Dowa Mining Co., Ltd.

Kenichi Iyama

Toru Hosaka

An optical detector or an optically detecting apparatus comprises divider means for outputting not only a light source flash signal which divides an oscillation signal with frequency higher than that of an expected disturbance light but also an operating time signal divided into a divided ratio a plurality of times longer than the first mentioned divided ratio, shift means for successively shifting a light signal receptive to a light receptive element by a clock input synchronous with the oscillation signal during the time when the operating time signal is inputted, and means for outputting a light detection signal when the shift output corresponds to the set value as compared with one another and terminating the light detection signal when the operating time signal is terminated. Further, the optical detector includes invisible light sources and light receptive elements disposed in a plurality of pairs, and means for indexing only one pair, updating the index when said operating time signal is terminated, then changing over the light source flash signal in an inputtable condition to only the invisible light source indexed by the index means and only the index light receptive element in an enable condition.

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Chiba, Japan

Kenichi Iyama