Patent ID: 6586860
Filing Date: 2003-07-01
Classification: H02N

Abstract:
An ultrasonic motor comprising:a piezoelectric element having a plurality of driving electrodes and a common electrode; a vibrating body driven by the piezoelectric element to undergo vibration in response to a signal applied across the driving electrodes and the common electrode of the piezoelectric element; a moving body driven by vibration of the vibrating body; a self-excited oscillating circuit having an amplifier circuit for amplifying an output signal of the piezoelectric element and feeding back the amplified output signal as a driving signal to the driving electrodes of the piezoelectric element to cause self-excited oscillation of the vibrating body; a common connecting point provided between the amplifier circuit and the plurality of driving electrodes of the piezoelectric element for connecting the plurality of driving electrodes to one point so that all of the driving electrodes are simultaneously driven; and an inverter provided between the common connecting point and at least one of the driving electrodes of the piezoelectric element for selectively inverting the phase of the driving signal supplied to the at least one driving electrode to control a direction of movement of the moving body.