Monitoring system
US4567471A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 8, 1983 |
| Grant date | Jan 28, 1986 |
| Priority date | — |
| Expiry date | Aug 8, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B26/006
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A monitoring system for a protection loop that has a plurality of switches in series utilizes modules with inexpensive diodes and resistors, and is conveniently and easily added to existing burglar alarm circuits and loops. A monitoring module that includes a diode and a paralleled resistor is connected across each switch. First and second interrogating signals are alternately applied to the protection loop. First comparator circuit means provides an output in response to each first interrogating signal when one of the monitored switches in the protection loop is open as indicated by the response of the module resistors; and second comparator circuit means provides an output in response to each second interrogating signal when more than one of the monitored switches in the protection loop is open as indicated by the response of the module diodes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.