LED light fixture for use in public transportation facilities

LED lighting systems, mounting configurations, and light fixtures are disclosed for original and retrofit configurations. Some configurations mount the light fixture with a mounting bracket that allows for the removal and replacement of the light fixture in about the same time as a traditional light bulb change. Some configurations provide for fuse removal and replacement without the need to dismount the light fixture from its mounting bracket or without the need to open the housing of the light fixture to access the fuses. Some configurations use a battery backup system and self-check methods with LED light fixtures configured for public transportation applications.

BACKGROUND OF THE DISCLOSURE

1. Technical Field

The disclosure relates to electric light fixtures and, more particularly, to electric light fixtures using light emitting diodes (LEDs) and having a plurality of power input options. The disclosure particularly relates to LED light fixtures configured for use in public transportation facilities where lighting failures are more critical than other facilities and wherein maintenance time and costs must be minimized. The disclosure also relates to light fixtures usable in public facilities which provide a plurality of power input options and wherein the normal-use light fixture may be used as part of an emergency lighting system drawing power from a battery backup system.

2. Background Information

Essentially all commercial and public buildings and facilities are required by applicable safety codes to have emergency lighting systems that operate during failures of normal utility power supplies. In the past, the emergency lighting systems used lighting sources separate from the normal lighting and each system had independent wiring runs, installation locations, and housings. Newer devices use a single lighting source for both systems. Applicable safety codes dictate the locations, brightnesses, operation, and testing of the emergency lighting systems. Periodic testing of such equipment is required and enforced by a government authority having jurisdiction over the facility.

Many high traffic areas of public transportation facilities are located underground and require light fixtures that operate 24 hours per day, seven days per week, fifty-two weeks per year. These light fixtures must be reliable, easy to replace when burned out, and must be energy efficient. Traditional lighting in public transportation facilities requires bulb changes and typically only provides for a single type of power input. Replacement light fixtures that are easier to maintain and more power efficient are desired by the owners and operators of these facilities. Light fixtures that provide installation flexibility are also desired because the fixtures are often being retrofit into an existing location.

SUMMARY OF THE DISCLOSURE

LED lighting systems, mounting configurations, and light fixtures are provided. Different configurations are disclosed for retrofit applications. Some configurations mount the light fixture with a mounting bracket that allows for the removal and replacement of the light fixture in about the same time as a traditional light bulb change. Some configurations provide for fuse removal and replacement without the need to dismount the light fixture from its mounting bracket or without the need to open the housing of the light fixture to access the fuses.

The disclosure also provides a light fixture with different power input options. The different power options provide installation flexibility. An option is to use multiple power inputs that back each other up if one fails. One disclosed feature is the use of multiple power inputs for the light fixtures to minimize downtime when one of the power sources fails. Up to four electrical inputs may be used with the power inputs being different voltages and different currents. The light fixture can be configured for a high voltage input such as a 600 Volt input power supply and connected to a 600 Volt input, a 110 Volt input and a battery backup power input at the same time. In the event of losing one source, the next takes over until the battery backup is reached.

Another disclosed feature is the use of a battery backup system with the LED light fixture wherein the light fixture and battery power sources encompass a compact package capable of being retrofit into the space of existing light fixtures that do not have the battery backup system. Another disclosed feature is a LED light fixture having desirable lumen distribution, power efficiency, quick maintenance, and a long life cycle.

The light fixture of the disclosure includes a configuration wherein both sides of the power source circuit is fused.

The light fixture of the disclosure provides a configuration having one or more fuses disposed within the enclosure. The fuses may be disposed in a sealed enclosure that also holds the LED power supply or the fuses can be sealed within their own enclosure. Sealed wire pass-through fittings are used for the wiring. The fuses are accessible from the outside of the enclosure so that they may be removed and changed without removing the light fixture from its mount. In one configuration, the fuses are carried in fuse holders that slide out to an exposed position in a movable drawer when the enclosure is opened. This configuration allows the fuses to be removed and replaced without opening the entire housing of the light fixture.

