Abstract:
Display case lighting comprising a lens with integrally formed features on its interior to mechanically retain LED units therein, at least one LED unit comprising a base and diodes mechanically engaged with the integrally formed features of the lens, an electrical connector to connect the LED units to a power source, and at least one end cap, which preferably incorporates the electrical connector. Sealing implements including a boot seal to seal the electrical connection and a plug cover to cover any unused electrical connectors may be provided, as well as an adhesive to secure the end cover to the lens and seal the connection therebetween, rendering the lighting assembly suitable for use in wet or potentially explosive environments. The externally accessible components may also comprise materials approved for contact with food items.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     FIELD OF THE INVENTION 
     The invention is in the field of a lighting, particularly, lighting elements suitable for use in display cases. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention comprises a lighting assembly having an elongated lens comprising a tube with preferably at least one open end and having integrally formed retaining features on the interior of the tube, where at least a portion of the lens is transparent to visible light, an LED lighting unit comprising a base and light emitting diodes which is mechanically engaged with the retaining features on the interior of the tube, an electrical connector which is electrically connected to the LED lighting unit, and which is capable of receiving electrical power from an electrical power source and transmitting such incoming electrical power to the LED lighting unit, and preferably an end cap which is mechanically engaged with the at least one open end of the lens. 
     The lighting assembly preferably comprises externally accessible components manufactured using materials approved by relevant regulators for contact with food items and which are readily able to be cleaned. The lighting assembly is also preferably manufactured as a sealed unit, such that it can be installed and used in potentially explosive or wet environments. Further the lighting assembly is preferably manufactured having an integrated light shield as part of the lens, and so that a single lens can be efficiently used with single and dual LED configurations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view showing the position of the lighting assembly in a display case, with the lighting assembly shown in dotted lines; 
         FIG. 2  is a top view showing the position of the lighting assembly in a display case, with the lighting assembly shown in dotted lines; 
         FIG. 3  is a front view of the display case lighting assembly; 
         FIG. 4  is a side view of the display case lighting assembly; 
         FIG. 5  is an end view of the display case lighting assembly on the end that is to be wired; 
         FIG. 6  is an end view of the display case lighting assembly on the end that will not be connected to a power source, with the boot in place; 
         FIG. 7  is a rear view of the display case lighting assembly; 
         FIG. 8  is a cross sectional view of the display case lighting assembly, taken along line  8 - 8  of  FIG. 3 ; 
         FIG. 9  is a cross sectional view of the display case lighting assembly taken along line  8 - 8  of  FIG. 3 , with one of the LED lighting elements removed; 
         FIG. 10  is a top perspective view of the end cap used on the display case lighting assembly; 
         FIG. 11  is a cross sectional view of the boot seal used in the barrel fitting on the end cap; 
         FIG. 12  is a cross sectional view of the plug cover used in the barrel fitting on the end cap; and 
         FIG. 13  is a cross sectional view of the display case lighting assembly, taken along line  8 - 8  of  FIG. 3 , showing the use of coextruded lens materials; 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The lighting assembly  20  described herein is an elongated LED lighting assembly  20  which can be used in place of fluorescent or other lighting apparatus in locations where even, efficient lighting is desired, and preferably in locations which may come into contact with food or that may require cleaning or involve liquids or that are potentially explosive. Lighting assembly  20  is particularly suitable for use in locations such as display cases  22 , having clear doors  24  and shelves  26  to hold product  28 , where lighting on the front of products  28  is desired. ( FIGS. 1-2 ) Particularly, lighting assemblies  20  are suitable for use in refrigerated or frozen display cases  22 , such as the type used to display chilled food and beverages, where the use of fluorescent lighting can be energy-intensive and inefficient, not to mention costly and potentially toxic if a fluorescent light is broken. 
