| 摘要 |
<p>PURPOSE:To confirm the function of an acceleration sensor directly at all times by adding an electric alternating current signal at all times to the piezoelectric acceleration sensor thereby to act the mechanical vibration to a vibrator of the sensor. CONSTITUTION:For the purpose of self-checking of characteristics of a sensor, a drive terminal 52 is provided to apply a voltage and vibrate a piezoelectric ceramic element 60. The drive terminal 52 is connected to a driving electrode 60b of the element 60 via a lead frame 80. When an alternating current voltage, e.g. a sine wave or a rectangular wave of 1kHz is applied to the terminal 52, the piezoelectric ceramic of the outer electrode 6Ob of the element 60 functions as an actuator, with contracting and expanding with 1kHz. The piezoelectric ceramic of an inner electrode 60a of the element 60 contracts and expands as well, and moreover, in the similar manner as a vibrating plate 51. Accordingly, the whole of the vibrator warps, whereby a 1kHz sensor output is obtained. Since the vibrator is directly vibrated by the alternating current voltage applied to the terminal 52, it is possible to detect a failure at all times if the frequency is separated from the vibration spectrum at the time of a to-be-detected shock.</p> |
