Patent ID: 7247970

Claim:
A drive method for a piezoelectric actuator comprising: preparing a frequency control device of a piezoelectric actuator and said piezoelectric actuator, said piezoelectric actuator having a vibrating body being vibrated by the application of a drive signal with a specific frequency to a piezoelectric element, and a contact section being provided on said vibrating body and pressed against a driven object, and said frequency control device having a first variable frequency oscillator being configured to output a clock signal and to vary a clock signal frequency, a voltage adjustment circuit having an up-down counter to input said clock signal outputted from said first variable frequency oscillator, and a digital/analog converter to set a voltage value of output voltage on the basis of a counter value of said up-down counter, a second variable frequency oscillator being configured to vary an output signal frequency by voltage outputted from said voltage adjustment circuit, and a control circuit, said control circuit having a sweep direction control unit to select a sweep direction by switching clock signal input to up input or down input of said up-down counter, a sweep speed control unit to control sweep speed by varying said clock signal frequency outputted from said first variable frequency oscillator, and a frequency resolution control unit to control frequency resolution by setting the bit number of said up-down counter; supplying said drive signal to said piezoelectric element at a frequency being swept within a specific range; detecting a detection signal indicating a vibrating state of said vibrating body; and controlling a sweep speed of said frequency of said drive signal supplied to said piezoelectric element based on said detection signal.