Abstract:
A display case is provided having vertical members with internal conductors. The conductors are coupled to a source of low voltage electrical power such that adjacent vertical members are of differing electrical polarity. Shelf supports are designed to make electrical contact with the internal conductors when engaged in a vertical member. A light fixture, disposed on the underside of a shelf is electrically coupled to the shelf supports thereby completing an electrical circuit for energizing the light fixture.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to methods and apparatus for the display of items in a residential, office, commercial, or retail environment, and more particularly to a display system including shelves having a low voltage light fixture mounted underneath. 
     In a retail environment it is common for merchandise to be displayed on a system of adjustable shelves. For example a display case may resemble a bookcase. This type of display case typically has a number of holes bored into opposing sides of the case. Pegs inserted into the holes support shelves for displaying items, such as merchandise or objet d&#39;art. Such displays may be easily rearranged by relocating the pegs to different sets of holes in the sides of the display case. 
     Alternatively, the system of adjustable shelves may comprise a wall display. Typically, a number of vertically-oriented, slotted standards are attached to a wall. Brackets having hooks designed to engage the slots on the standards support the shelves. Such displays may be easily rearranged by relocating the brackets to different slots in the vertically oriented standards. 
     To attract customers it is important that a merchandise display be aesthetically pleasing so as to present the merchandise to a potential customer in a highly visible and attractive manner. In many retail establishments, the major source of lighting is wide area illumination provided by ceiling mounted light fixtures, supplemented with spot lighting to accent and highlight specific areas or merchandise. When non-illuminated shelving is used, shelves nearer the ceiling cast shadows onto lower shelves which results in less than optimal lighting of merchandise displayed on the lower shelves. It is therefore desirable to provide a means of illuminating merchandise on lower shelving or racks of a display. 
     Prior art attempts to provide illuminated display systems have been less than satisfactory either because they are aesthetically displeasing or are cumbersome and inflexible. Early attempts at providing illuminated shelving were essentially ordinary light fixtures mounted to the underside of a display shelf. A conventional power cord was then run from the light fixture to an outlet. Preferably, the cord was strung under shelving, behind merchandise on display, or otherwise hidden from a customer&#39;s view so that it would not detract from an otherwise pleasing display. For a system of fixed shelving, or shelving with a limited range of adjustment, the power cord may be hidden from view fairly successfully. However, when using vertically adjustable shelving, the power cord would typically droop or otherwise be exposed to view. 
     Previous systems have attempted to alleviate some of these difficulties by providing an outlet or power source that may be moved within a limited range so that it is located adjacent to a shelf containing a light fixture. For example, U.S. Pat. No. 5,022,720 discloses a bakery display case that provides vertically adjustable shelves having a light fixture mounted on the front. A plurality of electrical outlets are slidably mounted in a channel at the rear of the display area. The outlets may be relocated vertically within a limited range so that an outlet is juxtaposed adjacent to each shelf, to help minimize power cord exposure. 
     Alternatively, U.S. Pat. Nos. 4,973,796 and 5,425,648, disclose vertical shelf standards including internal conductors. The conductors are housed within the standards in such a way that an ordinary shelf bracket would not contact the conductors. Specially designed couplers include spring wires or clips that contact the internal conductors when the coupler is inserted into the shelf standard. In a display unit according to either of these patents, an illuminated shelf may be inserted into and supported by a pair of shelf standards and a special electrical coupler cabled to a light fixture may be inserted into one of the shelf standards just below the shelf itself to help minimize cable exposure. 
     While the aforementioned patents solve the problem of providing power to shelf light fixtures, they involve the use of shelf standards and connectors that are electrically and mechanically complex and are therefore more costly to manufacture than conventional shelf standards, and are more susceptible to failure due to mechanical fatigue and wear. Furthermore, electrical connections to the internal conductors of the shelf standards are made by a separate, specially designed connector located adjacent to, but not integral with, a supporting bracket for an illuminated shelf, so the power cord is not entirely hidden from view. 
     In view of the foregoing, it would be desirable to provide a system of illuminated shelving wherein electrical connections for energizing the illuminated shelves do not detract from the aesthetic appeal of the system. 
     It would also be desirable to provide a system of illuminated shelving wherein the components thereof are electrically and mechanically simple in design and therefore relatively inexpensive to manufacture. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide a system of illuminated shelving wherein electrical connections for energizing the illuminated shelves do not detract from the aesthetic appeal of the system. 
     It is also an object of the invention to provide a system of illuminated shelving wherein the components thereof are electrically and mechanically simple in design and therefore relatively inexpensive to manufacture. 
