Hitachi, Ltd.

Hitachi Media Electronics Co., Ltd.

Muneo Chiba

Kazuo Kato

Takashi Sase

Tomohiko Douken

Kikuo Tomita

Kazuyoshi Takizawa

Shuzo Oshima

An electrostrictive revolution type ultrasonic motor includes a piezoelectric ceramic disk shaped stator and a rotor. The piezoelectric ceramic disk shaped stator has an eccentric movement via excitation by two phase pulse like voltage. The rotor is fitted around the circumference of the stator and is transmitted by a rotating torque due to the eccentric movement via frictional contact therebetween. The rotor is formed of a plastic material by injection molding to achieve a reduction of a size variation of the rotor and a stable contact with the stator. A high and stable rotating torque is thereby obtained with a reduced production cost. Further, a driving device for the ultrasonic motor which varies the frequency of a voltage applied to the ultrasonic motor in a stepped manner discriminates the magnitude of the corresponding motor currents and drives the ultrasonic motor with the frequency which causes the maximum motor current. In this manner, a simple structured and low cost driving device which operates at a high speed and at a high resolution with a high efficiency is achieved.

Ultrasonic motor and driving for the ultrasonic motor

Growing community of inventors

Chigasaki, Japan

Muneo Chiba