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:
Jul. 03, 2001
Filed:
Mar. 19, 1999
Bernard Etienne Henri Laluvein, Eastcote, GB;
Paul Basham, High Wycombe, GB;
Thorn Security Limited, Middlesex, GB;
Abstract
There is described a detector which is suitable for use as a fire detector. The detector has two channels which allow for discrimination between energy received from a fire and a “false fire”. False fires are sometimes detected as a result of radiation from a so called “cold”, black body radiation source which flickers at a frequency of between 1 and 20 Hz. In the past, these gave rise to false alarms being triggered. The invention overcomes the problem by having a notch filter which when used in combination with another filter, ensures that detected radiation at, or around, 4.3 &mgr;m is transmitted to a sensor. A processor then compares the received value with a value computed by interpolating between signals received from two other channels. If a threshold value is exceeded an alarm is triggered. The invention thus overcomes disadvantages with prior art systems as signals from cold black body sources are rejected as false.