     These and other objects and advantages of the present invention are realized by providing a modular, low-voltage, low-profile light fixture mounted to a bottom surface of a shelf. The light fixture includes an extruded base having a light track, or channel, for accepting track light style lamp holders. The base may be cut to length to fit the shelving in a display system. End caps, adapted to couple a conductive shelf support to buses in the channel, are attached to each end of the base. If desired, an extruded lens may be attached to the base and cover the lamp holders. The shelf supports, which may include pins or brackets and the like, are inserted and receive power from conductors in the side of a display case or internal to the vertically-oriented standards. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
     FIG. 1 is an exploded perspective view of an illustrative display case constructed in accordance with the principles of the present invention; 
     FIG. 2 is an exploded perspective providing a more detailed view of an illustrative embodiment of the lighted shelf of FIG. 1; 
     FIG. 3 is a cross sectional view of a base and lens of the light fixture of FIG. 2; 
     FIGS. 4A and 4B are respectively, front and rear perspective views of an assembled end cap of FIG. 2; 
     FIG. 5 is a detailed exploded view, in perspective, of an end cap of the light fixture of FIG. 4A and 4B; 
     FIGS. 6A and 6B are, respectively, a cross section and elevation of the electrified support of the display case of FIG. 1; 
     FIGS. 7A and 7B are, respectively, front and rear perspective views of an exemplary coupling block for use with the electrified support of FIGS. 6A and 6B; 
     FIG. 8 is an alternative embodiment of an illustrative display system in accordance with the principles of the present invention; 
     FIGS. 9A and 9B show shank portions of support brackets for use with the display system of FIG. 8; 
     FIGS. 10A and 10B are, respectively, a cross section and elevation of the standard of FIG. 8; 
     FIG. 11 is a perspective view of a conductive tape and connector for retrofitting a lighted shelf ito a non-powered display case; 
     FIGS. 12A and 12B are, respectively, a perspective and an exploded view of an end cap for use in a retrofitted display case; 
     FIG. 13 a cross section of a plunger for use with the end cap of FIGS. 12A and 12B; and 
     FIGS. 14A and 14B are cross sections of showing alternative configurations of a light fixture constructed in accordance with the principles of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring first to FIG. 1, a first illustrative embodiment of the present invention is shown by way of display case  10 , which may be either free standing or attached to a supporting wall. Sides  12  include power strips  14  mounted into a groove or slot therein. Sides  12  also include a number of spaced apart holes  13  for accepting conventional shelf support pins. Power strips  14  includes a number of spaced apart holes  15  corresponding to holes  13 . Together, holes  13  and  15  accept steel pins  16  to support shelf  17  which may contain under-shelf light fixture  20 . It should be understood the perspective used in FIG. 1 hides one power strip from view, and that both sides of display case  10  include holes  13  and power strip  14 . 
     Power for the display case is provided by low voltage power supply  18 , which converts line voltage to a low voltage of about 12 volts, bu may be as high as about 24 volts depending on the number of lighted shelves installed in display case  10 . A suitable power supply is available from Translite Systems, of San Carlos, Calif. Low voltage power supply  18  is coupled to power strips  14  by connector blocks  19 . Preferably, low voltage power supply  18  is hidden within the base of display case  10 . 
     Light fixture  20 , which is shown in more detail in FIGS. 2-5, includes base  22 , lens  24 , end caps  26 , and lamp holders  28 . Base  22  is mounted to the bottom surface of shelf  17 , and is preferably let into a groove or dado therein, and is attached to shelf  17  by means of mechanical fasteners or a suitable adhesive. Base  22  comprises an extrusion of ABS plastic having a cross section as shown in FIG.  3 . To minimize cost, base  22  is preferably a single extrusion, but bas  22  may be built up from multiple components, such as a track fastened to a wide ‘U’-shaped channel. Base  22  may also be made of polycarbonate, PVC, or other suitably rigid plastic. Alternatively, all or some of base  22  may be made of metal, such as extruded aluminum, in which case insulation must be provided between base  22  and buses  32   a  and  32   b.    
     Light track  31  is preferably adapted to engage a suitable track light lamp holder equipped with halogen or xenon lamps. A low profile lamp holder such as that depicted in U.S. Pat. No. Des. 362,656 is one example of a lamp holder suitable for use with base  22 . The interior of base  22  may be made reflective, such as by the addition of a reflective foil or coating, to help reflect heat and light from the bulbs in lamp holder  28 . 
     Lens  24  is preferably a transparent polycarbonate extrusion designed to distribute the light provided by lamps  28 . To that end, lens  24  may be smooth, textured, or faceted, and may be transparent, translucent, or partially opaque, depending on the specific lighting needs. For example, lens  24  may include longitudinal grooves  37  for focusing the light downward, and may include opaque portion  38  to reduce the amount of horizontally projected light. Lens  24 , includes lip  34  for mating with corresponding shoulder  35  of base  22 . 
