| 摘要 |
PURPOSE:To remove an output difference dependent upon a direction of rotation by changing a phase difference between an output AC voltage and a driving voltage of an oscillation-detecting electrode to a proper quantity according to the direction of rotation of an oscillatory-wave motor. CONSTITUTION:A diaphragm is provided with A phase driving electrodes A1-A5, B phase driving electrodes B1-B5 and an oscillation-detecting electrode S and piezoelectric elements of these portions are polarization-treated appropriately. Then, a phase difference between an AC voltage applied between these driving electrodes and that detected by the detecting electrode S is varied by phi according to a direction of rotation of a motor. For example, if the detecting electrode S is arranged at the distance theta =315 deg. from the driving electrode A5, a phase difference variation phi should be 90 deg. in order that the diaphragm is placed in the same oscillatory state according to the direction of rotation. As a result, the motor can be driven always at a frequency fr (the mechanical resonance point of an oscillatorywave motor) without changing an oscillator admittance according to the direction of rotation. |
