JP2012061891A - Seat belt device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat belt device that detects a connecting failure of a rotation sensor or the like, even when a motor is stopped.SOLUTION: The seat belt device 1 rotates a belt spool 300 of a seat belt retractor 21 using the motor 200 to wind up a seat belt 11. The seat belt device 1 includes: a sensor 308 which detects a rotation of the belt spool 300 by supply of a sensor power, to output a sensor signal; a sensor input circuit to which the sensor signal of the sensor 308 is input; a measuring unit 416 which measures an output value of an output signal output from the sensor input circuit; and a failure diagnosis unit 406 which carries out failure diagnosis on the basis of the output value measured by the measuring unit 416 while the supply of the sensor power to the sensor 308 is stopped.

Description

  The present invention relates to a vehicle seat belt device, for example, a vehicle seat belt device that winds up a seat belt by rotating a belt spool of a seat belt retractor with a motor.

  A conventional vehicle seat belt device diagnoses a failure of a rotation sensor or a sensor input circuit by converting an input signal of a rotation sensor that transmits a rotation signal of a belt spool into a digital signal by an ECU and performing software processing. (See Patent Document 1).

JP 2007-326538 A

  However, in the conventional apparatus, unless the spool rotates, an input signal does not enter the ECU from the rotation sensor, so that a connection failure with the rotation sensor cannot be detected before the motor is driven. Therefore, for example, there is a problem that failure detection cannot be performed when the motor is not energized for initial diagnosis or the like.

  The present invention has been made in view of the above points, and an object thereof is to provide a seat belt device capable of diagnosing a connection failure with a rotation sensor even when the motor is stopped. It is.

  The seat belt device of the present invention that solves the above problem is a seat belt device that winds up the seat belt by rotating the belt spool of the seat belt retractor with a motor, and the belt spool of the seat belt retractor is supplied by a sensor power supply. A sensor unit that detects rotation and outputs a sensor signal, a sensor input circuit unit to which a sensor signal of the sensor unit is input, a measurement unit that measures an output value of an output signal output from the sensor input circuit unit, and a sensor And a failure diagnosis unit that performs failure diagnosis based on an output value measured by the measurement unit in a state where supply of sensor power to the unit is stopped.

  According to the seat belt device of the present invention, the failure diagnosis unit performs failure diagnosis based on the signal value of the signal path measured by the measurement unit while the supply of sensor power is stopped. For example, the supply of sensor power is stopped. However, if a predetermined signal value is detected by the measurement unit, it can be determined that a VB short circuit has occurred in the signal path of the sensor unit.

  Therefore, a failure diagnosis can be performed without rotating the belt spool, the control of the seat belt device can be performed with high reliability, and the safety for passengers can be greatly improved.

  According to the seat belt device of the present invention, the sensor unit includes the first sensor unit and the second sensor unit, and the measurement unit inputs the sensor signal value of the first sensor unit. A first measurement means for measuring the signal value of the second signal means, and a second measurement means for measuring the signal value of the second signal path through which the sensor signal value of the second sensor means is input, and a failure diagnosis unit Have a test signal output means for outputting a test signal to the first signal path.

  Then, the test signal is output to the first signal path in a state where the supply of the sensor power to the sensor unit is stopped, and the first signal value measured by the first measuring unit and the second measuring unit are used for measurement. Based on the second signal value, the presence / absence of a short-circuit between the signal lines between the first signal path and the second signal path is diagnosed. The signal value of the test signal can be measured from the line, and the signal value of the test signal can be measured from only one of the signal lines when no short-circuit between the signal lines has occurred. Therefore, it is possible to determine whether or not a short circuit between the signal lines has occurred.

1 is a layout diagram of a vehicle safety device to which a seat belt device according to a first embodiment is applied. The figure explaining the structure of a seatbelt apparatus. The figure explaining the structure of a retractor. The control circuit diagram of a seatbelt apparatus. The figure which shows the change of the waveform at the time of VB short-circuit occurrence. The figure which shows the change of the detection waveform at the time of short circuit between signal lines. The flowchart explaining a failure diagnosis control process. FIG. 6 is a control circuit diagram of the seat belt device according to the second embodiment. The figure which shows the change of the detection waveform at the time of VB short and GND short. The figure which shows an example of the change of the detection waveform at the time of short circuit between signal lines. The figure which shows another example of the change of the detection waveform at the time of short circuit between signal lines.

