| 摘要 |
PURPOSE:To always securely provide desired displacement of a piezoelectric element regardless of hysteresis and ageing change of the element by providing a displacement detector at the movable member of the piezoelectric element and controlling the applied voltage based upon the comparison of the electric amount of the detector with standard electric amount. CONSTITUTION:A plurality of planar piezoelectric porcelains 1 are alternatively laminated in reverse direction of polarization to form a piezoelectric laminate P, which is secured at one end through an insulating plate 2a to a stationary member 3 and at the other end through an insulating plate 2b to a movable member 4. A displacement detector 5 is so arranged in the vicinity of the member 4 for detecting the elongated displacement occurred at the end 4a of the member 4 when high voltage is applied to the laminate P and contracted displacement taken place when reverse polarity voltage is applied thereto in this configuration, and a projection 4b munted at the member 4 is inserted between the inductance detectors 5a and 5b forming the detector 5. Thus, the displacement of the member 4 is detected to control the high voltage power supply 9 for applying high voltage through an electric converter 6, a standard displacement setting potentiometer 7 and a comparator 8 to the laminate P. |