The preceding non-limiting aspects, as well as others, are more particularly described below. A more complete understanding of the processes and equipment can be obtained by reference to the accompanying drawings, which are not intended to indicate relative size and dimensions of the assemblies or components thereof. In those drawings and the description below, like numeric designations refer to components of like function. Specific terms used in that description are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure

Repeated reference numerals refer to similar parts of the disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The disclosure provides LED light fixtures2used as regular-duty light fixtures or as emergency light fixtures that provide light during an outage of normal line power. In some embodiments, light fixture2is used both as a regular-duty light fixture and then as an emergency light fixture during a power outage when the normal line power is not supplied to light fixture2. Some embodiments of light fixture2include on-board battery backup systems while others are used with remote battery backup systems. Each light fixture2disclosed herein includes a LED-powered light engine that produces the light for fixture2and a LED power supply that accepts input electrical power and provides the needed output power specified for the LED light engine. The output power is normally a direct current, low voltage electrical supply. Sealed fuses also may be used between the input line power and the power supply and/or between the power supply and the LED light engine.

Light fixture2is configured for use in public transportation locations where high voltage electricity supplies are available. Each light fixture2disclosed herein is can be configuration accept and use the available high voltage electrical power. In one embodiment, the light fixture2is connected to both the high voltage input as well as a traditional 110-277 Volt line power. In some public transportation facilities, there are multiple 110-277 Volt power lines. Light fixture2can be configured to be connected to each of them for a redundant power input. When multiple 110-277 Volt power lines are available, alternating light fixtures2can be connected to alternating 110-277 Volt power lines. For example, the even numbered light fixtures2can be connected to a 600 Volt power source and a first 110-277 Volt power line and the odd numbered light fixtures can be connected to the 600 Volt power source and a second 110-277 Volt power line. Each light fixture2can then be connected to a remote or self-contained battery backup system. In another configuration, each light fixture2is provided with a power supply that connects to only a single electrical line power source but the light fixture is adapted to use different types of power supplies so the user can configure the light fixtures2for different power sources as desired. These light fixtures also may be connected to battery backup systems and used for emergency lighting situations.

Light fixture2can be configured to have external dimensions to fit within existing wire ways of public transportation facilities to allow light fixtures2to replace existing light fixtures or into the same locations as existing emergency light fixtures. This allows for retrofitting into existing facilities with minimal disruptions. One configuration of light fixture2has an external height dimension (seeFIGS. 2 and 3) of less than four inches (the exemplary configuration has a maximum height of 2.65 inches) so light fixture2may be used in ceiling locations. One configuration of the fixture provides both the light and the emergency battery system within the fixture enclosure. The fixture widths are shown inFIG. 1with the maximum width being defined by the mounting flanges used to secure the fixture in a mounting bracket4that is used to secure the fixture to a structure. This fixture width is 7.625 inches or less.

Light fixture2includes a housing6that defines the mounting flanges8that are received by opposed overhanging fingers of mounting bracket4. The overhanging fingers define channels that receive flanges8. The connection between flange8and bracket4can be frictional, an interference fit, a snap fit, or one that may be secured with separate fasteners. Housing6includes at least one enclosure10that encloses components of fixture2. Housing6also includes a mount12that supports the LEDs14. Mount12may be fabricated from a material that allows it to function as a heat sink. Mount12may include fins to disperse heat from mount12. In the exemplary configuration, light fixture2includes two spaced enclosures10and a pair of spaced LED circuit strips that each carry a plurality of LEDs14. The LEDs14used with fixture2have a minimum combined illumination power to satisfy the emergency lighting requirements of the NFPA Life Safety Code. LEDs may be protected by a lens or a shield. The arrangement of the LEDs in elongated strips is useful for lighting an elongated path of recess. The lens used with fixture2can help distribute the LED light along the desired path.

When used in subway tunnels, mounting bracket4is directly connected to concrete walls with suitable anchors. Mounting bracket4can be made from stainless steel or galzanized steel. Housing6is made from stainless steel, galzanized steel, aluminum, polycarbonate, or a suitable polymer. When made from aluminum, direct contact between stainless steel and aluminum is undesirable especially in hot humid environments because of galvanic corrosion. A spacer5(FIG. 3) may be used to prevent direct contact between the two metals while also providing a shock absorber against the repeated vibration forces to which fixture2is subjected. The spacer5can be made from an insulating material such as a polymer, a rubber, fiberglass, PVC, or other insulating material.