  Next, examples of the present invention will be described below.

[Example 1]
FIG. 1 is a layout diagram of a vehicle safety device to which a seat belt device of the present invention is applied, and FIG. 2 is a diagram illustrating the configuration of the seat belt device of this embodiment.

  As shown in FIG. 1, the vehicle 112 has an obstacle sensor 102 that outputs a signal corresponding to the distance from the obstacle attached to the front portion of the vehicle. The output signal of the obstacle sensor 102 is transmitted to the collision determination controller 106 that is electrically connected to the obstacle sensor 102. A signal from the wheel speed sensor 104 that outputs a signal corresponding to the vehicle speed is also transmitted to the collision determination controller 106 that is electrically connected to the wheel speed sensor 104.

  The collision determination controller 106 determines whether or not the vehicle 112 collides with an obstacle based on signals from the obstacle sensor 102 and the wheel speed sensor 104. For example, when the distance to the obstacle obtained from the output signal of the obstacle sensor 102 is shorter than a predetermined value and the vehicle speed obtained from the output signal of the wheel speed sensor 104 is higher than the predetermined value, The collision determination controller 106 determines that the vehicle 112 collides with an obstacle as it is, and outputs a command signal to the brake assist device 108 and the retractor 21 of the seat belt device 1 before the vehicle 112 collides with the obstacle.

  The brake assist device 108 and the seat belt drive controller 110 are electrically connected to the collision determination controller 106, and each execute a predetermined operation based on a command signal from the collision determination controller 106.

  As shown in FIG. 2, the seat belt device 1 includes a seat belt (webbing) 11 that restrains the body of the occupant 2 to the seat 3. The seat belt 11 has a so-called three-point seat having an upper belt portion 11a that restrains the upper body of the occupant 2 by stroking and a waist belt portion 11b that restrains the waist of the occupant 2 across the left and right in front of the abdomen. It is a belt.

  One end of the waist belt portion 11 b is fixed to the vehicle body portion at the lower part of the passenger compartment by an anchor plate 12. One end of the upper body belt portion 11a is inserted through a through anchor 13 provided in the vicinity of the shoulder of the occupant 2 and folded downward, and is connected to the belt reel of the retractor 21 and can be wound up. The other end of the waist belt portion 11b and the other end of the upper belt portion 11a constitute a common end portion, and a tongue plate 15 is attached thereto. The tongue plate 15 has a structure that can be attached to and detached from a buckle 16 provided at the lower part of the passenger compartment in the vehicle width direction center side than the seat 3.

  The retractor 21 of the seat belt apparatus 1 is provided with a motor 22, and the belt 11 can be wound by rotating the motor 22. The motor 22 includes a DC motor or a brushless motor, and is controlled by a motor control unit of a seat belt retractor control device (hereinafter, ECU) 402.

  The motor control unit of the ECU 402 controls the motor 22 to perform a pre-crash operation for the purpose of safety of the occupant 2, automatic fitting for the purpose of improving comfort or automatic storage of the belt 11, and warning operation for calling attention to the occupant 2 Take up.

  For example, let us consider a case where the occupant 2 is driving the vehicle 112 and the occupant 2 moves to the front of the vehicle although it is minute, and a gap is generated between the occupant 2 and the seat 3. In such a situation, when the vehicle 112 collides with an obstacle, the occupant 2 is not restrained by the seat 3, and as such, may be struck against the seat 3 and receive a shock on the body.

  The seat belt device 1 can wind up the seat belt 11 before the vehicle 112 and the obstacle collide with the motor 22 included in the retractor 21, and eliminate the gap between the occupant 2 and the seat 3. Therefore, when the vehicle 112 and the obstacle collide, the occupant 2 can be already restrained to the seat 3, and the impact received by the occupant 2 from the seat 3 can be reduced.

