US 5,705,979 A · Smoke detector/alarm panel interface unit

Abstract

An interface unit interposed between a central alarm panel and a string of smoke detectors interconnected by a three-wire bus. Two wires of the bus carry AC power and the third wire is an interunit signalling wire. When an individual detector senses a smoke condition, it places a voltage on the signalling wire. The other detectors sound their alarms upon detecting this voltage. The interface unit senses this voltage and notifies the central alarm panel, with the sensing circuitry having a variable high input impedance and being powered solely from the signalling wire. The interface unit includes a test button which, when actuated, disables communications to the central alarm panel for a predetermined period of time. During this time, the interface unit places a periodic signal on the signalling wire, which causes all of the detectors to "beep" while that signal is present. The interface unit also senses the absence of AC power on the bus for notifying the alarm panel of such AC power failure. Audible alarms are energized upon sensing either smoke detection or AC power failure, with these audible alarms being distinguishable one from the other.

Claims25

Dependent claims

An interface unit adapted to be interposed between at least one alarm device and an alarm panel:

the at least one alarm device being coupled to a signalling wire and being arranged to provide a predetermined voltage on the signalling wire in response to the sensing of alarm condition:
the at least one alarm device being further arranged to provide an audible signal in response to sensing the predetermined voltage on the signalling wire, the interface unit comprising;
connection means for providing a connection to said signalling wire;
sensing means having an input coupled to said connection means and responsive to the presence of said predetermined voltage on said signalling wire for providing a predetermined electrical current at an output of said sensing means, said sensing means being isolated from any source of voltage other than said signalling wire:
and
alarm notification means coupled to the output of sensing means and responsive to said predetermined electrical current for providing an alarm condition signal to said alarm panel, said alarm notification means being electrically isolated from said sensing means:
wherein said sensing means includes a light emitting diode and said alarm notification means includes a phototransistor in light communication with said light emitting diode.

4 more elements

An interface unit adapted to be interposed between at least one alarm device and an alarm panel, the at least one alarm device being coupled to a signalling wire and being arranged to provide a predetermined voltage on the signalling wire in response to the sensing of an alarm condition, the at least one alarm device being further arranged to provide an audible signal in response to sensing the predetermined voltage on the signalling wire, the interface unit comprising:

connection means for providing a connection to said signalling wire:
sensing means having an input coupled to said connection means and responsive to the presence of said predetermined voltage on said signalling wire for providing a predetermined electrical current at an output of said sensing means, said sensing means being isolated from any source of voltage other than said signalling wire:
alarm notification means coupled to the output of said sensing means and responsive to said predetermined electrical current for providing an alarm condition signal to said alarm panel;
test switch means operable into a test state for initiating a test of the at least one alarm device;
voltage providing means responsive to the test switch means being in the test state for applying the predetermined voltage to the signalling wire;
and
inhibit means responsive to the test switch means being in the test state for inhibiting operation of the alarm notification means.

4 more elements

connection means for providing a connection to said signalling wire:
sensing means having an input coupled to said connection means and responsive to the presence of said predetermined voltage on said signalling wire for providing a predetermined electrical current at an output of said sensing means, said sensing means being isolated from any source of voltage other than said signalling wire;
alarm notification means coupled to the output of said sensing means and responsive to said predetermined electrical current for providing an alarm condition signal to said alarm panel;
AC monitor means coupled to the two AC wires of the bus for providing a first signal when AC power is not present on the bus;
AC failure detection means responsive to said first signal for providing an AC failure signal;
and
power failure notification means responsive to said AC failure signal for providing a power failure signal to said alarm panel.

4 more elements

An interface unit interposed between at least one alarm device and an alarm panel, the interface unit and the at least one alarm device being interconnected by a three wire bus wherein two of the bus wires are adapted for connection to a source of AC power for powering the at least one alarm device and the third of the bus wires is a signalling wire, the at least one alarm device being arranged to provide a predetermined voltage on the signalling wire in response to the sensing of an alarm condition, the at least one alarm device being further arranged to monitor the voltage level of the signalling wire and generate an audible signal upon sensing the predetermined voltage on the signalling wire, the interface unit comprising:

alarm notification means for monitoring the voltage on the signalling wire and responsive to the presence of the predetermined voltage on the signalling wire for providing an alarm condition signal to the alarm panel indicative of the sensing of the alarm condition by the at least one alarm device;
test switch means operable into a test state for initiating a test of the at least one alarm device;
voltage providing means responsive to the test switch means being in the test state for applying the predetermined voltage to the signalling wire;
and
inhibit means responsive to the test switch means being in the test state for inhibiting operation of the alarm notification means.

2 more elements

Dependencies are inferred from the claim text.

Smoke detector/alarm panel interface unit

Life of this patent

Smoke detector/alarm panel interface unit

Life of this patent

Abstract

Claims25