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Electro-optic smoke detector

  • US 4,230,950 A
  • Filed: 05/16/1979
  • Issued: 10/28/1980
  • Est. Priority Date: 05/16/1979
  • Status: Expired due to Term
First Claim
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1. Optical smoke detector apparatus comprising:

  • a smoke sensing chamber having air inlet and outlet means;

    an optical sensor in said chamber having a face comprising a light receiving portion and a light reflecting portion, said light receiving portion being of a relatively large area with respect to said light reflecting portion;

    light source means in said apparatus;

    means directing the light from said source substantially onto said light reflecting portion and minimally onto said light receiving portion, whereby the light directed on said light reflecting portion is reflected generally back towards said source without falling on said light receiving portion;

    and whereby in the presence of smoke in said chamber light is scattered thereby, and falls on said light receiving portion to indicate the presence of said smoke.

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