  3A and 3B are diagrams illustrating the configuration of the retractor. FIG. 3A is a diagram illustrating the overall configuration, and FIG. 3B is a configuration diagram of the rotation detection unit.

  The retractor 21 includes a belt spool 300 for winding up the seat belt 11 (see FIGS. 1 and 2) and a motor 200 that rotationally drives the belt spool 300. The belt spool 300 is rotatably supported by a retractor body (not shown) by a spool shaft 302. The spool shaft 302 is connected to the motor drive shaft 200a of the motor 200 via a gear mechanism 304 that transmits power. The spool shaft 302 is provided with a rotation detection unit including a magnetic disk 306 and a Hall IC 308.

  The magnetic disk 306 is connected to the spool shaft 302 at the center, and rotates in synchronization with the rotation of the spool shaft 302. A magnetic pole portion 310 in which N-pole regions 310 a and S-pole regions 310 b are alternately arranged is provided on the peripheral edge of the magnetic disk 306.

  The Hall IC 308 constitutes a rotation sensor that detects the rotation of the magnetic disk 306, and is arranged such that the Hall IC 308 a and the Hall IC 308 b face the magnetic pole portion 310 and are aligned along the rotation direction of the magnetic disk 306. .

  The Hall IC 308a and the Hall IC 308b react to the N-pole region 310a and the S-pole region 310b of the magnetic pole portion 310, respectively, and each output a pulse signal having a phase shift as a sensor signal. By calculating the pulse signal, it is possible to detect the rotation speed of the spool 300 and the winding amount of the belt 11. The Hall ICs 308a and 308b may use, for example, a non-contact type MR (magnetoresistive element) or a contact type variable resistance.

  FIG. 4 is a control circuit diagram of the seat belt device.

  The seat belt device 1 has a seat belt retractor control device (hereinafter referred to as ECU) 402, to which a Hall IC 308 (308a, 308b) and a power source VB 400 are connected.

  The ECU 402 includes a VCC regulator 404, a VSN regulator 408, a CPU 406, and a sensor input circuit unit.

  When power supply VB 400 supplied from a vehicle battery (not shown) and an alternator driven by the engine is supplied to ECU 402, the vehicle battery voltage is supplied to VCC regulator 404 inside ECU 402.

  The VCC regulator 404 generates a control power supply VCC (5 V) from the power supply VB 400 and supplies it to a signal system element such as a CPU (Central Processing Unit) 406 that performs signal processing. In addition, the VCC regulator 404 has a function of periodically receiving a signal from the CPU 406, monitoring the operation of the CPU 406, a function of resetting the CPU 406, and the like.

  The power supply VB 400 also supplies power to the VSN regulator 408. The VSN regulator 408 generates a sensor power supply VSN supplied to the Hall IC 308 (sensor unit). The CPU 406 controls on / off of the VSN regulator 408, that is, supply or stop of the sensor power supply VSN.

  The sensor power supply VSN output from the VSN regulator 408 is supplied to the Hall IC 308. Further, the GND of the Hall IC 308 is connected to the sensor GND of the ECU 402. Of the Hall ICs 308a and 308b, the sensor signal A from the Hall IC 308a (first sensor means) is input to the sensor input circuit section (first sensor input circuit means) in the ECU 402 via the signal line 410a.

  The sensor signal B from the Hall IC 308b (second sensor means) is input to the sensor input circuit section (second sensor input circuit means) in the ECU 402 via the signal line 410b. Here, the GND of the Hall IC 308 may also serve as the sensor signal A or the sensor signal B. At this time, the signal value of the sensor signal A of the Hall IC 308a is defined as a sensor signal value Vina, and the signal value of the sensor signal B of the Hall IC 308b is defined as a sensor signal value Vinb.

  The sensor signal value Vina of the Hall IC 308a is input to the signal line 410a of the EUC 402, and an RC low-pass for noise removal configured by a resistor (low-pass filter resistor) 412a and a capacitor (low-pass filter capacitor) 414a of the sensor input circuit unit. The signal is input to the A / D converter 416a and the comparator 418a through the filter. A pull-down resistor 420a is connected to the signal line 410a. The signal line 410a between the Hall IC 308a and the ECU 402 and the signal line 410a of the ECU 402 constitute a signal path (first signal path) of the signal A of the Hall IC 308a.

