Optics: measuring and testing – By particle light scattering – With photocell detection
Patent
1977-06-10
1979-09-04
Clark, Conrad J.
Optics: measuring and testing
By particle light scattering
With photocell detection
250574, 340630, G01N 2100
Patent
active
041666984
ABSTRACT:
One type of smoke detector has a housing forming a dark chamber into which light is directed on a path viewed by a smoke sensing photocell. Smoke in the viewed light path scatters light to the cell exciting the cell to alarm state if the smoke is of density predetermined to be dangerous. The detector is tested for its ability to respond to the predetermined smoke density by means of an external owner-operated button. Depressing the button turns a lever or bell crank which intercepts the light path in the chamber and scatters light to one or more large areas within the dark chamber. These secondary areas in turn rescatter the scattered light to the photocell simulating smoke and exciting the cell to alarm state.
The primary light scattering surface of the bell crank and the areas of secondary light scatter are large enough that the light ultimately scattered to the photocell is equivalent to that scattered by smoke of the predetermined density.
REFERENCES:
patent: 2877453 (1959-03-01), Mendenhall, Jr.
patent: 3598492 (1971-08-01), Fruengel
patent: 3868184 (1975-02-01), Marsocci
patent: 4025915 (1977-05-01), Enemark
patent: 4053785 (1977-10-01), Lee et al.
American District Telegraph Company
Clark Conrad J.
Grover James H.
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