Nagano Keiki Seisakusho, Ltd.

Tetsuo Ogawa

Masakazu Abe

Naohiko Maruno

A gas pressure transducer has a voltage stabilizer for supplying a piezoelectric crystal in a gas with an AC constant-voltage signal corresponding to an applied AC signal and having a constant peak amplitude. An alternating output current from the piezoelectric crystal is converted by a current-to-voltage converter into an AC voltage, which is shifted in phase by a phase shifter so that the impedance of the piezoelectric crystal is minimal or nearly minimal under the resonant condition. The shifted AC voltage is then applied to the voltage stabilizer. The piezoelectric crystal, the voltage stabilizer, the current-to-voltage converter, and the phase shifter jointly constitute a self-excited oscillation loop. Since the amplitude of the AC voltage from the current-to-voltage converter is uniquely dependent on the pressure of the gas, the gas pressure can be known from a DC voltage produced by rectifying the AC voltage.

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Tokyo, Japan

Tetsuo Ogawa