  The comparator 418a compares the sensor signal A with a preset threshold Th1, determines HI, LO, and transmits the result to the CPU 406. On the other hand, the A / D converter 416a constitutes a measuring unit that measures the output value of the output signal output from the sensor input circuit unit, measures the signal value of the sensor signal A, converts it to a digital value, The value is transmitted to the failure diagnosis unit of the CPU 406 (first measurement means). The output value of the A / D converter 416a is defined as an A / D converter output value Vouta (first output value).

  Similarly, the sensor signal value Vinb of the Hall ICB 308b is input to the signal line 410b of the sensor input circuit unit, and is connected to the A / D converter 416b via the RC low pass filter for noise removal constituted by the resistor 412b and the capacitor 414b. Input to the comparator 418b. A pull-down resistor 420b is connected to the signal line 410b. The signal path 410b between the Hall IC 308b and the ECU 402 and the signal line 410b of the sensor input circuit constitute a signal path (second signal path) of the signal B of the Hall IC 308b.

  The comparator 418b compares the sensor signal B with a preset threshold Th2, determines HI, LO, and transmits the result to the CPU 406. On the other hand, the A / D converter 416b constitutes a measurement unit that measures the output value of the output signal output from the sensor input circuit unit, converts the signal value of the sensor signal B into a digital value, and converts the value into a digital value. This is transmitted to the failure diagnosis unit of the CPU 406 (second measuring means). The output value of the A / D converter 416b is set as an A / D converter output value Voutb (second output value).

  The CPU 406 includes a test signal output unit 422 that can output a test signal to the sensor input circuit unit. More specifically, the CPU 406 outputs a test signal between the resistor 412a of the signal line 410a and the A / D converter 416a. It has a configuration that can output.

  The test signal output unit 422 is set to input setting or high impedance setting when failure diagnosis is not performed. The test signal output unit 422 only needs to have a configuration for outputting to either the sensor signal A side or the sensor signal B side. For example, the resistor 412b of the signal line 410b of the sensor input circuit unit and the A / D converter A test signal may be output between 416b and 416b. The value of the test signal output unit 422 is set as the test signal output value Vc.

  Further, the CPU 406 includes a failure diagnosis unit that performs failure diagnosis based on the A / D converter output values Vouta and Voutb. The failure diagnosis unit is implemented by executing predetermined arithmetic processing by the CPU 406.

  Next, the control contents of the failure diagnosis unit will be described with reference to FIGS.

  FIG. 5 is a diagram illustrating a change in the detection signal when a VB short-circuit occurs.

  The sensor signal values Vina and Vinb when the VSN regulator 408 is off and the motor is stopped are pulled down to GND by pull-down resistors 420a and 420b. Therefore, in the case of normal (no failure), the output values Vouta and Voutb of the A / D converters 416a and 416b output values less than the GND short detection threshold value (Vref1).

  When a VB short circuit occurs in the signal path of the sensor signal A due to, for example, a short circuit between the power supply VB and the signal line 410a (t11), the sensor signal value Vina changes from LO to HI. The A / D converter output value Vouta also changes from LO to HI, and becomes higher than the VB short detection threshold (Vref2). Therefore, the CPU 406 can determine that a VB short has occurred in the signal path of the signal A, and can diagnose that there is a connection failure with the Hall IC 308.

  FIG. 6 is a diagram illustrating changes in the detection signal when a short-circuit between signal paths occurs.

  When the test signal output unit 422 outputs the HI test signal Vc while the VSN regulator 408 is in the OFF state, in the normal case, the A / D converter output value Vouta as shown between the timings t21 and t22 in FIG. , Voutb, only the A / D converter output value Vouta changes from LO to HI and becomes higher than the VB short detection threshold (Vref2).

