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. 02, 2004
Filed:
Jun. 04, 2003
L. Rodney Bristol, Chalfont, PA (US);
Scott Technologies, Inc., Beachwood, OH (US);
Abstract
A gas detection sensor system including active and reference elements (R , R ) are arranged in a modified bridge circuit ( ) which allows power (V ) to be supplied seperately to the active and reference element (R , R ). A digal processor ( ) monitors the resistances of the elements (R , R ) to control a pulse-width modulator supplying power to the elements, thereby maintaining nearly constant temperatures in the sensor elements (R , R ) and to translate the decrease in power needed to maintain constant temperature on the catalytic element into an output proportional to the concentration of combutible gas in air. The system periodically measures the resistance of the elements (Rref, Rsense) and enables dual operating modes of catalytic-bead detector. One active or reference element (R , R ) can alternately measure low concentrations of combustible gases up to the lower explosive limit (LEL) or measure high concentrations, up to 100% by volume.