     One preferred embodiment of lighting assembly  20  includes two elongated LED units  30  affixed inside a lens  36 , having two end caps  58 ,  60  fitted on the ends of lens  36  and electrically connected to LED units  30 , wherein end caps  58 ,  60  further include electrical connectors  64  to connect lighting assembly  20  to an incoming power supply. ( FIGS. 3-7 ) 
     Each LED unit  30  comprises an elongated generally rectangular base  32 , with light emitting diodes  34  spaced along the length of base  32 . LED units  30  as described herein preferably include a plurality of small diodes  34  along the length of base  32 , to limit the power consumption and heat generation of individual diodes  34  and to disburse the light and generated heat along the length of base  32  and lighting assembly  20 . LED units  30  may include a printed circuit board, wherein diodes  34  are printed onto base  32  for low profile design and a small, efficient size. Such bases  32  and printed diodes  34  may be manufactured in various lengths and widths, to accommodate the desired height and size of lighting assembly  20 . 
     Lens  36  comprises a hollow column of material, generally in the shape of a “D,” with flat side  38  to facilitate mounting, and curved side  40  through which light L is transmitted. ( FIGS. 8 ,  9 ) Lens  36  further comprises guides to mount LED units  30  on its interior. Two single mounts  42 ,  44  extend from flat side  38  toward the apex of curved side  40 , with each single mount  42 ,  44  comprising two ridges  46  extending the length of lens  36  and defining a channel  48 ,  50  therebetween. A double mount  52  extends from the apex of curved side  40  toward flat side  38 , wherein one half of double mount  52  comprises two ridges  46  defining a channel  54  and the other half of double mount  52  comprises two ridges  46  defining a channel  56 . Channels  48 ,  54  are sized and positioned relative to each other adequately to receive one LED unit  30 , and channels  50 ,  56  are sized and positioned to receive to one another adequately to receive another LED unit  30 , with each LED unit  30  having one side edge thereof retained in single mount  42 ,  44  and the opposite side edge thereof retained in one half of double mount  52 . LED units  30  are installed in lens  36  with diodes  34  facing outward. 
     Two end caps  58 ,  60  are placed over the end of lens  36 , in electrical connection with LED units  30  and are sealed thereto with some type of adhesive, glue, or other sealing agent, which is preferably water resistant and UV-stable. Each end cap  58 ,  60  fits over one end of lens  36 , with a shape and features to interact with the outer circumference of lens  36  and provide a sealed connection therewith, and further comprises a mounting plate  62  and an electrical connector  64 . ( FIG. 10 ) End caps  58 ,  60  are preferably identical so that lighting assembly  20  can be mounted with either end at the top and either end at the bottom. 
     Mounting plate  62  has at least one hole  66 , which permits lighting assembly to be mounted on a flat surface, such as the space between display cases  22 , by fastening a screw  68  or other device through hole  66  in mounting plate  62 . Electrical connector  64  is preferably a barrel connection jack, which is adapted to receive power from an incoming power source and is electrically connected to LED unit  30 , such that electrical connector  64  is capable of supplying DC electrical power to LED unit  30 , preferably supplying 12-24 Volts DC power to LED unit  30 . 
     To seal the connection between end cap  58  with electrical connector  64  and the incoming power source, a boot seal  70 , comprising a generally cylindrical piece of non-conductive material, is placed over the connection. ( FIG. 11 ) Additionally, due to the preferred identical construction of the end caps  58 ,  60 , electrical connector  64  on the second end cap  60 , which is not being used to supply power to LED unit  30 , may be covered with a small, non-conductive plug cover  72 , which operates as a removable seal to protect the exposed electrical connection. ( FIG. 12 ) Also due to the identical construction of end caps  58 ,  60 , the incoming power source may come from either the top or the bottom, or lighting assembly  20  can be reversed from its original orientation upon simply switching boot seal  70  and plug cover  72 . 
     With regard to construction and manufacturing of lighting assembly  20 , as described above, LED units  30  may be manufactured using known methods, to produce elongated LED units  30  of the desired length to illuminate the desired space. Further, multiple LED units  30  can be electrically connected and installed along the length of a single lens  36 . LED units  36  may also be manufactured to provide light of various qualities and colors of LED lighting. 
