Combined UV/IR flame detection system
US5339070A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 21, 1992 |
| Grant date | Aug 16, 1994 |
| Priority date | — |
| Expiry date | Jul 21, 2012 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23N2223/08
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
A flame detector unit contains a silicon photodiode that is sensitive to UV light waves and two lead selenide photoresistors that are sensitive to IR light waves. The electromagnetic bandwidth of each sensor element is restricted by an optical wave filter to pass photons of certain wavelengths characteristic of hydrocarbon flames and to discriminate against photons of other wavelengths. Signals generated by the IR sensors are in the form of variations in electrical resistance of the sensor elements, which together with a resistor network comprise a bridge circuit which combines the two IR signals so as to discriminate against blackbody radiation sources and provide a signal which is fed through an amplifier. Amplified UV and IR signals are fed to a common analog to digital converter (ADC). Output from the ADC is fed to a digital processor through a notch filter, a cluster of weighted-moving-average filters, and into a threshold comparator/tester. Output from the comparator/tester is fed to a correlator, then through a series of alarm decision making circuits and finally into a series of alarm activation circuits. Stored wave forms relating to profiles of fire characteristics may be…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.