Self-diagnostic smoke detector
US5523743A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 13, 1995 |
| Grant date | Jun 4, 1996 |
| Priority date | — |
| Expiry date | Apr 13, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B29/145
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
The present invention provides a method for detecting whether an alarm circuit is operating outside its sensitivity range, the alarm circuit having a background signal and a preset alarm threshold signal. The method involves: a) multiplying the background signal by a first gain factor to produce a first test signal; b) comparing the first test signal against an alarm threshold signal; c) multiplying the background signal by a second gain factor less than the first gain factor to produce a second test signal; and d) comparing the second test signal against the alarm threshold signal. The alarm circuit is operating outside its sensitivity range when the first test signal is less than the alarm threshold signal or the second test signal is greater than the alarm threshold signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.