Piezoelectric accelerometer for detecting vibration in vehicle

摘要

The piezoelectric element (4) held between upper and lower electrodes (3a,3b) on an insulating plate is electrically stressed by an overlying mass under vertical acceleration. The electrodes are wired to a charge amplifier (6) incorporating an operational amplifier (20) on the same plate, with a temp.-compensating capacitor (C1) in parallel with them. The charge amplifier circuit includes a resistance (R3) in parallel with the capacitor, and the lower electrode (3b) is returned to the reference potential of a fixed resistive divider (R1,R2). The output is amplified (7), filtered (8b) and taken through a feedthrough capacitor (10b) to a signal line (33).