Fabrication and characteristics of impact type ultrasonic motor

The design and characteristics of novel ultrasonic motor, which is applicable to automatic focus and optical zoom operation of lens system for cellular phone and PDA, are investigated. The motor has a small-scale size and simple structure, which is composed of tungsten plate, multi-layers piezoelectric ceramic block and carbon fiber rod. As the experimental results, the motor can move linearly in forward and backward movement with changing waveform of applied voltage. The testing motor of 2 mm diameter and 7.9 mm length exhibits maximum speed of 6 mm/s and consumption power of 0.1 W, driven at saw tooth wave of 10 Vp–p, frequency of 61 kHz, and mechanical load of 2 g. Considering its performance such as low power consumption, low operating voltage and simple structure, the proposed motor may be applicable to automatic focus and optical zoom operation of lens system in the mobile instruments.