| 摘要 |
A driving device for an ultrasonic wave motor has a limit detecting circuit for detecting that the drive voltage for the ultrasonic wave motor has reached a limit, and, in response, a drive voltage limiting circuit controls the drive voltage so as not to go beyond the limit value. Such control is conducted on the voltage. or frequency of a signal for driving the ultrasonic wave motor. In another aspect of the invention, a drive state detecting circuit detects the drive state of the ultrasonic wave motor, and a drive frequency (or voltage) setting circuit controls the frequency (or voltage) of a signal for driving the ultrasonic wave motor so as to attain the maximum efficiency in the motor, based on the output of the drive state detecting circuit.
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