Electro-optic smoke detector
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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Abstract
An electro-optic smoke detector is described which has an improved smoke chamber and detector construction to enhance the detector sensitivity in general and its response to small smoke particles in particular.
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Citations
8 Claims
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1. Optical smoke detector apparatus comprising:
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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. - View Dependent Claims (2, 3, 4)
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5. An improved smoke sensing chamber for an optical smoke detector apparatus comprising:
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a smoke sensing chamber; light source means in said apparatus; mirror means in said chamber; light detector means surrounding said mirror means in said chamber; means focussing the light from said source onto said mirror means and not onto said surrounding light detector means, whereby the light directed on said mirror means is reflected generally back toward said source without falling on said light detector means; and whereby in the presence of smoke in said chamber the focussed light and the reflected light is scattered by the smoke particles and the scattered light falls on the light detector means to indicate the presence of said smoke. - View Dependent Claims (6, 7, 8)
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Specification