Driving apparatus for a vibration wave motor

摘要

Disclosed is a driving apparatus for a vibration wave motor in which monitor means is provided for detecting the vibrating state of the vibration wave motor and the difference between the resonance frequency and the frequency of a driving AC signal is detected on the basis of the phase difference between the output signal from the monitor means and the driving AC signal and when the frequency difference is great during the change of the number of revolutions of the motor, the vibration rate of the frequency of the driving AC signal is made greater to improve the responsiveness while, on the other hand, when the frequency difference is small, the variation rate of the frequency of the driving AC signal is made smaller to thereby prevent the occurrence of an unstable operation in which the frequency of the driving AC signal exceeds the resonance frequency to cause sudden stoppage of the motor.