| 摘要 |
PURPOSE:To prevent the floating of the output voltage of a bridge circuit even when a cantilevered beam is damaged, by arranging a damage detection conductor to a place where the damage of the cantilevered beam is estimated and providing a circuit for fixing the output voltage of the bridge circuit to a predetermined value when said conductor was disconnected. CONSTITUTION:When a crack is generated in the root of the Si cantilevered beam 4 of a semiconductive acceleration sensor, damage detection conductors 5, 6 are disconnected and the voltage of the gate of a P-channel Tr7 is fallen to Vs through a resistor 9 and, therefore, VGS=VD is formed and Tr7 is turned ON while the bridge output V2 of a bridge circuit formed of piezoelectric resistors 1, 2, 1', 2' is fixed to VD. Because the voltage of an N-channel Tr8 comes to power source voltage VD through a resistor 10, VGS=VD is formed and Tu8 is also turned ON and bridge output V1 is fixed to VS.
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