Enclosure10may be substantially hollow to contain a variety of components used with fixture2. In one exemplary configuration, batteries20and components of a self-testing battery backup system are carried within enclosure10. A power supply22also may be carried within enclosure10to provide a self-contained fixture2. In other configurations, the battery backup system and the power supply22can be located in locations remote from housing6. The remote location can be a few feet away or farther such as other locations within the building or facility.

Fixture2includes a light engine that includes two rows of LED boards or strips14disposed above lenses designed to direct light downwardly from enclosure10. Some light is directed through the ends of lenses to help define an elongated light pattern for the pathway. The LEDs meet at least the optical requirements of: end of life—0.25 foot candles across floor (14′ width, 10′ mounting height, 30′ spacing on each side with 15′ stagger)—0.55 lumen maintenance factor; Reflectivity of all surfaces=0.1; Color temperature: 4000K max; CRI: 70 min. The light engine is configured to at least match the light currently provided by the existing incandescent or florescent light bulbs if fixtures2are spaced the same. In one configuration with the spacing described above, the light provided on the ground is uniform both across and along the floor and has no more than a 7:1 ratio between the maximum lit areas and the minimum lit areas. When used as an emergency light fixture, light fixture2can be used to illuminate the paths of egress used during emergency situations. In emergency use, the LEDs are set to output at least one footcandle.

Light fixture2includes at least the light engine and power supply22. When used as part of an emergency lighting system, light fixture2is selectively supplied by a backup power source which is typically one or more batteries20. Batteries20are maintained by a self-testing emergency battery system having a variety of testing and reporting components including a battery charger24.

Light fixture2is configured to be supplied by one of three line power sources in addition to the backup battery power source. In public transportation facilities, electrical power is available from the main power line30which is typically 110V to 277V alternating current. A second source of 110V to 277V alternating current is often provided from a secondary power source32. A third high voltage source of electrical power greater than 277V is the high voltage “third rail” power source34from which train engines drawn power. The third source34can be 450V-1000V direct current or commonly about 600V. Power supply22for the LED light fixture2includes power inputs for each of these three power sources30,32,34such that any of the three sources can be connected or a combination or all of the sources can be connected to allow whichever source is available. A switch is used to allow the user to manually select a power supply or to cause the power supply to automatically switch over to an available power supply in the event of a failure of another. For example, if the light fixture is being powered by the 600 Volt power supply and there is a failure of that power source, the power supply recognizes the voltage drop and automatically switches to the first of the 110-277 Volt power sources. If the first is not available, the power supply looks for the second 110-277 Volt power source. If all three of these power sources are not available, the power supply switches over to the available battery backup power.

If the location of fixture2has all three power supplies available, all three power supplies are connected to power supply22. The 110-277V inputs are kept isolated from the 450-1000 Volt source. In one configuration, the power supply primarily uses the 110-277V input to provide the electrical power for power supply22that supplies the LEDs. If one of the 110-277 Volt inputs is not present, the power supply switches over to the second 110-277 Volt power source and then to the 450-1000 Volt source (typically 600V) to provide the electrical power for power supply22that provides the direct current to the LEDs. Different methods can be used to determine if the 110-277V inputs are present such as a relay, a voltage comparator, a microprocessor etc. In the case of a complete power failure, power supply22is supplied by batteries20. This arrangement minimizes lighting outages.

The multiple power inputs for power supply22provide for a lighting arrangement where alternating fixtures2are connected to alternating power sources. In a corridor having twenty lights, half of them may be connected to first30and third34power supplies with the other half of fixtures2being connected to second32and third34power supplies. This arrangement shields half of the lights from issues with the normal line power supplies.

