Synchronization circuit for visual/audio alarms
US5400009A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 7, 1993 |
| Grant date | Mar 21, 1995 |
| Priority date | — |
| Expiry date | Oct 7, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/34
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A strobe alarm system which includes multiple normally self-timed strobe circuits connected in a common loop to a fire alarm control panel, and a sync control circuit, which may be incorporated in the fire alarm control panel, for causing the strobes to flash in synchronism at a predetermined rate which will insure that a person viewing the multiple strobes would not see flash rates higher than the predetermined synchronized rate, which is preferably less than five flashes per second. The sync control circuit does not interfere with the supervision functions of the alarm system, and when an alarm condition is present it supplies power to the strobe circuits which it then interrupts once every flash cycle to cause a sync trigger circuit in each strobe to fire its flashtube, and to reset the internal timer of each strobe to ready it for arrival of the next sync signal. Each strobe circuit in the loop includes a resettable timer for recycling its own flash unit in a non-synchronous fail-safe mode in case the sync signal should fail to appear within a finite period following the last previous flash. That is, normally the strobes are all fired at the same time in response to sync signal…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.