| 摘要 |
PURPOSE: To improve the measurement accuracy of a sensor by automatically compensating the action of an external parameter by using small part of the sensor itself. CONSTITUTION: A sensor 300 is provided with two piezoelectric layers 30 and 31 which are biased in the opposite directions, one central electrode 32, and two outside electrodes 34 and 35. The electrodes 34 and 35 are connected in parallel with the (+) input of an amplifier 310 and the electrode 32 is connected to the (-) input of the amplifier 310. In order to form a capacitor for feedback, small parts 36 and 37 which are isolated from other parts are respectively formed on the layers 30 and 31. The parts 36 and 37 form a small capacitor together with the central electrode 32. The parts 36 and 37 are connected in parallel with the output of the amplifier 310.
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