The LED power supply22converts the high voltage input voltage provided by the third rail34, typically a 450-1000 VDC voltage, into a lower direct current voltage suitable for powering the LEDs14. The external high voltage input voltage includes all input voltages of 277 Volts and higher. Power supply22is preferably flexible enough to accommodate input voltages of between 110-1000 Volts. In addition, power supply22is resistant to voltage spikes of up to 3 kV. Power supply22may be structured to accommodate a 480 Volt three phase supply voltage. Power supply22can provide polarity independence. Power supply22can include a rectifier circuit connected to the external high voltage input voltage. The rectifier circuit provides that polarity independence. In one embodiment, the rectifier circuit is a full bridge rectifier, however, any suitable rectifier circuit may be used. An EMI filter circuit is provided to minimize electromagnetic interference (EMI). The filter circuit is positioned at an output of the rectifier circuit, but may alternatively be positioned at an input to the rectifier circuit. In this case, the EMI filter also provides transient protection. The filter circuit preferably includes capacitive and inductive components commonly used in filters. A converter circuit is connected to an output of the EMI filter circuit and converts the rectified high voltage input voltage into a lower voltage suitable for use in driving the LED circuits to produce light. In one embodiment, the converter circuit is a transformer, however, any suitable voltage converter circuit may be used. The driving voltage provided by the converter circuit is used to drive LEDs14. This drive voltage is preferably provided in a relatively constant manner.

In one embodiment, the drive voltage output from the filter circuit is provided to one of several current control circuits which are, in turn, connected to the LED strips14. That is, a separate current control circuit is provided for each LED strip14in the light fixture2. The current control circuit receives the smooth driving voltage from the filter circuit and provides a driving current to the LEDs. If additional, or fewer, light engines are included in the fixture2, additional or fewer current control circuits may be used. In one exemplary embodiment, the current control circuit is integral with the printed circuit board of each LED strip14. Alternatively, they may be incorporated into power supply22and power supply22may include separate outputs for each light engine to which it is connected.

In one configuration, battery charger24is powered from one of power sources30,32, or with third rail high voltage source34. The voltage/current derived for charging the battery is a separate channel output from either 120-277 Volt input circuit30,32or the 450-1000 Volt input circuit34depending on which is preferable in the application.

In another configuration, power supply22has an output power supply line36for the battery charger24that is used to maintain the charge in batteries30of the battery backup power source. Batteries20supply DC electricity at a voltage as required for use with the LED circuit. Batteries20are configured to power the LED circuit for a minimum of ninety minutes and up to four hours. Batteries may be wired to power supply22or directly to LEDs14.

Battery charger24is used to maintain batteries20in fully charged conditions so they are ready for emergency use at any time. Battery charger24can be powered by any one of the three sources of electric power described above through a supply36. During a power outage, battery power is supplied to power supply22through connection38which is controlled by switch40. Under normal conditions, switch40allows batteries20to be charged by battery charger24. Switch40may be located in a variety of positions and arrangements with respect to power supply22and battery charger24with the position depicted inFIG. 5being exemplary. Battery charger24may be an integral component of power supply22or a separate component. In one configuration, battery charger24is powered by the high voltage third power source34. Battery charger24can have a power input of 600V to allow this high voltage power source34to be used to charge batteries20. The power from high voltage power source34is stepped down to a DC voltage that is used to charge battery20. It may be the same DC voltage of the battery or slightly higher than the DC voltage of the battery depending on the chemistry of the battery. A trickle charging circuit is used to prevent overcharging of the battery. Typically a constant voltage is applied for charging the battery. Depending on the chemistry of the battery the current can either be a constant low current or the system can charge by pulsing between a low current to a higher current. Battery charger24can be a trickle-style charger that maintains a low current direct voltage through batteries20. Battery charger24can thus remain connected to batteries20indefinitely. In some locations and applications, the third rail high voltage source34is less likely to fail than the first30and second32power sources and thus provides more reliability to the system. In other locations and applications, the 110-277V power sources may be less likely to fail. In those instances the 110-277V power source would be used to charge the battery. The power supply may include a circuit that allows it to charge batteries20from with the either 110-277V input30,32or the 450-1000V input34.

Power supply22can be optionally configured to pass MIL-STD-461F testing. Power supply22can be physically located at a separate location from the LEDs and power supply22can be physically located at a separate location from batteries8.

