Detecting the presence of a fire
Patent 5612537 Issued on March 18, 1997. Estimated Expiration Date: 
September 1, 2014. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
September 1, 2014. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesOptical fire or explosion detection system and method Method for detecting a fire condition Patent #: 5373159 InventorsAssigneeApplicationNo. 298307 filed on 09/01/1994US Classes:250/339.15Sensing flame or explosionExaminersPrimary: Hannaher, ConstantineAttorney, Agent or FirmInternational ClassG08B 017/12Foreign Application Priority Data1993-09-03 GBAbstractApparatus for detecting the presence of a fire includes a pair of detectors for radiation characteristic of a fire, e.g. at 4.3 microns, and a further detector for radiation characteristic of a black body, e.g. at 3.8 microns. Filters select the detector output components at flame flicker frequencies. The filtered outputs of the detector pair are cross-correlated to produce a relatively noise-free signal. This signal is divided by a factor obtained by cross-correlating the further detector filtered output with the average of the detector pair filtered outputs. The result of the division is applied to a threshold-responsive circuit. Thus the relatively noise-free signal is effectively subjected to a threshold which is proportional to the degree of similarity between the variations with time of the output signal of the further detector and the output signals of the detector pair.Field of SearchSensing flame or explosion | |
