Murata Manufacturing Co., Ltd.

New Japan Radio Co., Ltd.

Hitoshi Matsuno

Toshio Imanishi

Yasuyuki Endou

A self-oscillating piezoelectric actuator drive circuit includes a integrating circuit; an inverter (INV), inverters (INVand INV) inverting an output signal of the inverter (INV), sense resistors (Rsand Rs) connected to output sides of the inverters (INVand INV), a positive feedback resistor (Rfb) feeding back an output signal of the inverters (INVand INV) to the integrating circuit; and a negative feedback resistor (Rfb) feeding back a voltage generated from the sense resistors (Rsand Rs, Rs&#x3c;Rsin terms of a resistance value) to the integrating circuit. In a startup state, the sense resistor (Rs) and the inverter (INV) are selected, and in an operating state after the startup state, the sense resistor (Rs) and the inverter (INV) are selected.

Piezoelectric actuator drive circuit

An oscillation circuits that provides stable oscillations even when the amount of phase rotation of a piezoelectric resonator is small or fluctuates. The oscillation circuit includes a first amplifier having an input and an output, and a piezoelectric resonator connected between the input and the output of the first amplifier. Moreover, the oscillation circuit feeds, back to the input, a current flowing from the output of the first amplifier to the piezoelectric resonator. The oscillation circuit further includes an alternating-voltage waveform shaping circuit that applies, to the piezoelectric resonator, an alternating-voltage waveform having rising portions sharper than those of a sine wave.

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Nagaokakyo, Japan

Hitoshi Matsuno