Patent Publication Number: US-8115393-B2

Title: LED tubular lighting fixture

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates, in general, to LED lighting, and, in particular to a lighting system that includes tubular LED lighting fixtures that may be used for lighting in a variety of applications. 
     2. Description of the Prior Art 
     The prior art is replete with LED lighting fixtures and assemblies. Examples of same may be found in: Solow, U.S. Pat. No. 4,761,720; Sears, et al., U.S. Pat. No. 5,222,799; Hunter, U.S. Pat. No. 6,283,612; Archer, et al. US2002/0149933; Hefright, et al., 2006/0202850; Tatar, US2003/0038727; Thomas, et al., U.S. Pat. No. 7,165,863; Beauchamp, US2007/0064428; Friedrich, et al., US2007/0291503; Wang, US2008/0089064; and, Huang, et al., U.S. Pat. No. 7,441,922. 
     The prior art fails to provide a truly usable LED fixture and assembly that will permit one to incorporate same in existing conduit based wiring, to become both general as well as emergency lighting, and allow for the electrical supply to come from a variety of alternate sources. 
     SUMMARY 
     A primary object of the present invention is the provision of a tubular LED lighting fixture that is applicable for use in multiple applications. 
     These and other objects, features and advantages are accomplished in accordance with the teachings of the present invention, one illustrative embodiment of which comprises: a tubular LED lighting fixture comprising: a heat sink shell; a printed circuit board supported on the shell and having an upper surface and a bottom surface, longitudinally extending laterally spaced wiring on the upper and bottom surfaces, and, transverse heat pipes running through the printed circuit board; a plurality of LEDs connected in series across the laterally spaced upper surface wiring and spacedly mounted along the printed circuit board; a high frequency electronic driver mounted in the shell and connected in series with the LEDs; voltage limiting devices mounted across the laterally spaced bottom surface wiring of the printed circuit board and in parallel with the LEDs; an on-off switch for the fixture; a lens bonded to the shell, covering the printed circuit board for directing and delivering light from the LEDs, the shell and lens forming a tube for enclosing the LED bearing printed circuit board; the tube so formed having sealed ends to form a watertight fixture; and, input wires extending from the high frequency electronic driver through at least one of the tube sealed ends. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Other objects, features and advantages of the present invention will be apparent from the following detailed description and accompany drawing, wherein: 
         FIG. 1  is an exploded, perspective view of a portion of the tubular LED lighting fixture of the present invention; 
         FIG. 1A  is a side sectional view of a portion of the tubular LED lighting fixture wired to a connector; 
         FIG. 2  is a diagrammatic, top view of the printed circuit board of the LED lighting fixture; 
         FIG. 3  is a diagrammatic, bottom view of the printed circuit board of the LED lighting fixture; 
         FIG. 4  is an enlarged, diagrammatic sectional view showing the fixture&#39;s driver circuit and wiring; 
         FIG. 5  is a perspective view of a completed LED tubular lighting fixture wired to connectors; 
         FIG. 6  is a diagrammatic view of a portion of a lighting system for a building where LED lighting fixtures are sealed between conduits; 
         FIG. 7  is a perspective view of a portion of a tubular LED lighting fixture adapted for wiring to a connector; 
         FIG. 8  is a circuit diagram for the power to energize all of the LED devices in an array of devices; 
         FIG. 9  is a circuit diagram for the power to energize selected ones of a plurality of LED tubular lighting fixtures; 
         FIG. 10  is a schematic circuit diagram of an LED lighting system, utilizing various power inputs and controls; 
         FIG. 11  is a perspective, exploded view, illustrating a stand-alone tubular LED lighting fixture inserted and held within a connector; and, 
         FIG. 12  is a schematic circuit diagram allowing 24 or 48 application. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1  of the drawing an LED (light emitting diode) lighting fixture  10  is seen as comprising: a shell or extrusion  11 ; a heat dispersing printed circuit board  12  supported on the shell  11  and having an upper  13  ( FIGS. 1 &amp; 2 ) and bottom surface  14  ( FIGS. 1A &amp; 3 ), longitudinally extending, interconnected, laterally spaced wiring  15  and  16  on the upper  13  and bottom  14  surfaces and transverse heat pipes  17  running through the printed circuit board  12 ; a plurality of LEDs  18  connected in series across the laterally spaced upper surface wiring  15  and spacedly mounted on the printed circuit board  12 ; a high frequency electronic driver  19  ( FIGS. 1A &amp; 4 ) embedded within an insulating jacket  20  and mounted in the shell  11 , with input wires  21  leading into the driver  19  from an external DC power source and feed wiring  22  leading from the driver  19  to the upper wiring  15  for the LEDs  18 , the driver  19  being connected in series with the LEDs  18 ; voltage limiting devices  25  mounted across the laterally spaced bottom surface wiring  16  and in parallel with the LEDs  18 ; a lens  31  bonded to the shell  11  and covering the printed circuit board  12  for directing and delivering light from the LEDs  18 , the shell  11  and lens  31  forming a tube  32  for enclosing the LED bearing printed circuit board  12 ; the tube  32  so formed having sealed ends  33  ( FIGS. 1A and 5 ) to form a watertight, LED tubular lighting fixture  10 . 