  However, in a state where a short between the signal paths occurs between the signal path of the sensor signal A and the signal path of the sensor signal B, such as a short circuit between the sensor signal lines 410a and 410b (t23), the test signal When the HI test signal Vc is output by the output unit 422 (t24), both of the A / D converter output values Vouta and Voutb change from LO to HI, and each becomes higher than the VB short detection threshold (Vref2). Therefore, the CPU 406 can determine that a short-circuit between signal paths has occurred, and can diagnose that there is a connection failure with the Hall IC 308.

  FIG. 7 is a flowchart for explaining the processing contents of the failure diagnosis control.

  First, when the vehicle battery voltage is supplied to the VCC regulator 404 inside the ECU 402 (600), for example, when the vehicle ignition switch transitions from OFF to ON, the CPU 406 is reset (602), and then the Hall ICs 308a and 308b Connection initial diagnosis is started (604).

  First, diagnose VB short. Here, the A / D converter output value Vouta of the Hall IC 308a and the A / D converter output value Voutb of the Hall IC 308b are acquired, and both of the A / D converter output values Vouta and Voutb are equal to or less than the GND short detection threshold (Vref1). Confirmation is made (606). If at least one of the output values is equal to or greater than the GND short detection threshold (Vref1), it is determined that there is a connection failure with the Hall IC 308 (608), and the diagnosis is terminated (616).

  On the other hand, if both the A / D converter output values Vouta and Voutb are within the normal range below the GND short detection threshold value (Vref1), then a signal path short diagnosis is performed. Here, the test signal Vc (= 5V) is output from the test signal output unit 422 of the CPU 406 (610), the A / D converter output value Vouta of the Hall IC 308a, the A / D converter output value Voutb of the Hall IC 308b, and the VB short circuit. Comparison with the detection threshold (Vref2) is performed (612).

  If both the A / D converter output value Vouta of the Hall IC 308a and the A / D converter output value Voutb of the Hall IC 308b are equal to or greater than the VB short detection threshold (Vref2), it is assumed that a short circuit between signal paths has occurred and the Hall IC 308 The connection failure is confirmed (608), and the diagnosis is finished (616).

  On the other hand, when the A / D converter output value Vouta of the Hall IC 308a is equal to or higher than the VB short detection threshold (Vref2) and the A / D converter output value Voutb of the Hall ICB (308b) is equal to or lower than the GND short detection threshold (Vref1). Determines that the signal path short-circuit has not occurred and the connection with the Hall IC 308 is normal (614), and ends the Hall IC connection diagnosis while the motor is stopped (616).

  With this diagnosis, when the VSN regulator 408 is off, one of the A / D converter output value Vouta of the Hall IC 308a and the A / D converter output value Voutb of the Hall IC 308b is always at the HI potential, so the presence or absence of a failure is detected. It becomes possible.

  When the failure diagnosis unit diagnoses that there is a connection failure with the Hall IC 308, the ECU 402 prohibits control of the motor 22 by the motor control unit.

  According to the seat belt device 1 of the present embodiment, a connection failure of the Hall IC 308 can be detected even when the motor is stopped. Therefore, without having to actually pull out or retract the seat belt, it is possible to grasp the presence or absence of a failure in advance and to perform highly reliable control. As a result, safety for passengers in the vehicle is improved. Can be made. Further, by configuring the A / D input function and the sensor signal input function in the same terminal of the CPU 406, it is possible to configure with a minimum number of components, which can contribute to the miniaturization of the ECU 402.

[Example 2]
Next, Example 2 will be described below.

  FIG. 8 is a control circuit diagram of the seat belt device according to the second embodiment.

  What is characteristic in this embodiment is that a pull-up resistor 424a to the control power supply VCC is added to the sensor input circuit of the ECU 402. In the ECU 402, a pull-down resistor 420a to GND and a pull-up resistor 424a to a control power supply VCC are connected to a signal line 410a of a sensor input circuit section (first sensor input circuit means) for sensor signal A. Similarly, a sensor signal A pull-down resistor 420b to GND and a pull-up resistor 424b to the control power supply VCC are connected to the signal line 410b of the B sensor input circuit section (second sensor input circuit means).

  FIG. 9 is a diagram showing changes in the detected waveform when a VB short circuit and a GND short circuit occur.

