Ultrasonic motor and electronic apparatus equipped with ultrasonic motor

Abstract

An ultrasonic motor comprises a traveling wave generating circuit for generating a traveling wave signal effective to drive a moving member, and a standing wave generating circuit for generating at least one type of standing wave signal effective to stop movement of the moving member. A switching circuit is receptive of the traveling wave signal and the standing wave signal for selecting one of the traveling wave and the standing wave signals as an output signal. A piezoelectric vibrator drive circuit is receptive of the output signal of the switching circuit for producing a high-frequency voltage signal. At least one piezoelectric vibrator includes an electrode pattern and is adapted to be driven by the voltage signal to undergo expansion and compression. A vibrating member is fixed to the piezoelectric vibrator and vibrationally driven by the expansion and compression movement of the piezoelectric vibrator. A moving member is disposed on the vibrating member to be frictionally driven by expansion and compression movement of the piezoelectric vibrator. The moving member is provided with a plurality of load portions for stopping movement of the moving member, the load portions being greater in number than the number of nodes of the standing wave.