Patent ID: 6809485
Filing Date: 2004-10-26
Classification: H02P

Abstract:
A driving device for an oscillatory actuator, comprising:a controlled oscillator; a frequency dividing circuit that divides the frequency of an output from said controlled oscillator; a waveform shaping circuit that shapes an waveform output from said frequency dividing circuit; an intermittent driving circuit that intermittently and differentially drives said oscillatory actuator on the basis of an output of said waveform shaping circuit; an electromotive force detecting circuit that detects a polarity of an electromotive force generated across a driving terminal of said oscillatory actuator; a polarity reversing circuit that controls and reverses the polarity of an output signal of said electromotive force detecting circuit synchronously with the driving period of said intermittent driving circuit; and an extracting circuit that extracts an output signal of said polarity reversing circuit only at a time that said intermittent driving circuit is not operating, said polarity reversing circuit and said extracting circuit being connected between an output of said electromotive force detecting circuit and a control input of said controlled oscillator wherein by selecting an oscillation frequency for said controlled oscillator on the basis of an extracted output logic level of said electromotive force detecting circuit, the frequency of an intermittent driving output is automatically pulled to a neighborhood of a self-resonance frequency of said oscillatory actuator.