A SELF-OSCILLATION-TYPE ULTRASONIC LINEAR-ACTUATOR

A cylindrical piezoelectric ceramic vibrator with two half-moon shaped electrodes on a flat surface is described as a key device for constru cting a linear actuator. The unidirectional mechanical force, arising from two coupled vibration modes, on the side surface of the ceramic c olumn plays the role of a stator for the actuator operation. A practic al power-feeding circuit composed of the piezoelectric ceramic column with three electrode terminals and a transistor for power amplificatio n is demonstrated successfully under a stable. continuous actuator ope ration. The size of the ceramic vibrator used for the present linear a ctuator is 10 mm in diameter and 10 mm in length. The directionality o f linear actuator operation is changeable. The response time to the st eady state from zero is on the order of ms.