| 摘要 |
PROBLEM TO BE SOLVED: To provide a capacitive physical quantity detecting device capable of self-diagnosis. SOLUTION: This physical quantity detecting device has a period for detecting changes in capacity and a period for displacing a movable electrode and applies a periodically changing signal between the movable electrode 2d and each fixed electrode 3, 4. In the period for detecting the changes in capacity, a C-V conversion circuit 21 outputs a voltage matching a change in a differential capacity consisting of the movable electrode 2d and the fixed electrodes 3, 4 and acceleration is detected. In the period for displacing the movable electrode, during self-diagnosis a voltage to be applied to the non-inversion input terminal of an operational amplifier 21a in the C-V conversion circuit 21 is changed from V/2 to V1 to impart false acceleration to the movable electrode 2d. |
