Patent ID: 6717330
Filing Date: 2004-04-06
Classification: H02N

Abstract:
An ultrasonic motor comprising:a vibrator to which a piezoelectric body is attached; a moving body that is arranged so as to rotate clockwise or counterclockwise due to the vibration of said vibrator; a pressurizing means that brings said moving body in pressure contact with said vibrator; an electrode that applies a high frequency voltage to said piezoelectric body; an oscillation drive circuit that generates the high frequency voltage; a position sensor that generates a position signal of said moving body; and a control portion that gives a command signal to said oscillation drive circuit and controls the supply of the high frequency voltage to said piezoelectric body to start/stop and rotate forward or backward the motor, in which feedback control is performed by said control portion so that the position of said moving body reaches a desired position while the position signal is compared with the desired position that is inputted in advance, wherein reverse operation is conducted after a stop command retaining time is elapsed since an instant of overshooting.