Dual scattering-type smoke detector with cross-checking
US4769550A · kind A · utility
17Cited by
3References
14Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jul 29, 1987 |
| Grant date | Sep 6, 1988 |
| Priority date | — |
| Expiry date | Jul 29, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B17/113
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Two photoelectric smoke detectors are arranged so that each smoke detector in turn verifies operation of the other smoke detector. Each smoke detector has a light source and a photodetector which is not directly illuminated by the light source. A smoke detection signal is issued when light from such a light source is scattered to the respective photodetector. The two smoke detectors are arranged so that a small amount of light from each light source illuminates the photodetector of the other smoke detector. A fault signal is issued when such a photodetector is not illuminated by the other light source.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.