  When normal, the sensor signal values Vina and Vinb while the VSN regulator 408 is off and the motor is stopped become the potential (intermediate potential) divided by the pull-up resistors 424a and 424b and the pull-down resistors 420a and 420b.

  Therefore, as shown in FIG. 9, the A / D converter output values Vouta and Voutb of the sensor signals A and B from the Hall ICs 308a and 308b are between the GND short detection threshold (Vref1) and the VB short detection threshold (Vref2). Output the value.

  For example, when a VB short occurs in the signal line 410a of the Hall IC 308a (t31), the sensor signal value Vina changes to HI, and the A / D converter output value Vouta also changes from the intermediate potential to HI to detect VB short. It becomes higher than the threshold (Vref2). Therefore, the CPU 406 can detect that a VB short has occurred in the signal path of the signal A, and can diagnose that there is a connection failure with the Hall IC 308.

  On the other hand, when a GND short occurs in the signal line 410b of the Hall IC 308b (t32), the sensor signal value Vinb changes to LO, the A / D converter output value Voutb also changes from the intermediate potential to LO, and the GND short detection threshold ( Vref1). Therefore, the CPU 406 can detect that a GND short has occurred in the signal path of the signal B, and can diagnose that there is a connection failure with the Hall IC 308.

  FIG. 10 is a diagram illustrating an example of a change in the detection waveform when a signal line short-circuit occurs.

  Since the test signal output unit 422 is set as an input, in the normal case, the sensor signal values Vina and Vinb are intermediate potentials divided by the pull-up resistor 424 and the pull-down resistor 420.

  Therefore, when the test signal output unit 422 outputs an HI test signal while the VSN regulator 408 is off, the signal line connected to the test signal output unit 422 as shown between t41 and t42 in FIG. Only the A / D converter output value Vouta at 410a changes from LO to HI and becomes higher than the VB short detection threshold (Vref2).

  However, if a test signal output unit 422 outputs a HI test signal in a state where a short circuit between the signal lines occurs between the sensor signal lines 410a and 410b (t43), as shown in FIG. 10 after t44. In addition, both of the A / D converter output values Vouta and Voutb change from LO to HI, and each becomes higher than the VB short detection threshold (Vref2). Therefore, the CPU 406 can detect that a short circuit between signal paths has occurred, and can diagnose a connection failure of the Hall IC 308.

  FIG. 11 is a diagram illustrating another example of a change in the detected waveform when a short between signal lines occurs.

  The test signal output unit 422 has a configuration for outputting an LO test signal. In the normal case, the sensor input values Vina and Vinb before outputting the test signal are potentials divided by the pull-up resistor 424 and the pull-down resistor 420 to VCC.

  When the VSN regulator 408 is off and the test signal output unit 422 outputs an LO test signal, the signal line connected to the test signal output unit 422 is shown between t51 and t52 in FIG. Only the A / D converter output value Vouta 410a changes from the intermediate potential to LO, and becomes lower than the GND short detection threshold (Vref1).

  However, when a short circuit between the signal lines occurs between the sensor signal lines 410a and 410b (t53), when the test signal output unit 422 outputs the LO test signal, as shown after t54 in FIG. Both the A / D converter output values Vouta and Voutb change from the intermediate potential to LO, and each becomes lower than the GND short detection threshold (Vref1). Therefore, the CPU 406 can diagnose whether or not a connection failure with the Hall IC 308 has occurred. As described above, according to the seat belt device 1 of the second embodiment, the test signal output by the test signal output unit 422 can be detected by either HI or LO.

