Abstract:
A light source is disclosed. For example, the light source includes an enclosure forming an internal volume, the enclosure having at least one side, a top and a bottom. At least one light emitting diode (LED) may be deployed within the internal volume of the enclosure. Optionally, an optic may be coupled to each one of the at least one LEDs. The light source also includes a potting compound surrounding said at least one LED and substantially filling said internal volume or covering said top of said enclosure and substantially sealing said enclosure.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 60/797,430 filed on May 3, 2006, which is herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a light source, and more particularly to an LED light source. 
     BACKGROUND OF THE INVENTION 
     There are many industrial environments where explosive atmospheres are present due to the nature of the products produced or processed. Facilities such as oil refineries, gas processing plants, grain elevators, etc. are some examples of such environments where electrical discharges must be tightly controlled in order to prevent explosions. 
     Over the years standards have been developed to minimize the potential for electrical discharges such as sparks or arcs in electrical products placed in environments where explosive atmospheres are present. For example Class 1 hazardous environments include those containing flammable gases, vapors or liquids; Class 2 includes combustible dusts; Class 3 includes ignitable fibers. Environments where those explosive atmospheres are sometimes present are further classified as Division 2 environments. Therefore, an environment where flammable gases were sometimes present would be considered a Class 1, Division 2 area. 
     As with any type of environment, lighting is an important element. Lighting fixtures in locations where explosive atmospheres could be present require lighting fixtures which are resistant to exposing electrical discharges. In other words, the lighting fixtures used for Class 1, Division 2 areas should be fabricated such that they are safe for installation in Class 1, Division 2 areas. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the present invention provides a light source. The light source comprises an enclosure forming an internal volume, said enclosure having at least one side, a top and a bottom. At least one light emitting diode (LED) may be deployed within said internal volume of said enclosure. The light source also includes a potting compound surrounding said at least one LED and substantially filling said internal volume. 
     In another embodiment, the present invention provides a light source comprising an enclosure forming an internal volume, said enclosure having at least one side, a top and a bottom. At least one light emitting diode (LED) may be deployed within said internal volume of said enclosure. The light source also includes a potting compound covering said top of said enclosure and substantially sealing said enclosure. 
     In another embodiment, the present invention provides a light source comprising an enclosure forming an internal volume, said enclosure having at least one side, a top and a bottom. At least one light emitting diode (LED) may be deployed within said internal volume of said enclosure. An optic may be coupled to each one of said at least one LED. The light source also includes a potting compound surrounding said at least one LED and substantially filling said internal volume. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The teaching of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: 
         FIG. 1  depicts one embodiment of an embedded LED light source according to the present invention; 
         FIG. 2  depicts a circuit schematic of one embodiment of a power supply according to the present invention; 
         FIG. 3  depicts an alternate embodiment of an embedded LED light source having reflectors according to the present invention; and 
         FIG. 4  depicts an alternate embodiment of an embedded LED light source having lenses according to the present invention. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. 
     DETAILED DESCRIPTION 
     The present invention provides a unique enclosure for a light source, e.g. as used in Class 1, Division 2 areas. In one embodiment of the present invention a light emitting diode (LED) light source is embedded in an optically clear potting compound. By embedding the LED light source in an optically clear potting compound, the LED light source is surrounded and the potting compound completely or substantially fills any voids of an enclosure housing the LED light source. By eliminating all or most of the volume where explosive atmospheres could collect, this approach minimizes the potential that a spark in the LED light source could come in contact with a flammable atmosphere. The optically clear potting compound, while allowing light to leave the device, provides a barrier to vapor, dust and other explosive atmospheres. Since the LEDs and power supply can be potted and sealed, there is no need for heavy metal and glass casings.  FIG. 1  depicts one embodiment of the LED light source  100 . 
     In an exemplary embodiment, the LED light source  100  comprises an enclosure  102 . Enclosure  102  is formed by a top  104 , a bottom  106  and at least one side  108 . The nomenclature of the top  104 , a bottom  106  and at least one side  108  is relative to where LEDs  120  (used hereinafter to interchangeably mean either a single LED or more than one LED) are deployed within enclosure  120 . For example, the portion of the enclosure  102  that the LEDs  120  are mounted on may be referred to as the bottom  106 . In an exemplary embodiment, the bottom  106  may be fabricated from a thermally conductive material to help dissipate heat. 