     When lighting assembly  22  is intended for use in display cases  22  containing food products  28 , the components of lighting assembly  20  which may come into contact with products  28  are preferably safe for food contact, to reduce the risk of food contamination and so that further shielding of lighting assembly  20  is not necessary. These components include lens  36 , end caps  58 ,  60 , boot seal  70  and plug cover  72 . 
     Lens  36  is preferably manufactured using shatter-proof or shatter resistant material which is transparent to the light being generated by LED units  30  and which provides durable protection for LED units  30 . One example of such a material is Eastman Tritan Copolyester TX2001, sold by the Eastman Chemical Company, which is formulated to allow for extrusion into a durable product with a high degree of clarity, and which can be used repeatedly for food contact articles. The extruded material may also be provided with a thickness which provides extra protection to the LED units  30  within lens  36 , such as a thickness of 2.5 mils, which provides additional durability as compared to traditional fluorescent lighting. 
     A preferred method of manufacturing lens  36  is extrusion, or if multiple materials are used, coextrusion, of a polymeric material into a tube of the desired cross sectional shape. Lens  36  can be cut to a desired length, with some preferred lengths for use in refrigerated case being from about 12 inches to about 60 inches. Lens  36  may be manufactured using one material which is transparent to visible light, or may contain two or more materials, with the two or more materials having varying transparency to visible light. For example lens  36  may comprise a generally transparent material  74  and a more opaque material  76 , with the more opaque material  76  making up flat side  38  of lens  36 , and optionally some portion of the adjacent curved side  40  so as to operate as a light shield and narrow the field of light L emitted from lighting assembly  20 . ( FIG. 13 ) If a more opaque material  76  is used for a portion of lens  36 , additional pigment can be added to the first material  74  to make opaque material  76 , or a separate compatible opaque material  76  may be used. 
     Extrusion of lens  36  allows for the ready shaping of the cross section of lens  36 , and readily permits formation of channels  48 ,  50 ,  54 ,  56  which extend along the entire length of lens  36  to secure LED units  30 . However, other methods of production of lens  36 , such as molding, would permit the use of alternate integrally formed structures to secure LED unit  30 , such as intermittent notches or fingers to guide LED unit  30  and secure it into position within lens  36 . 
     End caps  58 ,  60  are preferably manufactured using a durable, flexible material which is able to be sealed against lens  36  and adhered thereto using a compatible adhesive, and which retains the flexibility and sealing ability even in cold environments where lighting assembly  20  may be used. One example of such a material is a thermoplastic vulcanizate Santoprene TPV 241-80, manufactured by Exxon Mobile, which is a flexible, low compression set material which is available in an NSF grade to permit contact with food items. End caps  58 ,  60  are preferably hermetically sealed to lens  36 , which permits lighting assembly  20  to be used in explosion proof environments and wet environments, preferably with an International Protection Rating of IP67 (dust tight and able to be immersed in up to 1 meter of water). 
     Boot seal  70  and plug cover  72  are preferably manufactured using a material which will conform to end caps  58 ,  60 , and which is also available with NSF food grade certification, such as a silicone material. 
     Lighting assembly  20  can be attached to the mounting surface in a number of different ways, and does not necessarily require mounting holes  66  in end caps  58 ,  60 . Additional methods of affixing lighting assembly  20  to a mounting surface include, but are not limited to, nails, brackets, adhesives, glues, loops or other fasteners which hold lighting assembly  20  in place using friction, hook and loop fasteners, or any other method for securing, preferably in a removable fashion, lighting assembly  20  to the mounting surface. Methods of mounting lighting assembly  20  may also depend upon the desired permanence of the mount, whether it is being used to retrofit a previously used lighting connection, and whether it is intended to be readily re-configured by end users. 
