The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 06, 1990
Filed:
Dec. 24, 1986
James A Best, Netcong, NJ (US);
Irving L Ellner, Hopatcong, NJ (US);
Cerberus AG, , CH;
Abstract
A focused beam of light from a light source is directed into a closed smoke chamber, having inlets for admitting smoke particles, toward a reflector which reflects and refocuses the beam back into the light source, the direct beam and the reflected beam passing through a test zone within the chamber. In the event that smoke particles enter the test zone, the direct and reflected beams strike and bounce off of those particles to produce scattered radiation that will be picked up and detected by a light responsive sensor to generate an alarm signal. By closely controlling, rather than baffling the light, optimum operation is obtained, efficiency is enhanced and false alarms are minimized. Additionally, to prevent any stray light from bouncing off of undesired dirt and dust in the chamber and being received by the light sensor, resulting in a false alarm, surfaces of the chamber are provided with parallel grooves for accumulating that dirt and dust, and the light sensor field of view is focused on an attenuating light trap. Stray light impinging on the grooved surfaces becomes attenuated and absorbed so there will be no reflections, and light entering the light trap is reduced to a negligible level.