| 摘要 |
<p>In a driving device for an ultransonic motor which includes a stator for generating a travelling vibration wave in an elastic member by the excitation of a piezoelectric member and a rotor brought into contact with the stator by means of a pressurization means, the rotor being driven by the travelling vibration wave, a drive signal which drives the motor is supplied to the motor through an induction element. A phase difference between signals input to and output from the induction element is measured, and drive of the ultrasonic motor is controlled using the obtained value. The device further comprising a phase difference limitation detection means for detecting that the measured phase difference has reached a preset value wherein said drive control means controls the frequency of the drive voltage signal such that the phase difference decreases to a value smaller than the preset value when the phase difference is equal to or larger than the preset value. <IMAGE></p> |
