| 摘要 |
The present invention relates to a vibration wave motor which is configured to prevent abnormal noise from being produced at a start time or a stop time and, more particularly, to a control device for a vibration wave motor which obtains a driving force by applying a periodic voltage to an electro-mechanical energy conversion element so as to generate in a vibration member thereof a plurality of standing waves having a phase difference therebetween, the plurality of standing waves being synthesized to generate a driving vibration in the vibration member. The control device comprises a frequency control circuit which varies a frequency of the periodic voltage and, when a driving force of the vibration wave motor is to be stopped, varies the periodic voltage so as to achieve a predetermined frequency at which a rotational speed of the vibration wave motor becomes zero, and a voltage control circuit which gradually lowers a voltage level of the periodic voltage to a predetermined voltage and then, after the frequency control circuit varies the frequency so as to achieve the predetermined frequency, stops energization of the vibration wave motor.
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