Abstract:
An emergency lighting unit includes a lamp, a backup battery, and controller and a network interface. The controller connects the backup battery to the lamp upon detection of an emergency condition and loss of main power. The network interface interfaces with and receives commands via a fire alarm network. Each emergency lighting unit has a unique identifier with respect to the fire alarm network.

Description:
RELATED APPLICATION(S)  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/502,338, filed Sep. 12, 2003. The entire teachings of the above application(s) are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Emergency lighting systems are dependent on battery backup to provide egress lighting when AC power has failed. Presently, emergency lighting units are provided with manual test capability. Typically, these units provide a test switch, or other manual means for initiating a test, which is held in the “ON” position for 90 seconds each month. The battery is tested by applying a load for the duration in which the switch is pressed.  
         [0003]     This method of battery test is inadequate to properly measure actual battery capacity. For example, a given unit loads the battery with 1 Ampere during the 90 second load test. This is the same as the emergency lighting load. This load represents only a 0.025 Ampere-hour (Ah) discharge, and is not really an adequate representation of battery condition, since the actual system will be required to provide 90 minutes standby. Additionally, an annual test is intended to be done in order to measure actual battery capacity by fully discharging the batteries. This test requires significant labor, since a building can have many emergency lighting components.  
         [0004]     U.S. Pat. No. 6,538,568, to Conley III, entitled “EMERGENCY LIGHTING REMOTE MONITORING AND CONTROL SYSTEM” teaches an emergency lighting unit identified by unique ID numbers. The unit communcates via wireless means with a central controller. Various commands from the central controller may include turning the lamp on and off, requesting a status, or initiating a battery voltage and lamp current tests.  
       SUMMARY OF THE INVENTION  
       [0005]     Integration of Emergency Lighting Individual Addressable Modules (ELIAMs) according to an embodiment of the present invention with a fire alarm system allows for better monitoring at lower service cost. Automation of the test cycle is provided. Backup of a depleted battery following the test is provided by a signaling line circuit (SLC). This enables continuous monitoring of battery condition. Required monthly testing may be eliminated. Annual test requirements can be met monthly. A system trouble condition and annunciation via the fire alarm network or other means can provide notice that a specific battery requires replacement.  
         [0006]     Integration of emergency lighting functions with a fire alarm system may be advantageous because the fire alarm system provides a higher level of monitoring than is typically provided by an emergency lighting system.  
         [0007]     An ELIAM according to an embodiment of the present invention communicates with a fire alarm control panel using a network, such as a pre-existing fire alarm network. The ELIAM monitors battery capacity by fully discharging a battery at regular intervals,  
         [0008]     An ELIAM discharges the local battery on command from the system controller. The ELIAM monitors battery voltage and current during the discharge, thus providing an actual measurement of battery capacity.  
         [0009]     An emergency lighting unit according to an embodiment of the present invention includes a lamp, a backup battery, and controller and a network interface. The controller connects the backup battery to the lamp upon detection of an emergency condition and loss of main power. The network interface interfaces with and receives commands via a fire alarm network. Each emergency lighting unit has a unique identifier with respect to the fire alarm network.  
         [0010]     The controller, upon receiving a test command, causes the backup battery to discharge, while sensing the battery&#39;s state and forwarding battery state information via the network interface to a network or system controller, such as a fire alarm control panel. The battery state information may include an indication of at least one of: voltage across the battery and current draw from the battery.  
         [0011]     The backup battery can be discharged through the light source, or alternatively, through a ballast load. Discharge may be for a preset period, or may be controlled by start and end commands received from the network controller. Discharge of the backup battery can also be terminated if the battery&#39;s terminal voltage drops below a predetermined threshold, in which case a trouble indication may be sent to the network controller. Troubles may be indicated when battery capacity is not adequate. For example, detection of no or low current during discharge may be interpreted to mean that the lamp is defective.  
         [0012]     In at least one embodiment, backup power is delivered via the network while the battery is being discharged. Such backup power may be supplied by the network controller.  
