| 摘要 |
PURPOSE:To stop a rotor at a high speed with a high positioning accuracy by applying an AC voltage of a resonance frequency to the piezoelectric element and a longitudinal displacement type piezoelectric element of a stator to resonance-drive them in resonance, thereby roughly positioning them, then applying a DC voltage to the elements of the stator to generate a statically twisted distortion. CONSTITUTION:A piezoelectric element 11 is provided at a vibrator 10 through an electrode 12. First, an AC voltage of a resonance frequency of a twisting mode is applied to resonance-drive it, a rotor 5 is similarly rotated at a high speed in cooperation with a longitudinal displacement type piezoelectric element 4 applied by the AC voltage of the resonance frequency to be roughly positioned, then a DC voltage is applied for a predetermined period to generate a statically twisted distortion, the rotor 5 is twist-displaced at a low speed integrally with the element 4 to be accurately positioned. Thus, the resonance drive and the twisted distortion drive are suitably selected to shorten an arriving time to a target rotary angle, thereby improving the positioning accuracy. |
