Photoelectric smoke sensor

Abstract

Abstract PURPOSE:To improve sensitivity by providing a projector, a reflecting plate for a light beam, and a photodetector for light scattered by smoke in an optical path, and by outputting a detection signal when the output voltage of the scattered-light detector increases above a prescribed value. CONSTITUTION:A light beam 2 emitted from a projector 1 is reflected more than once by a couple of reflecting plats 3 and 4. A photodetector 5 photodetects scattered light from its circumference to convert the detection result into a voltage which corresponds to the amount of photodetection, and the output voltage of the photodetector 5 is supplied to a detecting circuit 6. The detecting circuit 6, when the input voltage exceeds a certain value, outputs a detection signal. The photodetector 5 receives all of the light beams 2-1, 2-2, 2-3, 2-4, etc., scattered by striking smoke in passing by it, so the amount of photodetection increases to improve sensitivity.

Inventors

• 👤 Katsura Yamamoto

Bibliographic Details