PURPOSE: To achieve a higher impact resistance, by providing a protective circuit adapted to protect a vibrating circuit from abnormally high voltage and large current by discharging between a vibrating electrode and the vibrating circuit to protect the vibrating circuit even on possible transient contact between a vibration and the vibrating electrode.
CONSTITUTION: To prevent a possible damage to vibrating circuits 11 and 12 by abnormal voltage or large current such as those during the discharge period or the like accidently overlapping terminals 21 and 22, protective circuits 51 and 52 are inserted respectively. The protective circuits 51 and 52 comprises a resistor 511 and a high-speed diode 512. The protective circuit 52 is so arranged to operate against negative abnormal voltage by reversing the direction of diode of the protective circuit 51. In the case of a discharge, an abnormal voltage may overlap terminals 21 and 22 but the protective circuits 51 and 52 function to instantaneously absorb positive abnormal voltage and negative abnormal voltage to protect the vibrating circuits 11 and 12 against abnormal voltages.
HAMAMOTO NOBUO
KAWAMURA YOSHIO
SATO KAZUO
