| 摘要 |
PURPOSE:To accurately control the displacement of an electrostrictive element only by open loop control of an applied voltage by applying the maximum available voltage of the element more than once from zero volt in an impulse state, and then applying again a set voltage corresponding to a necessary mechanical displacement amount from zero volt. CONSTITUTION:After the maximum available voltage Em of an electrostrictive element is applied in an impulse state more than once from zero volt, a set voltage E1 corresponding to a necessary mechanical displacement amount delta1 is again applied from zero volt. When a voltage is not applied for a long time, the element displaces along an initial profile as shown by applying a voltage, and even if the voltage is again set to zero, the displacement does not return to zero, but becomes an initial position delta0. When it is returned to zero after the maximum voltage Em is again applied then, the displacement at this time is recovered substantially at the position delta0. Then, to obtain the mechanical displacement (target displacement delta1) of the necessary element, with the position delta0. as a reference a voltage E2 which is slightly larger than the set voltage E1 is applied for a time t (several msec-0.1 sec), it is then returned to E1.
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