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:
Nov. 08, 1983
Filed:
May. 15, 1981
Applicant:
Inventors:
Robert L Farquhar, Woodley, GB;
David N Ball, Langley, GB;
Assignee:
Graviner Limited, , GB;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G08B / ;
U.S. Cl.
CPC ...
340578 ; 250339 ; 250340 ; 340587 ; 340600 ;
Abstract
Photoelectric type detector responds to radiation in a narrow wavelength band characteristic of a fire or explosion, and a slow-response detector, such as a thermopile, is sensitive to radiation in a different narrow wavelength band centered at, for example, 4.4 microns, again characteristic of the same fire or explosion. The electrical outputs of the detectors are fed into a ratio unit which causes an AND gate to produce a fire or explosion indicating output only when the ratio of the output of the thermopile detector to the output of the other detector exceeds a predetermined value.