Fire alarm apparatus
US4755797A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 11, 1987 |
| Grant date | Jul 5, 1988 |
| Priority date | — |
| Expiry date | Jun 11, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B25/04
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A fire alarm apparatus includes a fire receiver, a pair of transmission lines extending from the fire receiver, a series of nonpolar fire detectors connected to the transmission lines, and a terminating unit, connected to the end terminals of the transmission lines, the terminating unit having an impedance element including a polar element. Each fire detector includes polarity inverting circuitry which includes a limit switch, arranged at a socket portion of the detector, and having a switch lever which is actuated by the detector body engaging with the socket portion; and diodes for inverting the polarity of the pair of transmission lines in synchronism with actuation of the switch lever. The polarity of the transmission lines after a detector is inverted when a detector body is detached from that detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.