Development of Self-oscillating Ultrasonic Micromotor

Abstract

We have focused on and developed an ultrasonic motor to be used as a microactuator in place of an electromagnetic motor. We have established a new ultrasonic motor principle which allows a self-oscillating circuit to be easily constructed and simplifies the drive circuit. We have also simplified the motor structure, which is easy to mass-produce and miniaturize. We applied this motor, with a diameter of 8 mm and a thickness of 4.5 mm, to a vibration alarm in a watch at a price similar to conventional watches. Additionally, we further miniaturized this motor to 4.5 mm in diameter and 2.5 mm in thickness and confirmed the possibility and effectiveness as a microactuator. This ultrasonic micromotor is expected to be a new drive source in a broad range of fields.