Building alarm system with synchronized strobes
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Accused Products
Abstract
In a building fire alarm system, the light strobes of a network of strobes are synchronized to flash simultaneously. Each strobe has a charging circuit to charge a capacitor which discharges through a flash tube. Once a capacitor is charged, the charging circuit is disabled. A synchronization pulse is applied through common power lines to trigger discharge of each strobe capacitor through the flash tube followed by recharging of the capacitor.
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Citations
53 Claims
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1. -48. (canceled)
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49. A control circuit for synchronously firing at a predetermined rate a plurality of flash units of a fire alarm warning system, said system including a fire alarm control panel having a power supply for the system, comprising:
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a two-conductor power distribution line to which each of said plurality of flash units is connected through a respective sync trigger circuit;
a sync control circuit having input terminals connected to said system power supply and output terminals connected to said power distribution line;
said sync control circuit further including (1) first controlled switching means electrically connected between said input terminals and said output terminals for supplying power from said system power supply to said plurality of flash units and (2) means connected to said input terminals and receiving power from said system power supply 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 to produce sync signals at said predetermined rate; and
said sync signals being operative to simultaneously actuate the respective sync trigger circuits of said flash units and cause said strobe alarm units to flash at said predetermined rate.
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50. An alarm unit for use in an alarm system, comprising:
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means for connection to a two-conductor power distribution line as the sole source of power for the alarm unit;
means for producing a visual alarm signal, the visual alarm signal producing means comprising a first capacitor connected in parallel with a flash tube, first switch means for connecting and disconnecting an inductor across said two-conductor power distribution line to store energy in said inductor during periods of connection of said first switch means and causing energy to be transferred from said inductor to said capacitor during periods of disconnection of said first switch means, and means for repetitively cycling said first switch means between open and closed states;
means for detecting interruptions of power to the alarm unit over said power distribution line; and
means for triggering the visual alarm signal producing means in response to the detection of a first interruption of power of a first predetermined duration of time. - View Dependent Claims (51)
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52. A sync control circuit for use in an alarm system having (1) a fire alarm control panel with a power source, (2) a plurality of alarm units, and (3) a two-conductor power distribution line as the sole source of power for said plurality of alarm units, each of said alarm units comprising means for producing a visual alarm signal and means for triggering said visual alarm signal producing means in synchronization with all other alarm units upon receiving a sync pulse, the sync control circuit comprising:
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a set of input terminals and a set of output terminals, the set of input terminals receiving power from said power source which is to be supplied to the alarm units over said two-conductor line;
a switching means connected between said set of input terminals and said set of output terminals; and
control means for actuating the switching means to interrupt power to the alarm units at a predetermined rate for producing a sync pulse to cause each alarm unit to produce a visual alarm signal simultaneously with the other alarm units in the system. - View Dependent Claims (53)
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Specification