driving signal which is fed to the safeguard input interface  41 . The safeguard switching elements  43  corresponding to the four register channels CH 1 –CH 4  are driven by the safeguard driving signal. 
   When both of the main switching elements  42  and the safeguard switching element  43  are driven, current flows through the wires L 1  corresponding to CH 1 –CH 4 . Thus, the passenger protecting devices corresponding to CH 1 –CH 4  are actuated. 
   Following advantages are attained by the present invention. Since the information  213 ,  214 ,  215  as to the register channels selected for respective types of collision, which is pre-programmed in the main driving signal generating circuit  21 , is automatically transmitted to the respective register frames  313 ,  314 ,  315 , it is not necessary to program such information in the safeguard control unit  3 . In other words, the process for programming such information in the safeguard control unit  3  is eliminated. 
   Since the register frames  313 ,  314 ,  315  are designed to accommodate six register channels, the safeguard control unit  3  can be commonly used for various types of vehicles as long as the number of passenger protecting devices is equal to or less than six. Since the safeguard control unit  3  is commonly used to various types of vehicles, it can be manufactured at low costs. Further, the cost for entire passenger protecting system  1  can be reduced. 
   The passenger protecting system  1  shown in  FIG. 2  may be modified to a form shown in  FIG. 3 . In this modified form, the safeguard driving signal generating circuit  31  is integrally formed with the driving IC  4 . Other structures and operation of the modified form are the same as those of the embodiment described above. Since the driving IC  4  can be commonly used to various vehicle types, the structure of the passenger protecting system  1  is further simplified by combining the safeguard driving signal generating circuit  31  with the driving IC  4 . In addition, the signal wire S 15  can be embedded in the driving IC  4 , noise influence on the signal wire S 15  is reduced or eliminated. Alternatively, the safeguard detecting circuit  30  may be integrally formed with the driving IC  4 , or both of the safeguard detecting circuit  30  and the safeguard driving signal generating circuit  31  may be integrally formed with the driving IC  4 . 
   The present invention is not limited to the embodiment described above, but it may be variously modified. For example, though the register frames  313 ,  314 ,  315  are designed to accommodate six register channels in the foregoing embodiment, they may be designed to accommodate more than six register channels. Further, it is not necessary that each register frame accommodates the same number of the register channels. The number of the register channels can be variously selected according to requirement of actual applications. The information as to the register channels pre-programmed in the main driving signal generating circuit  21  may be stored therein in a form of logical values, 1 and 0. Such information transmitted from the main driving signal generating circuit  21  to the safeguard driving signal generating circuit  31  may be stored therein in a form of logical values. Though the collision types are defined in three types, i.e., the front collision, the right side collision and the left side collision in the foregoing embodiment, other types of collision, e.g., a rollover collision or a backward collision, may be defined. 
   While the present invention has been shown and described with reference to the foregoing preferred embodiment, it will be apparent to those skilled in the art that changes in form and detail may be made therein without departing from the scope of the invention as defined in the appended claims.