Patent ID: 6441534
Filing Date: 2002-08-27
Classification: H02N

Abstract:
An ultrasonic motor comprising:a self-excited oscillation circuit comprised of a vibrating body having a piezoelectric element and an amplifier circuit for amplifying an output signal of the piezoelectric element for oscillating the vibrating body in a predetermined natural mode; a moving body disposed in contact with the vibrating body and driven in response to oscillation of the vibrating body; and a control signal generating circuit for outputting to the self-excited oscillation circuit a drive command signal or a stop command signal to bring the self-excited oscillation circuit into a drive state to drive the moving body or a stop state, respectively; wherein the control signal generating circuit is set so that a length of the drive command signal is a time period required for the self-excited oscillation circuit to start oscillating at a frequency corresponding to a given frequency for driving the moving body.