| 摘要 |
PURPOSE:To prevent an electrostrictive plate from deteriorating in its polarization by inserting a voltage limiter to a drive input circuit, and forming it with a pnpn element circuit which is turned ON by the prescribed voltage. CONSTITUTION:A piezoelectric actuator is composed of isogonic polarization type bimorph element 1, a drive input circuit 2, a polarization switching circuit 3, a constant-voltage circuit 4, a controller 5 and a DC power source 6. In this case, voltage limiters 21, 22 are provided, the other ends are commonly connected, connected to one input terminal A of the input circuit 2, and the connecting points of high resistors 23, 24 is connected to the other input terminal B of the input circuit 2. The circuits 21, 22 are formed by connecting in parallel Zener diodes 211, 221 with thyristors 212, 222 of pnpn element, a high voltage is applied to electrostrictive plates H1, H2 when the polarity of the applied voltage is switched, and then gradually lowered. Thus, strong generated force can be obtained at polarity switching time, and sufficient displacement can be obtained. |
