Automatically supervised alarm system
US4241335A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 26, 1978 |
| Grant date | Dec 23, 1980 |
| Priority date | — |
| Expiry date | Jun 26, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/1672
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An alarm system including an alarm which is actuated when a sensor such as a microphone detects an emergency condition. In one embodiment the output of the microphone is fed through a filter circuit tuned to frequencies characteristic of breaking glass. In conventional systems failure of the microphone may remain undetected but in the system of the present invention an alarm is instituted when the sensor detects any emergency signals and when the sensor fails to detect a reference signal. The reference signal is produced at regular intervals but the alarm instituting means includes a delay and is operable to switch off the reference signal within the delay period to avoid false alarms.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.