Each battery backup system is periodically monitored for proper function and the results of the monitoring can be displayed locally and/or delivered as data to a remote location. The testing function can be triggered manually by way of push button manually pushed by a user, through the use of a RF trigger signal transmitted from a hand-held RF transmitter, or a magnetic switch that senses a magnetic field brought into close proximity with the switch. Such a magnetic field may be created with a magnetic that is moved into close proximity to the switch by a worker. The magnet can be hand-held or mounted to a wand that allows the worker to reach the light fixture2. The switch can be a mechanical or electrical magnetic field sensing switch. A battery monitoring and emergency power testing circuit can be used to provide the self-testing monitoring function. Testing requirements typically include battery charge, battery discharge, the operation of the transfer switch, and the operation of the lights. The local display may be an indicator light or multiple indicator lights associated with each light fixture2. The state of the indicator light provides information about the status of the system. For example, the indicator light may be lit continuously to indicate proper function, it may slow blink to indicate a malfunction, it may be off to indicate a malfunction, and it may flash quickly to indicate light fixture2is operating on battery power. Different indicator lights or light conditions can be used to indicate which power source is being used to provide power to power supply22. For example, a red indicator light can be used to indicate that the 277 V input power is being used while a green indicator light can be used to indicate that the 600 V input power is being used. Both may be turned on to indicate battery power.

Data relevant to the monitoring of the battery backup system can be delivered to the manager of the facility, to the authority having jurisdiction over the lighting tests, to a remote computer, or to a website through an Ethernet cable, a Power Line Communication protocol, or any of a variety of wireless communications protocols including WIFI or ZigBee. A RuBee (IEEE standard 1902.1) communications protocol may be used for the relatively harsh environments faced by wireless communications systems in underground transportation facilities. In order to communicate the data, each fixture can include a communications device that provides for the desired communications. For example, each fixture2can include a Wifi chip, a ZigBee chip, or a RuBee transceiver. The remote computer can be a computer located in the same facility as the light fixture2providing the reporting or a computer located in a location remote from the facility. The data may be available through the Internet through a web server. The data communicated to the remote location may include information about malfunctions, battery levels, lumen output of LEDs, status of power supply, the identification of which power source is being used, and the physical location of the item having a malfunction so that it can be repaired. A service message can be generated and communicated by text, email, phone, or other communications methods to service personnel.

Each light fixture2also can include a sensor or communications chip that functions as an air sensor that provides data through the above communications protocol. Each light fixture2can include a camera that provides data through the above communications protocol. At the same time, each fixture can include an alarm light or speaker that is triggered by the communications system described above.

Light fixture2described above having the plurality of power inputs can be retrofit into existing light fixtures to provide updated efficient lighting functions. For example, a fluorescent light fixture having one or a plurality of fluorescent bulbs may be retrofit by removing the bulbs and ballast and installing the LEDs and power supply within or associated with the existing fluorescent housing. In these situations, the LEDs can be provided in the form of a flat panel LED that fits within the existing fixture. In one configuration, a fluorescent fixture has a U-shaped bulb disposed at one end of a housing and can accept a power input such as30and34described above. The components of light fixture2may be retrofit into such a housing to provide a LED light fixture that is on during normal use, an emergency light fixture, or a combination of both.

FIGS. 6-14disclose additional embodiments of a light fixture which are indicated generally by the numeral102. This embodiment may be configured to retrofit into the spaces described above or can be configured to have a height of 3.7 inches or less, a width of 6.4 inches or less, and a length of 17.4 inches or less. Fixture102includes at least the fixture housing106and electrical components needed to power LED light sources. Fixture102also may include the components of the mounting arrangement and/or a battery backup system and/or communications devices as described above.

A mounting bracket104shown inFIGS. 12 and 13allows light fixture housing106to be quickly mounted and dismounted for its desired location. The mounting connection can be friction, a snap fit, a connector, or a combination of these. As described above, mounting bracket104is often directly connected to concrete walls with suitable anchors disposed at anchor locations108shown inFIG. 12. Mounting bracket104can be made from stainless steel. Light fixture housing106can be made from steel, stainless steel, galzanized steel, aluminum, polycarbonate, or a different polymer. When made from aluminum, direct contact between stainless steel and aluminum is undesirable especially in hot humid environments because of galvanic corrosion. A spacer (not shown) may be used to prevent direct contact between the two metals while also providing a shock absorber against the repeated vibration forces to which fixture2is subjected. The spacer can be made from an insulating material such as a polymer, a rubber, fiberglass, PVC, or other insulating material.

