| 摘要 |
PURPOSE:To lead out an electric output by using a piezoelectric disk center fixation type as an oscillation pickup and converting the impedance of the oscillation pickup by an FET. CONSTITUTION:When acceleration is applied to the piezoelectric disk center fixation type oscillation pickup, a voltage is developed and inputted to the gate of the FET 18. The FET 18 has its source grounded through a load 20 and a power source 21 and the signal inputted to the gate appears at an output after being amplified. The output signal has its DC component cut off by a capacitor 22 and only its AC component is outputted. The electrostatic capacity of the piezoelectric disk center fixation type oscillation pickup is tousands of PF and reduced to tens of MOMEGA even in a low frequency range of 0.1-1Hz where the impedance increases within a band (0.1-100Hz) which is used for an acceleration sensor. The piezoelectric disk center type having said feature is utilized and impedance conversion is performed by the FET to obtain an acceleration sensor of simplified constitution which generates a useful electric output.
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