     Referring back to the enclosure  102 , enclosure  102  typically has as a number of sides  108  in proportion to a perimeter shape of enclosure  102 . For example, if enclosure  102  has a perimeter shape of a square, enclosure  102  would have four sides  108 . However, it is also possible that side  108  is a continuous cylindrical surface. 
     In an exemplary embodiment, the enclosure  102  is fabricated from extruded aluminum with end caps. Consequently, the enclosure  102  can be increased in length by two times or more. This could allow any number of arrays of LEDs  120  and power supplies  124  to provide illumination for very large applications. 
     In an exemplary embodiment, the top  104  is a plate made from an optically clear material, for example glass or plastic. The glass or plastic top  104  provides a surface which is more resistant to some corrosive atmospheres as well as providing a surface which can be more readily cleaned without the danger of scratching or wearing the surface. In addition, using an optically clear top  104  allows the light emitted from LEDs  120  to shine through. Although in the present embodiment, only the top  104  is made with an optically clear material such as glass or plastic, one skilled in the art will recognize, that any one of the sides  108  or bottom  106  may also be made with an optically clear material such as glass or plastic, depending on the desired direction of the light emitted from the LEDs  120 . 
     Enclosure  102  creates a volume  110 . At least one LEDs  120  may be coupled to an LED board  128  and placed within volume  110 . LED board  128  may be fabricated from a thermally conductive material such as for example, a metal core circuit board. Similar to the bottom  106 , as discussed above, fabricating the LED board  128  from a thermally conductive material helps to dissipate heat away from enclosure  102  during operation of LEDs  120 . 
     In an exemplary embodiment, LEDs  120  may be coupled to a LED board  128  that is then coupled to the bottom  106  of enclosure  102 . However, one skilled in the art will recognize that LEDs  120  may be placed anywhere in the volume  110  of enclosure  102 . The number of LEDs  120  could be adjusted based on the desired amount of light required or as required by a particular application. Moreover, multiple rows of LEDs  120  in an array may be placed in the volume  110  of enclosure  102 . Although only four rows of LEDs  120  in array are shown, the invention anticipates one or more rows of LEDs  120 . In addition, different colored LEDs  120  may be used to achieve a desired color output and is not limited to a single colored LED  120 . The enclosure  102  may be fabricated in any shape and size to accommodate the desired number of LEDs  120 . This provides great flexibility to the manufacturing of the present LED light source  100 . 
     The remaining volume  110  of enclosure  102  not filled by the LEDs  120  is substantially filled by a potting compound  122 . The potting compound  122  may be an optically clear potting compound. The potting compound  122  may be made from silicone, acrylic, epoxy or urethane based materials, for example, silicone elastomers or polyurethanes. The potting compound  122  should be optically clear such that sufficient light may be emitted through the potting compound  122  and the top  104 . Two exemplary silicone elastomers known under the trade names of SYLGARD® 182 and SYLGARD® 184, manufactured by DOW CORNING CORP. of Midland, Mich. may be used as the potting compound  122 . 
     Alternatively, for lighting applications that require an air-LED interface, the potting compound  122  may be used over an exterior side of the top  104  of enclosure  102 . This would be useful if a lens  428 , as illustrated in  FIG. 4 , were used in front of the LEDs and an air-LED interface was necessary. The potting compound  122  would still seal the enclosure  102 , but putting the potting compound  122  on an exterior side of the top  104  would allow an air-LED interface. In yet another alternative, the potting compound  122  may be used over an exterior side of the top  104  of enclosure  102  to provide an additional seal in addition to filling the volume  110  of enclosure  102  with the potting compound  122 . 
     The LED light source  100  also comprises at least one power supply  124  coupled to the enclosure  102  to power the LEDs  120 . The power supply  124  may also be sealed using the potting compound  122 . The power supply  124  may also form one of the at least one sides  108 , discussed above, when coupled to enclosure  102 . 
