This paper aims at obtaining a magnified output displacement by using characteristics of elastic deformation of a leaf spring. As well known, when a small input displacement is given at one of the two fixed ends, a large displacement can be observed at the midpoint of the leaf spring. In this study, the small input displacement is provided by rotating a screw thread contacted with a slider, constituting the fixed end, or is provided by actuating a piezo-electronics element. The authors made it clear by theory, FEM and experiment that the thinner and the longer the leaf spring is, the higher the magnification factor becomes and furthermore, that the smaller the input displacement is, the higher the magnification factor is brought.
We developed high speed stepping motor of 2 poles constructed by an automatic control system of the rotating rotor. It made us possible to make a vibration-motor driven at a stable high speed with low power and a watch-motor capable of clockwise and anticlockwise rotation at a stable high speed.
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.
We developed a display device for motion picture. The display elements of each dot are composed of rotors of small stepping motors and are able to display one of four colors such as cyan, magenta, white and yellow. The stators, coils and magnetic circuits are arranged compactly in the cylindrical display element. The display elements are able to rotate and stop rapidly because they have small inertia and are well fitted to drive pulses. We made two display devices with the dot pitches of 6 mm and 20 mm, and they can display 30 frames and 15 frames of picturs per second, respectively.
We developed "Triple Sensor Watch" which senses ambient temperature with thermistor, altitude and atmospheric pressure with silicon piezoresistive pressure sensor and earth's magnetic field with magnetoresistive device. In order to realize "Triple Sensor Watch", we designed analog circuits around these sensors to be integrated into microprocessor in CMOS-LSI.