| 摘要 |
PROBLEM TO BE SOLVED: To provide a capacitance type semiconductor acceleration sensor capable of effectively self diagnosing, without providing any separate self diagnosing electrode. SOLUTION: An acceleration sensor 100 has a beam 22 displaceable in a direction perpendicular to the beam length, and a periodically varying signal is applied between a movable electrode 24 and fixed electrodes 32, 42 integrated with the beam 22 to output a voltage corresponding to the differential capacitance change between the capacitances CS1, CS2 between these electrodes, thereby detecting the acceleration. The signal for detecting the acceleration is switched to a self diagnosing signal and it is applied to cause the movable electrode 24 to be quasi-accelerated. The beam width W1 of the movable electrode 24 in the displacing direction is set nearly equal to the beam width W2 of the beam 22 in the displacing direction and the rigidity of the movable electrode 24 in the displacement direction is set greater than that of the beam 22 in the displacing direction. |
