PURPOSE: To provide a semiconductor acceleration sensor of which formation process is simple, which does not require an electrode used exclusively for self-diagnosis and of which utilization efficiency is good.
CONSTITUTION: The rear surface of an overlapped body 13 composed of a silicon sheet is used as a movable electrode 14. On the other hand, a fixed electrode in a state facing the movable electrode is arranged in a prescribed part on the surface of a flat rectangular sheet which is arranged at the lower part of the overlapped body and whose indication in the figure has been omitted. At this time, the fixed electrode is constituted of a first fixed electrode 15a and a second fixed electrode 15b which have been divided. The movable electrode and the first fixed electrode are connected directly to a capacity detection circuit 16, the second fixed electrode is connected to the capacity detection circuit via a switch 17, and the individual electrodes 14, 15a, 15b are used for acceleration detection. On the other hand, when the switch is changed over, the second fixed electrode can be connected to a variable battery device 18, a voltage is applied to the second fixed electrode from the battery in a diagnostic operation, an electrostatic attractive force is generated and the overlapped body is deformed.
OBA MASATOSHI
UMEDA HIDENOBU
MORITA YOSHIYUKI
HOSOYA KATSUMI
SHIIKI MASAKAZU
HARUYAMA TAKAYUKI
UNO KEISUKE
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