Fire detector for discriminating smoke and flame based on optically measured distance
US5225810A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 20, 1991 |
| Grant date | Jul 6, 1993 |
| Priority date | — |
| Expiry date | Aug 20, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S17/10
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A fire detection apparatus discriminates white smoke, black smoke and flame in a protected area based on changing characteristics of optically measured distances. The apparatus includes a distance meter having a light emitter for emitting a pulse of light energy towards a reference object, such as a distant wall, and a light detector for receiving the pulse of light energy reflected from the reference object or any intervening object. A distance to the reference object or the intervening object is determined based on the lapse of time from the emission to the detection of the pulse of light energy. White smoke is deemed detected when the distance measured is less than a reference difference and is substantially free of fluctuations. Black smoke is detected when the distance measured is more than the reference distance and is also substantially free of fluctuations. Flame is detected when the distances measured differ from the reference distance and fluctuates substantially.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.