Abstract: This invention relates to an acceleration sensor device suitable for self-checking while a vehicle is being driven and a self-checking circuit therefor. An acceleration sensor device for self-checking while driving is comprised of a planar vibrator having a piezoelectric area and a non-piezoelectric area and a plurality of first electrodes provided on an upper face of the piezoelectric area of the planar vibrator. At least one second electrode is provided on an upper face of the non-piezoelectric area of the planar vibrator, and a third electrode is provided on the lower face of the planar vibrator. Inputs to the self-checking circuits provide an output that represents the operating state of the acceleration sensor.

Abstract: This invention relates to an acceleration sensor system having a self-checking operation of an air bag safety system while a vehicle is being driven. An acceleration sensor element suitable for self-checking while a vehicle is driven is obtained by a planar piezoelectric element supported so that it can vibrate, a detecting electrode provided on an upper face of the planar piezoelectric element, and an actuator to add vibrations at a predetermined frequency to the planar piezoelectric element. A sensitivity checking circuit generates a sensitivity checking signal representing sensitivity of an acceleration sensed from a detected signal. A signal processing circuit generates an acceleration signal representing the applied acceleration to the acceleration sensor from the detected signal.