DRIVE CIRCUIT FOR ULTRASONIC MOTOR

摘要

PURPOSE:To always single-phase drive an ultrasonic motor in the optimum state in a wide range of states. CONSTITUTION:This drive circuit for ultrasonic motors is provided with a deviation detecting means 30 which detects the deviation of an ultrasonic motor 10 from its optimum driven state by detecting changes in the resonance frequency and equivalent resistance of the motor 10 and a deviation correcting means 40 which compensates the temperature change of the binding capacitance of the piezoelectric body of the motor 10 and, at the same time, corrects changes in reactance and equivalent resistance for shifting the phase of an AC voltage applied across the piezoelectric body based on the detected result by the means 30.