Sharp Kabushiki Kaisha Corporation

Fenwal Controls of Japan, Ltd.

Kohichiroh Sugimoto

In a smoke sensor, a first light-receiving element which receives light from a light-emitting element and is disposed in a position where the quantity of received light changes according to a density of smoke and a second light-receiving element which monitors the quantity of light of the light-emitting element are arranged symmetrically with respect to the light-emitting element. Furthermore, a signal from the first light-receiving element and a signal from the second light-receiving element are amplified by an identical amplifier circuit. In a microcomputer, the density of smoke is computed based on a difference between an output obtained by amplifying an output of the first light-receiving element with the amplifier circuit and an output obtained by amplifying an output of the second light-receiving element with the amplifier circuit.

Smoke sensor and electronic equipment

An embodiment of the present invention comprises: at least one light-emitting portion that emits light; a plurality of light-receiving portions, disposed at intervals in the passing direction of the moving object, that receive and detect light emitted from the light-emitting portion and reflected by the moving object; a holding portion that holds information indicating the passing direction of the moving object corresponding to a change in the detection outputs of the light-receiving portions occurring when the light-receiving portions receive the light reflected by the moving object; and a determination portion that determines the passing of the moving object based on the passing direction of the moving object as held by the holding portion and the detection outputs of the light-receiving portions occurring when the light-receiving portions receive the light reflected by the next moving object.

Moving object detection photointerrupter having a determination of passing of the moving object based on its passing direction and the detection information of the next moving object and electric device using the same

A light-receiving amplifier circuit of the present invention includes: a first preamplifier circuit to which a light-receiving element is connected; a second preamplifier circuit which is the same type as the first preamplifier circuit and which is apart from the light-receiving element; and a differential amplifier circuit for amplifying output voltage differential between the preamplifier circuits, wherein each of the first preamplifier circuit includes an amplifier and first and second plural feedback resistors, each of which resistors has an end commonly connected to an input terminal of the amplifier; an amplification factor of the differential amplifier circuit is less than one; and the first preamplifier circuit includes an output voltage expanding circuit which is connected to (i) another end of the first feedback resistors in the first preamplifier circuit and (ii) an output terminal of the amplifier, and which circuit is for expanding an output voltage range from the amplifier and supplying the expanded output voltage range to the differential amplifier circuit. This configuration provides a light-receiving circuit which is capable of reducing heat noise to prevent deterioration of the S/N ratio, while avoiding narrowing down of an output voltage range.

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Nara, Japan

Kohichiroh Sugimoto