     The input wires  21  and other wiring extend through at least one sealed end  33  of the tube  32  to a connector  34 . Connector  34  ( FIG. 1A ) is ultimately wired to a dc power supply. 
     The shell or extrusion  11 , typically aluminum, provides structural support for the printed circuit board  12  and also acts as a heat sink for the heat generated on the printed circuit board  12 . It provides extremely high thermal dissipation for the LEDs  18  and gives extremely low junction temperature and extended service life. Board  12  slides in from one end of the extrusion  11  and in this way, when and if necessary, boards may be replaced within the tube  32 . 
     The rigid printed circuit board  12 , typically made from regular fiberglass material products, is very resilient to shock and is held rigid by the extrusion  11 . 
     Its heat pipes  17  that go through the board  12 , normally less than a millimeter in diameter, allow localized heat build-up around the LED chips  18  to circulate around the circuit board  12  and thus cool down the entire LED chip array. The wiring  15 ,  16  on the upper  13  and bottom  14  surfaces of the board  12 , which are interconnected, is typically copper. 
     The LEDs  18  are readily available surface mount devices, typically 3 millimeters square, die type F12310SA-BL(A) that are soldered to the upper wiring or bus  13  on the printed circuit board  12 . Surface mount LEDs  18  have a reduced heat load and distribute the light across the whole surface of the printed circuit board  12  and thereby contribute to linearity. The type of chip selected helps to distribute the light evenly across the whole length of the tube to be formed. This, in turn, leads to a uniform light path on a surface to be illuminated, e.g., wall, ceiling or floor. 
     The high frequency electronic driver  19  controls the drive current to the LEDs  18  from their DC supply and ensures that the LEDs  18  reach their maximum life and maintain steady light output. It has the side benefit of allowing the bus to operate at above the rated output thus ensuring less voltage drop down the cable. 
     The voltage limiting devices  25 , e.g., Zener diodes, mounted on the bottom surface  14  of the printed circuit board  12  and in parallel with the LEDs  18  serve to precisely regulate voltage across the LED die. 
     Tube  32  may include an on-off switch  26  that would be wired into the positive lead to the driver  19  and mounted in the extrusion  11  to allow individual switching on and off of a tube. 
     The transparent lens  31  is to distribute light evenly across a field, is typically ⅛″ thick, ribbed on the interior with curvature of 120 degrees and made of impact resistant polycarbonate material. The lens  31  is joined to the extrusion  11  with a sealant, typically silicone. It seals and protects the LEDs  18 , making them dirt, water and vandal proof 
     The lens  31  may also be made opaque like, for example, a fluorescent tube, by doping the polycarbonate material with a bit of titanium oxide to make it white, in which case the lens  31  functions also as a diffuser. 
     The extrusion  11  and lens  31 , together form a tube  32 , the ends of which are sealed with an adhesive lined heat-shrink tubing  33  ( FIGS. 1A and 5 ). A connector  34  at one end of the tube  32  is joined to the wiring  21  leading to the driver  19 . A cable  35  at the opposite end of the tube that is electrically connected to the circuitry at the end of the printed circuit board  12  within tube  32  leads to another connector  34  that, in turn may lead to another tube  32 . Alternatively, the circuitry may be terminated within the tube  32  where only one tube  32  is to be powered. More than one board can be wired within a single tube and be separately energized, if desired, such as in a bi-level mode. 
     Referring to  FIG. 6 , a portion of an LED system is shown for a building or structure. It may be formed by sealing an LED tubular fixture  60  into conduits  61  for example, ¾ inch schedule 40 plastic conduit, with couplers  62  at the juncture location between tube  60  and conduit  61 . 
     The tube  60  and conduit  61  are essentially the same diameter. Only one tube  60  is shown, but any number of fixtures can be included in the system. Cabling to the fixtures runs through the conduit to a power source. Since the fixture is powered by a low voltage DC source, the danger of running high voltage current through narrow plastic conduit is eliminated. Additionally, with this system, existing track light systems can be replaced with greatly reduced energy and maintenance costs. The system can be operated over existing wiring, where desired, so wholesale rewiring is not required. 
