自励駆動型超音波モータを用いた振動アラーム付AQの開発

概要

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We have set our sights on and developed an ultrasonic micro-motor to be used as an actuator in watches. We succeeded in developing the world's smallest ultrasonic micro-motor with a diameter of 10mm and a thickness of 5mm in 1991 and applied it to a watch(Cal.9M21A). We used thc progressive wave method , the most popular method, in this motor. But the circuit in this type of the motor is very complex because it needs two signals with different periodical phases and a control circuit to maintain the stability of the motor against the change of temperature and voltage. This time, we have further miniaturized the ultrasonic micro-motor to 8mm in diameter and 4.5mm in thickness, at the same time we simplified the motor-structure and drive circuit by using self-oscillating circuit. Due to the complexity of making a self-oscillating circuit for the progressive wave method, this time we used the standing wave method. We have succeeded in applying this motor to a vibration alarm in our new analog quartz watches at a price similar to the conventional watches. The alarm can be set easily to thc desired time by turning the dial near the 4 o'clock position. In future, we are planning on trying to miniaturize the motor, increase torque, decrease the current, and apply it to many functions in watches.
社団法人日本時計学会の論文
1997-12-20