Smoke detector
US4269510A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 9, 1979 |
| Grant date | May 26, 1981 |
| Priority date | — |
| Expiry date | Oct 9, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B17/113
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A smoke detector, especially for a fire alarm, comprising a radiation source possessing a substantially conical ring-shaped radiation characteristic or pattern and a radiation receiver arranged along the axis of the radiation source but externally of the direct radiation. The radiation receiver receives radiation which is scattered by smoke particles within the conical ring-shaped radiation region. In order to reduce the spurious radiation impinging on the radiation receiver the radiation region is bounded by elements located externally of the direct receiving region of the radiation receiver. Web means (which comprise the bounding elements opposite the radiation source) are provided which are specially-shaped to prevent dust from collecting on their radiation receiving surfaces, thereby keeping the smoke detector from becoming increasingly susceptible with time to the triggering of false alarms as the deposition of dust at the inner surface of the fire detector housing increases.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.