     The power supply  124  used to drive the LEDs  120  is also required to meet certain specifications designed to minimize the potential for electrical discharge. Since the LEDs  120  typically requires a constant current source, the power supply  124  must be able to provide this current while at the same time meeting the electrical requirements for a hazardous location classification (e.g., Class 1 Division 2 power supply).  FIG. 2  depicts a circuit schematic  200  of one embodiment of the power supply  124  which can provide the required constant current for the LED light source  100  used in a hazardous environment. In addition, the power supply  124  also meets the power supply requirements for hazardous environments, such as for example, a Class 1, Division 2 classification. 
     Furthermore, when LED light source  100  uses an embodiment containing multiple rows of LEDs  120  in an array, as discussed above, LED light source  100  may include an equivalent number of power supplies  124  to power each respective row of LED arrays. This provides added redundancy to the LED light source  100 , thereby, increasing the longevity and utilization rate (i.e., minimizing downtime for maintenance or replacement) of the LED light source  100 . 
     The LED light source  100  may also include heat sink fins  126  to help remove heat from LEDs  120  when in operation. The heat sink fins  126  may be fabricated from thermally conductive materials, e.g., aluminum, to help dissipate heat any heat generated from the operation of LEDs  120 . Consequently, heat sink fins  126  help prevent LEDs  120  from failing due to over heating. In addition, heat sink fins  126  may help prevent ignition of any flammable gases, vapors or liquids that may be found in hazardous environments from the heat generated from operating LEDs  120 . The shape, size and number of heat sink fins  126  used may be determined by the number of LEDs  120  used in the LED light source  100 . In an exemplary embodiment, the heat sink fins  126  may be coupled anywhere to the enclosure  102  on an opposing side of the LEDs  120 . For example, the heat sink fins  126  are directly coupled to the same bottom  106  that the LEDs  120  are mounted on. In other words, if LEDs  120  are coupled to an interior side of bottom  106  of enclosure  102 , the heat sink fins  126  would be coupled on an opposing exterior side of the bottom  106 . 
     In alternate embodiments of the present invention, optics may be coupled to one or more of the LEDs  120 . The optics may be used to produce different lighting patterns based on desired lighting requirements. One skilled in art will recognize how to couple the optics to the LEDs  120  based upon the type of optic being used and the type of LED  120  being used. 
     For example, as illustrated in  FIG. 3 , the optics may be reflectors  328 .  FIG. 3  illustrates an exemplary LED light source  300  using reflectors  328 . The shape and size of the reflectors  328  may be varied to produce light in different patterns based on the desired lighting requirements. The number of reflectors  328  used may also vary based on the desired lighting requirements. The reflectors  328  may be fabricated from molded plastic or polished metal. If molded plastic is used to manufacture the reflectors, the molded plastic may be metalized with a reflective material, such as for example, aluminum. The LED light source  300  may be similar to LED light source  100  in all other respects as illustrated by  FIG. 3 . 
     In yet another embodiment, the optics may be lenses  428 .  FIG. 4  illustrates an exemplary LED light source  400  using lenses  428 . Similar to reflectors  328 , various shapes of lenses  428  may be used to produce light in different patterns based on the desired lighting requirements. The number of lenses  428  used may also vary based on the desired lighting requirements. The lenses  428  may be fabricated from glass or plastic. 
     When using lenses  428 , the LEDs  120  may require an air-LED interface as discussed above. Therefore, the LED light source  400  using lenses  428  may use the potting compound  122  over an exterior side of the top  104  of enclosure  102 . The potting compound  122  would still seal the enclosure  102 , while allowing an air-LED interface. Consequently, the potting compound  122  would prevent any flammable gases, vapors or liquids that may be found in hazardous environments from entering the enclosure  102  and being ignited by any sparks or arcs that may be created by the operation of LEDs  120 . 
     The embodiments of LED light sources  100 ,  300  and  400  disclosed above, allows for a lighter unit since the heavy metal barrier and thick glass cover of traditional hazardous location lights are eliminated. Using this approach also allows greater flexibility in lighting fixture design. The use of LEDs  120  in the unit provides advantages including: relatively small size of source; long lifetime and low operating voltage. Although the LED light sources  100 ,  300  and  400  are discussed as being mounted in facilities where hazardous environments may be present, one skilled in the art will recognize that LED light sources  100 ,  300  and  400  may have application in other environments. 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.