Light fixture housing106includes spaced upper mounting tabs110and a lower mounting tab112that slide into channels114defined by mounting bracket104. A stop116projects forwardly from the rear wall118of mounting bracket104to stop light fixture housing106from sliding all the way through mounting bracket104. A lock tab120supports a removable second stop122which may be a threaded connector or a rubber knob supported by a threaded connector to lock light fixture housing106in between stop116and second stop122.

Light fixture housing106defines a plurality of ventilation openings130that expose the inside of housing106to the environment surrounding light fixture2. Although ventilation is desirable for the LED light engine132, the water vapor and corrosive elements carried by humid air found in a public transportation facility is not desirable for the power supply134or for the fuses (when such fuses are used). LED light engine132, power supply134and fuses (when used) are carried by housing106and all are removed from mounting bracket104when housing106is removed from mounting bracket104.

The LEDs that produce the light of fixture2are located at the bottom of fixture2and shine down through a protective lens that is designed to direct the light in a desired pattern. Heat sink fins project up from the LED circuits where they are allowed to vent with outside air through openings130. Power supply134can be disposed (1) within a common sealed enclosure140that seals both the power supply134and any fuses from outside air and moisture vapor; (2) power supply134can be disposed within its own enclosure separate and independent from any fuse housing; or (3) power supply134can be disposed within housing106and exposed to the air within housing106.FIG. 9depicts a common enclosure140. This enclosure provides a water-tight and moisture-vapor tight sealed housing for power supply134and a fuse or fuses for fixture102.

Any of the above-described power input configurations and battery backup system configurations can be used with fixture102. Alternatively, power supply134can be connected to a single source of input power30,32, or34or power from batteries20during an emergency. Batteries20and the backup battery system components can be located within housing106or remote from housing106. Different power supplies for different input power sources can be fit within enclosure106. Fixture102thus may be configured for 110V input or 600V input.

The fuses are used to protect power supply134or LED light engine components. When used to protect power supply134, input power is directed to a first fuse prior to being delivered to the power supply134through a positive power connection. The neutral side of the power connection is also fused with a second fuse that is connected to the neutral side of the power supply134with a power connection. As such, each side of the input power source—both positive and neutral—is fused. Providing fuses on the neutral power line protects the user from any back feed through the neutral line. Providing fuses on both sides of the circuit protects the power supply and allows a worker to remove the fuses from both sides of the circuit for safety. This is particularly useful in a three phase 480 Volt system. When fuses are used after power supply134, each side of the direct power loop and can fused (both supply and return lines).

The fuses are carried by fuse holders136that are located in a sealed fuse housing152. Sealed fuse housing152can be a stand-alone enclosure or an extension that is integral with power supply enclosure140. Sealed fuse housing152is carried by housing106and can be disposed within housing106or outside of housing106but connected thereto. Fuse housing152can include a door154that allows the fuses to be accessed, removed, and replaced. Door154includes a gasket or seal that seals the door opening when door154is attached and closed. In the configuration ofFIGS. 8-9, each fuse is held in a fuse holder136that slides out of housing152on a sliding drawer component of housing152to provide access to fuse136. These styles of fuse holders are generally used for the higher voltage applications such as 600 Volt applications. In theFIG. 10-11configuration, fuse holders136are directly accessible through the end of fixture2wherein they can be removed by unscrewing the end of the fuse holder136and removing the fuse from housing152. These styles of fuse holders are generally used for the lower voltage applications. TheFIG. 10-11configuration can use a sealed door154and a sliding drawer as an option. In both of these configurations, both the hot power line and the neutral line or the power supply line and power return line can be fused.

The foregoing description has been made with reference to exemplary embodiments. Modifications and alterations of those embodiments will be apparent to one who reads and understands this general description. The present disclosure should be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or equivalents thereof.