Infra-red flame detector
US4471221A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 16, 1982 |
| Grant date | Sep 11, 1984 |
| Priority date | — |
| Expiry date | Apr 16, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J5/60
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A flame detector arranged to detect flames includes a non-microphonic infra-red sensor having a broad band frequency response. To maximize the sensitivity to radiation from flames in the 4.3 .mu.m solar absorption band a narrow band optical interference filer, transmissive in the band 4.54 .mu.m to 4.38 .mu.m is chosen such that the integrated solar energy transmitted thereby is less than an alarm threshold. A further filter prevents re-radiated heat from the filter reaching the sensor. Another filter prevents radiation of wavelengths less than 4.38 .mu.m from reaching the other filters to reduce heating thereof and also to provide a series of filters to stop direct broad band transmission to the sensor through pin holes in the filters. A signal processor detects flames by virtue of the flame flicker frequencies and includes provision for compensating for the effects of low frequency components on the amplitude of radiation produced by flames.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.