The Design and Characteristics of a Novel Ultrasonic Motor

In this paper, the design and characteristics of a novel ultrasonic motor which is applicable to optical zoom or auto focusing operation of lens system for mobile phone are investigated. Its design and simulation of performances are carried out by FEM (Finite Element Method) commercial software. The shape of the motor is like square without one side, which is able to insert optical lens. Two sheets of piezoelectric ceramic are fixed to both sides of the two legs of an elastic body, respectively. To drive the ultrasonic motor, the voltage is applied to the two sheets of piezoelectric ceramic bonded to one leg. The rotation direction can be easily changed by switching the applied voltage to the piezoelectric sheets bonded to the other legs. The proto type of motor is fabricated and its outer size is 10*10*2 mm3 including the camera lens of which the diameter is 7.5 mm. Its power consumption is about 0.3 W and the rotation speed is adjustable from 10 to 200 rpm according to the applied voltage.