         [0013]     A test log may be maintained at the fire alarm control panel (FACP) or other system controller or network controller, to record the batter capacity of each emergency lighting battery. In one embodiment, the emergency lighting unit is capable of maintaining at least a limited test log and reporting the log to the network controller upon a command.  
         [0014]     The emergency lighting unit may be one of plural similar units connected to the network, which each is assigned a unique address. The plural units can be tested, for example, on a periodic rotating schedule. In addition, there can be plural fire alarm appliances, such as smoke detectors, fire detectors, pull stations, intrusion detectors, motion sensors, and audible alarms connected to the network, where each device has been assigned a unique address.  
         [0015]     In one embodiment, the emergency lighting unit inhibits the light source from turning on during an emergency condition that would normally cause the light source to be on. This may be, for example, in response to a command from a network controller, and the light source may be inhibited from turning on upon certain conditions; for example, if ambient light is adequate in the vicinity of the unit, that is, sensed ambient light has reached or passed a predetermined threshold; or if no movement has been detected in the vicinity of the unit within some time frame.  
         [0016]     In at least one embodiment, a light sensor verifies that the lamp is activated. If the lamp appears not to be activated, the controller reports the detected fault via the network interface.  
         [0017]     A method for testing emergency lighting according the present invention comprises: providing a backup battery, such that upon loss of main power, the backup battery supplies power to a lamp; upon receiving a test command from a fire alarm control panel (FACP) via a fire alarm network, discharging the backup battery; and reporting information about the backup battery acquired during discharge to the FACP. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.  
         [0019]      FIG. 1  is a schematic diagram illustrating an exemplary fire alarm network.  
         [0020]      FIG. 2  is a schematic diagram illustrating a system embodying the present invention.  
         [0021]      FIG. 3A  is a block diagram illustrating a first embodiment of the present invention ELIAM.  
         [0022]      FIG. 3B  is a block diagram of an alternative embodiment in which the ELIAM includes a lamp. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     A description of preferred embodiments of the invention follows.  
         [0024]      FIG. 1  is a schematic diagram illustrating an exemplary fire alarm network. The system includes one or more notification appliance circuits (NACs), i.e., networks  16 , having alarm condition detectors D and alarm notification appliances A. Alternatively, the detectors and notification appliances may be on separate networks. The detectors D are monitored by a system controller  14 . When an alarm condition is sensed, the system controller  14  signals the alarm to the appropriate notification appliances through one or more networks  16 . Notification appliances may include, for example, a visual alarm (strobe), an audible alarm (horn), a speaker, or a combination thereof.  
         [0025]     Although not necessary for carrying out the invention, as shown, all of the notification appliances in a network are coupled across a pair of power lines  18  and  20  that advantageously also carry communications between the system controller  14  and the notification appliances A.  
         [0026]     Emergency lighting components according to an embodiment of the present invention may be integrated into a networked fire alarm system such as that illustrated in  FIG. 1 . Each emergency lighting component is an addressable module within the fire alarm system and communicates with a system controller over an addressable loop, or signaling line circuit (SLC), i.e., a fire alarm network.  
         [0027]     The emergency lighting component is referred to hereafter as an Emergency Lighting Individual Addressable Module (ELIAM). According to one embodiment of the present invention, ELIAMs co-exist with other fire alarm peripherals, e.g., smoke detectors, pull stations, etc.  
         [0028]     Each SLC is rated to allow the monitor and control a certain number of addressable modules. For example, in one embodiment, one SLC may allow  250  modules on a single SLC, thirty of which may be ELIAMS. A system may have multiple SLCs. (For example, the system of  FIG. 1  has two SLCs  16 .) A particular SLC may be designed to support a given number of ELIAMs, which may represent full or partial SLC capacity.  
         [0029]     As an example, for a SLC that supports 250 devices, thirty of which may be ELIAMS, a monthly discharge test on each device can be performed. Each day, the system controller may command a single ELIAM to perform a discharge test. The SLC provides backup during the period when the battery is discharged in case of an AC failure during the battery test. The ELIAM converts the network power to the standby source in case of AC failure. Over the course of a month, all thirty devices on the SLC are tested completely. This exceeds the required test schedule, and provides early notification of a defective or depleted battery.  