       FIG. 7  is an exploded cutaway view illustrating the interconnection of the wiring  63  of an LED tubular fixture  60  to cabling  64  through conduit  61  via connector  65 . 
     The circuit arrangement shown by the diagram in  FIG. 8  is for energizing all of the LED devices in an array of devices, with one of the lead lines L 1 , being connected to all the LED fixtures, not just to a single or selected LED fixture as in  FIG. 9 , that follows. 
       FIG. 9  is a circuit diagram for the power to energize selected ones of a plurality of LED tubular lighting fixtures. In a typical embodiment, AC power is fed to an industry standard AC-DC converter  71  that acts as the power source to the fixture. Typically, the fixture is powered by a 24 volt DC operating voltage. The typical ac line voltage of 115 is transformed to the DC voltage. The output from converter  71  is fed to battery charger  72 , thence through a relay  73  to an LED fixture via lead lines L 1 , L 2 . A trickling charge is provided from charger  72  to a battery back-up  74 . In normal operation, the LED fixture is powered from converter  71 . In the event that power from converter  71  is removed intentionally or due to a power failure, relay  73  is activated to direct power to the LED fixture from battery back-up  74 . This particular arrangement is utilized for a single LED fixture or a selected one of a plurality of LED fixtures. 
       FIG. 10  is a schematic circuit diagram of an LED lighting system, utilizing various power inputs and controls. 110V AC power is fed to a unit  81  that includes an AC-DC converter that acts as a power source. The converter may also be powered by other AC/DC renewables such as wind, solar or hydropower. Unit  81  also includes a timer unit that is timed to access the power grid at those times when utilities charge for power at a lower kilowatt rate such as in the early morning hours. The output from unit  81  is fed to a battery charger/controller  82 . A trickling charge is provided from battery charger/controller  82  to a local battery bank  83 . Output from unit  81  could be operated with a bus voltage at 28 volts to allow for charging the back-up battery system  83 . The local battery bank  83  may also be powered from a large, remote battery storage source  84  or other remote DC renewable sources such as photovoltaics. 
     In normal operation a central sensor switching unit  85  is powered from unit  81  through battery controller  82  and thence onto a plurality of series connected LED fixtures  80  via leads L 3 . 
     Unit  85  includes an on-off switch and may also include a plurality of control modules to effect, motion sensing, daylight sensing, PIR, dimming, bi-level control, etc. The controls could be extended to currently available detectors, e.g., smoke, CO, etc. that would provide a failsafe emergency illumination system as part of the general illumination structure of an entire building at little or no additional cost. In the event power is removed from unit  81 , either intentionally or due to a power failure, power will be furnished either to the entire system of fixtures  80  from local battery source  83  via leads L 3  or to a limited back-up set of fixtures  80  via leads L 4 . The limited back-up set of fixtures may also have a local set of sensors. These fixtures can be positioned anywhere within the system utilizing the same conduit.  FIG. 11  illustrates a stand-alone tubular LED lighting fixture  91  inserted and held within a connector  92  such as a Speakeron NL4, produced by Neutrik or a Cliffcon 4PC made by CliffUK. 
     In the circuit arrangement of  FIG. 12 , with two 24 volt LED tubes  60  together in a series configuration, 48 volt operation is possible, allowing for widespread deployment of the system in existing or new battery back-up installations. Because this system with its LED lighting offers such a low load, it will be possible to remove much of the household and commercial lighting load from the national power grid. This low load, for instance, would reduce the size of a photovoltaic or wind turbine power source to an economically viable size due to the up to 80% reduction in load over conventional light sources. Therefore, permanent battery backup of such a system is feasible (i.e. charge by day, discharge by night). 
     The tubular lighting fixture could be plugged into a water tight connector connected to small storage batteries and energized by a solar panel, thus providing low cost lighting that could be deployed anywhere in the world such as in mobile applications. The plug-in tubular lighting fixture could also be used for replacement of track lighting, in retail shops, art museums, etc. 
     The advantages of the LED tubular lighting fixture and its incorporation onto various systems are many fold. Operation is with low voltage DC power and can, in many cases, use existing wiring. The fixture provides efficient illumination and reduces power consumption and space requirements. It is cool in operation, with reduced heat generation. The fixture is very rugged and operable over a wide range of temperatures The fixture is designed to operate between −40 and +50 degrees Centigrade and in areas of high humidity and/or abrasive particulates. 
     It should be obvious that changes, additions and omissions may be made in the details and arrangement of parts without departing from the spirit and scope of the invention as hereinafter claimed.