Alarm system
US4144528A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 29, 1976 |
| Grant date | Mar 13, 1979 |
| Priority date | — |
| Expiry date | Dec 29, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B19/00
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An alarm system includes: (1) a central station having power generating means and alarm registering means, and (2) a plurality of alarm-producing systems in locations remote from the central system, each electrically connected to the central station through a single pair of conductors, and each including circuitry for producing up to eight separate alarm conditions as the power generating means alternately impresses a first predetermined DC voltage on each pair of conductors simultaneously, then interrupts voltage to all conductors simultaneously, impresses a second predetermined DC voltage only on the first of each pair of conductors simultaneously, and again interrupts voltage to all conductors simultaneously.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.