ULTRASONIC VIBRATOR AND ULTRASONIC MOTOR

PURPOSE:To improve the driving efficiency of an ultrasonic vibrator by a method wherein shearing vibration is generated in a disc type elastic body by employing an electromechanical transducers. CONSTITUTION:An ultrasonic vibrator 20 is constituted of an annular elastic body 21 and piezoelectric elements 22a, 22b, vibrated with lengthwise vibration mode. The size of the elastic body 21 is regulated so as to be vibrated with both ends free primary mode and the vibration thereof is excited by piezoelectric elements 22a, 22b. An ultrasonic motor is constituted of the vibrator 20, a rotor and the like. As a result, the rotor receives a driving force by the vibration of the elastic body 21 and is rotated into one direction only.