         [0030]     As the battery is discharged, the system records the discharge current and the battery voltage. Should the battery reach end of capacity, for example, 1.75V per cell with SLA batteries, discharge will cease. The discharge period can be set as desired or as required by local code. For example, many systems require 90-minute backup. In this case, the ELIAM would operate the emergency lights (or, alternately a ballast load simulating the emergency lights) for 90 minutes. If the terminal voltage (1.75V/cell in the example above) is reached before the 90 minutes, a trouble indication may be given.  
         [0031]     The system may also verify that the emergency lamp is drawing the expected current draw. For example, if an ELIAM measures no or lower than expected current, it is likely that the emergency lamp is defective or that the bulb has burned out.  
         [0032]      FIG. 2  is a schematic diagram illustrating a system embodying the present invention. For illustrative purposes only, just one SLC  16  is shown, and the single line represents the two wires  18  and  20  of  FIG. 1 .  
         [0033]     A breakout panel  30  supplies power over power line  32  to one or more lights  34 , some of which may be designated for emergency lighting. According to an embodiment of the present invention, an ELIAM  36  is attached between the lighting power line  32  and a light  34 . The fire alarm network is extended to the ELIAM via connectino  38 . The ELIAM thus appears to the control panel (system controller)  14  as another network appliance, and can be controlled by, and report to, the control panel  14 .  
         [0034]      FIG. 3A  is a block diagram illustrating a first embodiment of the present invention ELIAM. Power is received through power line  32  and is normally routed to power lamp  34 . In the event of an AC power loss, a controller  42  causes the lamp  34  to be powered from the backup battery  40 .  
         [0035]     A network interface  44  connects the unit to the fire alarm network  38 . Upon receiving a command via the network interface  44  from the system controller  14  ( FIG. 2 ), the ELIAM controller  42  disconnects the lamp  34  from the power line  32  and instead causes the lamp  34  to be powered from the backup battery  40 .  
         [0036]     Thus, upon a command to test the backup battery  40 , the battery  40  is discharged through the lamp  34 . The battery voltage or current draw may be monitored by the controller  42  and the resulting battery or lamp (no current would imply a faulty lamp) information can then be transmitted to the system controller  14 .  
         [0037]     Alternatively, rather than discharging the battery  40  through the lamp  34 , the battery  40  could be discharged through a dummy load (not shown).  
         [0038]     Note that in the embodiment of  FIG. 3A , the lamp  34  is external to the ELIAM  36 . For example, a pre-existing lamp  34  may be disconnected from a power source with the ELIAM  36  of  FIG. 3A  being inserted between the power line  32  and the lamp  34 .  
         [0039]      FIG. 3B  is a block diagram of an alternative embodiment in which the ELIAM  36  includes a lamp  34 .  
         [0040]     In another embodiment, the fire alarm system can be used to extend battery standby duration. For example, a motion sensor or system of motion sensors can be used to activate emergency lights only when lighting is needed. The sensor is monitored by the fire alarm system, and the fire alarm system commands the ELIAM to activate its light when motion is detected. This conserves available battery capacity for when it is needed rather than consuming capacity when nobody is walking through an area.  
         [0041]     Furthermore, a photo sensor could determine if ambient light is sufficient. For example, if a particular corridor is near a window, and daylight is adequate, ELIAMs in the corridor may be controlled to preserve battery capacity.  
         [0042]     Similiary, a light sensor may be used to indicate that an emergency light is activated. A properly placed sensor could determine that the lamp actually is energized and providing emergency lighting. Failure of the lamp could thus be reported as a trouble condition.  
         [0043]     Since the ELIAM is identified by its system address, a custom label, such as a textual description, can be assigned to the point. This custom label and the system address identify the device and location that require service.  
         [0044]     Alternatively, the system can provide the same features and operation described above using a suitably designed notification appliance circuit (NAC) or auxiliary power output point. The required measurement capabilities are described above. In this case, the backup power for the emergency lighting system may come from the fire alarm panel or from a NAC power extender.  
         [0045]     Finally, the system provides addressable control of the emergency lighting system, which may be useful during a fire.  
         [0046]     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood ty those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.