  In addition, this invention is not limited to the above-mentioned Example, A various change is possible in the range which does not deviate from the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Seat belt apparatus 2 Crew 3 Seat 11 Seat belt 21 Retractor 22 Motor 102 Obstacle sensor 104 Wheel speed sensor 106 Collision judgment controller 108 Brake assist device 110 Seat belt drive controller 112 Vehicle 200 Motor 200a Motor drive shaft 300 Belt spool 302 Spool Shaft 304 Gear mechanism 306 Magnetic disk 308a, 308b Hall IC (sensor unit)
310 Magnetic pole portion 310a N pole region 310b S pole region 400 Power supply VB
402 ECU
404 VCC regulator 406 CPU
408 VSN regulators 410a and 410b Signal lines 412a and 412b Low-pass filter resistors 414a and 414b Low-pass filter capacitors 416a and 416b A / D converters (measurement units)
418a, 418b Comparator 420a, 420b Pull-down resistor 422 Test signal output unit 424a, 424b Pull-up resistor

Claims (9)

A seat belt device for winding a seat belt by rotating a belt spool of a seat belt retractor with a motor,
A sensor unit for detecting rotation of the belt spool by supplying sensor power and outputting a sensor signal;
A sensor input circuit unit to which a sensor signal of the sensor unit is input;
A measurement unit for measuring an output value of an output signal output from the sensor input circuit unit;
A failure diagnosis unit that performs failure diagnosis based on an output value measured by the measurement unit in a state where supply of the sensor power to the sensor unit is stopped;
A seat belt device comprising:   The failure diagnosis unit compares the output value with a preset threshold value and performs diagnosis of at least one of a power supply short circuit and a GND short circuit of a signal path from the sensor unit to the sensor input circuit unit, The seat belt device according to claim 1. The sensor input circuit unit includes a pull-down resistor that pulls down a signal value of the sensor signal in a state where supply of the sensor power is stopped,
The seat according to claim 2, wherein the failure diagnosis unit determines that a power supply short circuit has occurred in the signal path when the output value is higher than a preset VB short detection threshold value. Belt device. The sensor input circuit unit includes a pull-up resistor that pulls up the signal value of the sensor signal in a state where the supply of the sensor power supply is stopped.
The sheet according to claim 3, wherein the failure diagnosis unit determines that a GND short has occurred in the signal path when the output value is lower than a preset GND short detection threshold. Belt device. The sensor unit includes first sensor means and second sensor means,
The sensor input circuit section includes a first sensor input circuit means to which a sensor signal of the first sensor means is input and a second sensor input circuit means to which a sensor signal of the second sensor means is input. Prepared,
The measurement unit includes a first measurement unit that measures an output value of a first output signal output from the first sensor input circuit unit, and a second output that is output from the second sensor input circuit unit. A second measuring means for measuring the output value of the output signal;
The failure diagnosis unit includes a test signal output unit that outputs a test signal to the first sensor input circuit unit, and outputs the test signal in a state where supply of the sensor power to the sensor unit is stopped. The failure diagnosis is performed based on a first output value measured by the first measuring unit and a second output value measured by the second measuring unit. Seat belt device.   The failure diagnosis unit compares the first measured value and the second measured value with a preset threshold value, and compares the first measured value and the first sensor input circuit means. 6. A short circuit between signal paths between one signal path and a second signal path from the second sensor means to the second sensor input circuit means is diagnosed. Seat belt device. The sensor input circuit unit includes a pull-down resistor that pulls down the first signal value and the second signal value in a state where the supply of the sensor power supply is stopped.
When the failure diagnosis unit outputs a HI test signal to the first sensor input circuit means, the first output value is higher than a preset VB short detection threshold and the second output value Is lower than a preset GND short detection threshold, it is determined that no short circuit between the signal paths has occurred, and the first output value is less than or equal to the VB short detection threshold or the second output value The seatbelt device according to claim 6, wherein when the value is equal to or less than the GND short detection threshold, it is determined that a short circuit between the signal paths has occurred. The sensor input circuit unit includes a pull-down resistor that pulls down the first signal value and the second signal value in a state where supply of the sensor power is stopped, the first signal value, and the second signal. Has a pull-up resistor to pull up the value,
When the failure diagnosis unit outputs an LO test signal to the first sensor input circuit means, the first output value and the second signal value are lower than a preset GND short detection threshold value. In this case, it is determined that a short circuit between the signal lines has occurred. A motor control unit for controlling the motor based on a sensor signal of the sensor unit;
9. The motor control unit according to claim 1, wherein the motor control unit prohibits motor control based on a sensor signal of the sensor unit when the failure diagnosis unit diagnoses that there is a failure. A seat belt device according to claim 1.

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