Ritsuo Inaba

QUICK RESPONSE IN ROTATION OF ULTRASONIC MOTOR

Very quick response of less than 1 msec rotation is obtained with the development of a small-sized 17 mm diameter ultrasonic motor. This motor is driven by the mechanical vibration excited on the disk plate by piezoelectric ceramics.The observed response time in starting is 0.57 msec and the time in stopping is 0.33 msec at the no-load revolution speed of 700 rpm. These results coincide well with the calculation of the response time based on the experimental results between revolution speed and torque.

An Electrostatic Voltage Sensor Using Surface Acoustic Waves

A compact electrostatic voltage sensor has been developed using a delay line type SAW oscillator. An additional collecting electrode is settled on a surface of a piezoelectric substrate between input and output interdigital transducers. The electrostatic voltage applied to the collecting electrode is detected by a frequency change of the SAW oscillator. Piezoelectric ceramics with d=-42×10-12C/N are used for making the SAW oscillator. The sensitivity achieved is 0.64 Hz/V at oscillation frequency of 23 MHz.

Temperature‐stabilized wide‐band ultrasonic delay line

The low ultrasonic attenuation of fused quartz in the very high frequency range makes it attractive for an ultrasonic delay line. However, the temperature instability restricts its application. A method of stabilizing the delay time based on the properties of a positive temperature coefficient resistor that is used simultaneously as a temperature sensor and a regulator is discussed. This new type of temperature regulator improves the temperature coefficient of the delay time from 85 ppm/°C to 8 ppm/°C. A temperature‐stabilized wide‐band delay line has been fabricated for high definition television. A wide‐band frequency response is obtained by using LiNbO3 transducers and new type bonding adhesion which is stiffened by irradiation of ultraviolet rays. The design of the delay line, which has a midband frequency of 45 MHz, a band width of 50 MHz, and a delay time of 29.55 ms, is presented and experimental results are also presented.

Temperature-Stable SiO2/LiTaO3 Structure for SAW Devices

A temperature dependence of delay time and phase velocity of SAW on a layered structure of SiO2/X-115°Y LiTaO3 was studied. A zero temperature coefficient of delay time was obtained for a normalized SiO2 film thickness of kh1.0 at room temperature. The temperature variation of delay time observed was less than 10 ppm in a temperature range from 0°C to 60°C. The bandpass filter characteristics with a center frequency of 170 MHz were also demonstrated.