US 5,400,009 A · Synchronization circuit for visual/audio alarms

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 signals applied to their sync trigger circuits, but in the event the sync signal is lacking the strobes will continue to flash, each at a rate determined by its internal timer.

Claims24

Dependent claims

A control circuit for synchronously firing at a predetermined rate a plurality of flash units each of which has a timer trigger circuit which normally fires the unit independently of the others, comprising:

a two-conductor power distribution line to which each of a plurality of flash units is connected through a respective timer trigger circuit and through a respective sync trigger circuit connected in parallel with a corresponding timer trigger circuit;
a sync control circuit having input terminals connected across a D.C. power source and output terminals connected to said power distribution line, said sync control circuit comprising:
first controlled switching means connected in series between said input terminals and said output terminals for supplying power from said D.C. power source to said plurality of flash units when and only when an alarm condition is present;
and
timer means connected across said input terminals and receiving power from said D.C. power source when and only when an alarm condition is present, for actuating said first controlled switching means and briefly interrupting the supply of power to said power distribution line at said predetermined rate for producing a sync signal for causing said sync trigger circuits all to simultaneously fire its respective flash unit and for re-setting the timer trigger circuit of each flash unit to enable it to trigger the unit in the event no sync signal arrives after elapse of a predetermined period following the last previous sync signal.

2 more elements

A control system for synchronously firing at a predetermined rate separate groups of flash units, each group for providing visual alarm signals to a given zone and consisting of a plurality of flash units each having an individual timing trigger circuit which normally fires independently of one another, comprising:

for each zone, a two-conductor power distribution line to which each of the plurality of flash units included in the group is connected through a respective timer trigger circuit and a respective sync trigger circuit;
a sync control circuit which includes, for each zone, first controlled switching means having input terminals connected across a D.C. power source and output terminals connected to said power distribution line for supplying power from said source to all of the plurality of flash units in that zone when, and only when, an alarm condition is present in that zone;
and
circuit means including a microcontroller and a power supply therefor connected to the controlled switching means for all of said zones for supplying power to said microcontroller when, and only when, power from said D.C. source is applied to at least one group of flash units, and wherein said microcontroller is coupled to and is programmed to ascertain to which zone or zones power is being supplied and to generate and apply to the first controlled switching means of said powered zone or zones a signal for actuating the same for briefly interrupting the supply of power to the power distribution line connected to the powered zone or zones and producing a sync signal for causing the corresponding sync trigger circuits to fire all of the flash units connected to the powered distribution line or lines, and for re-setting the timer trigger circuit of all of the flash units connected to the powered distribution line or lines for enabling them to trigger a respective flash unit in the event no sync signal arrives after elapse of a predetermined time period following the last previous sync signal.

1 more element

A control system for firing separate groups of flash units sequentially all within a predetermined time interval and each at a predetermined rate, each group for providing visual alarm signals to a given zone and consisting of a plurality of flash units each having an individual timing trigger circuit which normally fires the unit independently of the others, comprising:

for each zone, a two-conductor power distribution line to which each of the plurality of flash units included in the group is connected through a respective timer trigger circuit and a respective sync trigger circuit;
a sync control circuit which includes, for each zone, first controlled switching means having input terminals connected across a D.C. power source and output terminals connected to said two-conductor distribution line for supplying power from said source to all of the plurality of flash units in that zone when, and only when, an alarm condition is present in that zone;
and
circuit means including a microcontroller and a power supply therefor connected to the controlled switching means for all of said zones for supplying power to said microcontroller when, and only when, power from said D.C. source is applied to the flash units associated with at least one zone, and wherein said microcontroller is coupled to and is programmed to ascertain to which zone or zone power is being supplied and to generate and to sequentially apply to the first controlled switching means of each of said zones a pulse signal for actuating the same at staggered times within a predetermined time interval for briefly interrupting the supply of power, if present, to the associated power distribution line and producing a sync signal for causing the corresponding sync trigger circuits to be fired, and for re-setting the timer trigger circuit of all flash units connected to a powered distribution line for enabling them to trigger a respective flash unit in the event no sync signal arrives after elapse of a predetermined time period following the last previous sync signal.

1 more element

Dependencies are inferred from the claim text.

Synchronization circuit for visual/audio alarms

Life of this patent

Synchronization circuit for visual/audio alarms

Life of this patent

Abstract

Claims24