Tsubakimoto Chain Company

Katsuhiko Asada

Tadashi Morita

Atsuhiko Tamaki

A voltage detecting circuit is capable of detecting the voltage to be detected at high precision, is small in size, and is low in manufacturing cost. A first photo coupler and a second photo coupler are interposed between voltage input terminals to which the voltage to be detected is applied. The photo coupler has light emitting elements connected parallel reversely, first voltage generator for generating a voltage depending on the photo detector side currents of the first photo coupler and second photo coupler, a differential amplifier whose one input terminal receives the voltage generated by the first voltage generator. A third photo coupler and a fourth photo coupler having light emitting elements are connected parallel reversely for receiving the output current of the differential amplifier, and a second voltage generator for generating a voltage corresponding to the photo detector side currents of the third photo coupler and fourth photo coupler. The voltage generated by the second voltage generator is fed into the other input terminal of the differential amplifier, so that the voltage depending on the light emitting element side currents of the third photo coupler and fourth photo coupler is matched with the voltage fed into the voltage input terminals.

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Fukui, Japan

Katsuhiko Asada