Communications: electrical – Condition responsive indicating system – With particular system function
Reexamination Certificate
1998-03-25
2001-11-06
Pope, Daryl (Department: 2632)
Communications: electrical
Condition responsive indicating system
With particular system function
C340S517000, C340S506000, C340S538000, C340S533000, C340S535000
Reexamination Certificate
active
06313744
ABSTRACT:
BACKGROUND OF THE INVENTION
Typical building fire alarm systems include a number of fire detectors positioned throughout a building. Signals from those detectors are monitored by a system controller which, upon sensing an alarm condition, sounds audible alarms throughout the building. Flashing light strobes may also be positioned throughout the building to provide a visual alarm indication. A number of audible alarms and strobes, generally referred to as notification appliances, are typically connected across common power lines on a notification circuit. A first polarity DC voltage may be applied across the notification circuit in a supervisory mode of operation. In the supervisory mode, rectifiers at the notification appliances are reverse biased so that the alarms are not energized, but current flows through the power lines of the notification circuit to an end of line resistor and back so that the condition of those lines can be monitored. With an alarm condition, the polarity of the voltage applied across the power lines is reversed to energize all notification appliances on the notification circuit.
An alternate method of supervising audible alarms and strobes is to use addressable appliances as disclosed in U.S. Pat. Nos. 4,796,025 (Farley et al.); 5,155,468 (Stanley et al.); and 5,173,683 (Brighenti et al.). Each addressable appliance has an individual address and is polled by the system controller to determine if it is present. When an appliance receives its associated address, its response to the poll indicates that the communication path between the appliance and the system controller is operational.
During installation of a building fire alarm system, the system controller is programmed to associate each fire detector input signal with one or more notification appliance circuits (in the case of non-addressable appliances) or individual notification appliances (in the case of addressable notification appliances). In a conventional system installation, programming can be verified by initiating an alarm input (e.g., smoke detector, pull station) to cause an alarm notification through the associated audible and visible notification appliances. A technician can then verify the programming by walking through the building and checking that the appropriate audible and visible notification appliances have been operated. Once the conventional building fire alarm system becomes operational, testing of individual notification appliances is accomplished by causing all of the appliances on a notification circuit to operate, followed again by a technician walking through the building to check that all of the appliances are functioning.
SUMMARY OF THE INVENTION
The conventional methods of verifying system installation and troubleshooting notification appliances can be very disruptive, especially in buildings such as hospitals which do not typically have an unoccupied period during which testing can be performed.
In accordance with the present invention, notification appliances connected to a system controller are provided, with each appliance having an alarm indicator such as an audible alarm or strobe, and a status indicator, such as an LED. The status indicator provides for system test modes that are not disruptive to building occupants. Accordingly, to test the programming of an alarm system, the system controller selects which notification appliances to operate in response to a test alarm input which is specific to one or more alarm condition detectors and communicates to each selected appliance an instruction to operate its associated status indicator without operating its associated alarm indicator. A technician can then check that the correct appliances have been operated, thus verifying the programming without disturbing the occupants of the building by activating the appliance. For notification appliances having both an audible alarm and a strobe, the status indicator can be operated at different rates to distinguish whether the audible alarm, strobe, or both would normally have been energized.
In a troubleshooting mode where there has been a supervision failure, the system controller selects to operate the status indicator of those notification appliances which respond to polling. This allows a technician to locate for troubleshooting purposes only those appliances having a nonoperating status indicator.
According to another aspect of the invention, an alarm system includes plural notification appliances that each have an alarm indicator, a microprocessor and a locally-activated switch. The microprocessor is programmed to transmit a first message in response to a manual activation of the switch. A system controller connected to the notification appliances receives the first message from the activated appliance and in response transmits a second message instructing the appliance to operate its associated alarm indicator for a test time interval. In a preferred embodiment, the locally-activated switch is a magnetic-field sensitive switch. In an alternate embodiment, the switch comprises an infrared sensor and switch circuitry. Each notification appliance further includes a status indicator which the microprocessor is programmed to operate in response to the switch activation for a second test time interval.
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Capowski Anthony J.
Furtado Michael A.
Maier, Jr. Paul H.
Hamilton Brook Smith & Reynolds P.C.
Pope Daryl
Simplex Time Recorder Company
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