An Ultrasonic Motor is a motor with a brand new concept; it does not require coils or magnets. Its driving force is an ultrasonic vibrator. Our laboratory carries out various researches with a traveling wave type ultrasonic motor. A traveling wave type ultrasonic motor is composed of a stator and a rotor. When AC voltages are applied to the piezoelectric elements bonded to the stator, the stator generates the traveling wave and it results in the generation of the elliptical motion. In order to drive the motor, the AC voltage is applied to the piezoelectric element with the ultrasonic frequency (20~100 kHz). At this time, if two standing waves with phase differences are applied, the standing waves will overlap, and generate a traveling wave on the stator surface. At one point of the stator surface generates an elliptic motion. The rotor, compressed at the stator, is moved by the elliptic motion.

Fig.1 principle of the ultrasonic motor

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