     When a lighting assembly  20  is intended to illuminate adjacent display cases  22 , to maximize efficiency LED units  30  are arranged at an angle of approximately 60 degrees to each other, with single mounts  42 ,  44  and double mount  52  of lens  36  positioned to hold LED units  30  in this position. Since LED diodes  34  on LED unit  30  generally have a field of illumination L which extends outward at an angle of approximately 120 degrees from the face of diode  34 , the angle of the LED unit  30 , combined with the field of illumination L, results in light coverage which extends outward from lighting assembly  20  at an angle of greater than 180 degrees in each direction, to illuminate each adjacent display case  22 . ( FIG. 2 ) This field of illumination L results in light which illuminates the front of products  28  in display case  22 , while projecting only a small amount of light out into the aisle. The angle of LED units  30  can be modified, to cast light with the desired field of coverage, and LED units  30  can be placed asymmetrically to cast light in the desired field of illumination. 
     Additionally, when a more opaque material  76  is used as a portion of lens  36  to create a light shield which includes the flat side  38  of lens  36  and a portion of each curved side  40 , the field of illumination L may be reduced, such that the light extends outward at a 180 degree angle or less, as desired, as illustrated by L′. Depending upon the end use of lighting assembly  20 , a smaller field of illumination L may be desired, e.g., to reduce the amount of glare that would reach the eyes of a consumer outside of display case  22 . 
     When used for a refrigerated case, each LED unit  30  within lighting assembly  20  preferably illuminates an area which is about 4-6 inches deep (the front of shelves  26  with products  28 ), and which is approximately 20 inches wide. Since there are preferably two lighting assemblies  20  to illuminate each display case  22 , one from each side, the total width of the case may be greater than 20 inches. Certain commonly used widths for refrigerated display cases  22  are between about 24 inches and about 29 inches. Because of the bell curve distribution of LED lighting, the use of two LED units  30  projecting from different sides of display case  22  results in an even light over the front of display case  22 . 
     The use of LED units  30  mounted at approximately 60 degrees, as described above, provides an additional benefit, in that a triangular air-filled space is formed between the back sides of LED units  30 , wherein the space functions as a heat sink, such that a separate heat sink is not necessary to cool lighting assembly  20 . The lower generation of heat by LED units  30 , combined with the space is generally sufficient to maintain proper operating parameters for lighting assembly  20 . 
     Another preferred embodiment of lighting assembly  20 ′ for use in a vertical orientation at the end of a series of display cases  22 , includes one elongated LED unit  30  placed within lens  36 , with LED unit  30  directed toward the adjacent shelves  26  in display case  22 , with two end caps  58 ,  60 , one at each end of lens  36 . ( FIGS. 1-2 ) This configuration, which is identical to the previously described preferred embodiment except that only one LED unit  30  is placed inside lens  36 , can be used on either end of a series of display cases  22 , projecting light L to either side, by flipping lighting assembly  20 ′ top to bottom. Lighting assembly  20 ′ may also be placed horizontally at the top or bottom of display case. Due to the identical construction of lens  36  for use on the end of a series of display cases  22 , and the identical construction of end caps  58 ,  60 , a single type of LED unit  30 , lens  36  and end cap  58 ,  60  can be used for all lighting assemblies  20 , regardless of intended location, reducing inventory requirements and manufacturing tooling costs. 
     Lighting assembly  20  described herein is also suitable for use in other applications, where even, energy efficient lighting is desired. Due to the sealed nature of lighting assembly  20 , and lower heat generation of LED lighting as opposed to traditional fluorescent lighting, lighting assembly  20  may also be suitable for use in other locations where traditional fluorescent lighting poses certain risks. For example, in potentially explosive environments, or environments subject to repeated cleaning with potentially harsh or corrosive cleaning agents. 
     LED lights also use less energy than traditional fluorescent lights, provide a faster start-up time in cold environments, and provide a pleasing light which can be customized to certain color temperatures, such as an LED color temperature of from about 3,800 degrees Kelvin to about 4,400 degrees Kelvin, which is a desirable color range for the illumination of grocery items in a refrigerated case  22 . LED light L is emitted from diodes  34  in a bell curve, such that the intersecting light from an LED unit  30  on the right and an LED unit  30  on the left create an even light across the front of display case  22 . 
     Of course it is understood that the above is a description of preferred embodiments, and that various changes and alterations can be made to the lighting assembly without departing from the spirit and broader aspects of the invention.