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:
Aug. 20, 2002
Filed:
Nov. 06, 2000
Michael Byrne, Limerick, IE;
James Duignan, Limerick, IE;
Keith Fawcett, Limerick, IE;
Fergus Flynn, Newmarket-on-Fergus, IE;
Michael Guinee, Limerick, IE;
E.I. Technology Limited, Shannon, IE;
Abstract
A smoke alarm device has an ASIC ( ) with an integrated photo detector ( ) and control circuit. The photo detector output is compared every ten seconds with an alarm threshold level in a comparator circuit ( ), with a sensitivity-decrease threshold in a comparator circuit ( ), and with a sensitivity-increase threshold in a comparator circuit ( ). A logic block ( ) causes sensitivity to be increased or decreased in which decreases take place at intervals of six hours and increases take place after 40 secs. The logic block ( ) provides for least sensitivity at power-up with rapid increases to the appropriate level according to the level of back-scatter caused by dust contamination. The logic block ( ) maintains a high signal on an interconnect terminal ( ) for four seconds after a test button ( ) is pressed so that a maintenance person can hear remote interconnected devices after the local device has stopped sounding. The logic block ( ) also stores a memory flag when is goes into alarm mode and modulates the horn at a different frequency at the next testing to indicate that it has historically sensed smoke since last tested.