| 摘要 |
PURPOSE:To control an accurate displacement by containing a pressure reducing element in a vessel, displacing a vessel in response to the displacement of an element, detecting the displacement by a thin film strain gauge formed in the vessel, and applying a corresponding voltage. CONSTITUTION:A piezoelectric element 1 is press-fitted in contact with upper and lower parts in a vessel 10 of constantly elastic material of sectional port shape, and a predetermined pressure is applied to right and left supporting plates in a state that a voltage is not applied to the element 1. First thin film strain gauges 11 are provided at right and left sides of the supporting plates along the longitudinal direction of maximum sensitivity when the element 1 is displaced in a direction of an arrow, and second thin film strain gauges 12 are formed at upper and lower sides along the lateral direction in which the displacement is not almost sensed. The gauges 11, 12 are oppositely disposed to be associated in a bridge, output difference is detected by an amplifier 30, and the applying voltage to the element 1 is so controlled that the output of the amplifier 20 coincides with the set input by an amplifier 21. According to the configuration, with an electric signal responsive to the displacement of the element 1 measured in advance is used as a set value, and a corresponding voltage is applied to the element to remove the influence of a hysteresis, and the displacement can be accurately controlled.
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