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:
May. 29, 2001
Filed:
Jul. 12, 1999
Applicant:
Inventors:
Stephen George Porter, Northants, GB;
Bryan Lorrain Humphreys Wilson, Northants, GB;
Stephen Hollock, Lechlade, GB;
Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G08B 2/900 ;
U.S. Cl.
CPC ...
G08B 2/900 ;
Abstract
When an array of thermal detectors with appropriate read-out means is used as a sensor to detect events such as intruders or fire, it may be disabled accidentally or deliberately by placing a mask over the array to shield it from the scene. The act of placing a mask over the array induces a simultaneous transient signal from all of the detectors, or at least a majority of the detectors, and is followed by a period when those detectors give rise only background noise or clutter. The characteristics of these signals is used to generate a warning signal to indicate that the sensor has been disabled.