| 摘要 |
PURPOSE:To automatically diagnose whether or not an acceleration sensor or a signal processing circuit are troubled or not by adding a diagnostic pulse generator and a diagnostic circuit. CONSTITUTION:The diagnostic pulse generator 11 confirms, for example, a vehicle speed signal and generates a diagnostic pulse. Then this pulse is inputted to an input terminal 1b to generate an output voltage by reverse piezoelectric effect at the output terminal 1a of a pressure element 1, and the period and voltage of the diagnostic pulse are so set that an integrator 4 outputs a voltage higher than the set voltage of a 1st comparator 5. Further, when the diagnostic pulse is generated, a transistor (TR) 6 is turned on unless the element 1 and signal processor 2 are troubled, and a voltage is inputted to the diagnostic circuit 12. Furthermore, when the voltage is not inputted to the circuit 12 even a specific time after the diagnostic pulse is generated, it is judged that the element or circuit is troubled to turn off a fail-safe relay 10 and operate an alarm 13. Thus, it is judged automatically whether or not the circuit 2, etc., is troubled. |