     Referring now to FIGS. 4A and 4B, an illustrative embodiment of end cap  26  is described in accordance with the principles of the present invention. End cap  26  includes end cap conductor  40 , tongue  41 , and notch  42 . Tongue  41  is designed to engage or slide into an end of track portion  31  of base  22  as depicted in FIG.  2 . Conductor  40  includes tab  43  which comes into contact with one of conductors  32  when tongue  41  is engaged with light track  31 . Notch  42  is designed to fit over pin  16  inserted into hole  15  in power strip  14  of FIG.  1 . Conductor  40  also includes spring portion  44  disposed in notch  42  to provide for positive electrical contact between pin  16  and conductor  40 . Preferably end cap  26  is injection molded from a suitable thermoplastic, such as Noryl, although PBT or a ABS/polycarbonate blend may also be used. 
     Preferably, end cap  26  is symmetrical with respect to the centerline of tongue  41 , so that a single end cap design may be used for either end of lighting fixture  20 . Alternatively, different end caps may be used at either end; however, it is important that each one of conductors  32  is coupled to a separate end cap FIG. 5 is an exploded perspective view of an illustrative method for constructing end cap  26  in accordance with the principles of the present invention. 
     Power strip  14 , shown in more detail in FIGS. 6A and 6B, is mounted in a vertical groove milled in side  12  of display case  10 , and provides a means of bringing electrical power to shelf  17 . Power strip  14  includes rear housing  61 , front housing  63 , both made of extruded PVC vinyl or an ABS/polycarbonate material, and conductor  65 . Front housing includes holes  15  sized to accept pin  16  of FIG.  1 . Conductor  65 , which may comprise two strips of a conductive material, such as brass or copper, or a single piece having suitable openings along its length, includes one or more tangs  66 . Rear housing  61  has a number of slots, grooves, or ridges which hold conductor  65  in place, such that tangs  66  are juxtaposed behind holes  15  in power strip  14 . When pin  16  is inserted into hole  15 , tangs  66  are deflected by pin  16  thus ensuring good electrical contact. For ease of assembly, rear housing  61  and front housing  63  are preferably designed to snap together. 
     Connector  19  has a cross section similar to that of front housing  63 , so that it may be snapped into rear housing  61  near the bottom of display case  10  of FIG. 1. A through conductor embedded in connector body  74  includes one or more prongs  76  and head  77 . When snapped into rear housing  61 , prongs  76  provide electrical contact with conductors  65  within rear housing  61 . Wire  11  from power supply  18  (see FIG. 1) is coupled to head  76  by a screw, bolt, or other suitable device. 
     It will be apparent from the foregoing description and drawings that the various assemblies described cooperate to provide power from power supply  18  to lamps  28  in lighting fixture  20 . Specifically, electrical current may flow from power supply  18  through wire  11  and connector  19  to conductors  65  inside power strip  14 . Pin  16 , inserted into hole  15  in power strip  14 , contacts tangs  66  of conductor  65 , thereby establishing electrical contact. Notch  42  in end cap  26  accepts a portion of pin  16  protruding from power strip  14  such that spring portion  44  of end cap conductor  40  makes electrical contact with pin  16 . Tab  43  of end cap conductor  40  makes electrical contact with bus  32 , which in turn is electrically coupled to lamp holder  28 . Thus, current flows through conductor  65 , pin  16 , end cap conductor  40 , and light track bus  32  to lamp holder  28 . Current then returns via a similar path through the other bus, end cap, pin, conductor, connector, and wire to power supply  18 , thereby completing an electrical circuit, and providing electrical energy for illuminating lamps  28 . 
     The illustrative embodiment of a display case of the present invention described above is suitable for many types of merchandise displays. However, for reasons of size, flexibility, or aesthetics, display case  10  may not be desirable. An exemplary wall unit including a lighted shelf in accordance with the principles of the present invention is shown in FIG.  8 . 
     Wall unit  80  includes slotted standards  81  spaced at intervals along and fastened to a wall or other suitable structure. Power supply  18  is coupled to standards  81  by means of wires  11  and connectors  83 . If desired, standards  81  and power supply  18  may be hidden behind panels  82 . Gaps between panels  82  provide access to standards  81 . 
     Shelf  17  is the same as described above in connection with FIGS. 2-5 with the addition of brackets  84  on either side. Brackets  84  include shank portion  92 , as shown in FIGS. 9A and 9B and a cantilever portion which is attached to shelf  17  by screws or other suitable fasteners. Pin  85  protrudes from a side of the cantilever portion of bracket  84  and engages notches  42  in end caps  26  to provide an electrical connection between bracket  84  and end cap conductor  40 . Preferably, brackets  84  are powder coated, except for pin  85  and contact area  93  on shank portion  92 . 
     Referring now to FIGS. 10A and 10B, standards  81  include slotted member  96  having a number of slots  97  spaced along its length adapted to accept shank portion  92  of bracket  84  and support bracket  84  in a cantilevered fashion. Standard  81  also includes conductors  98  disposed behind slotted member  96 . Conductors  98  include tangs, or tabs,  99  juxtaposed behind slots  97  so that when shank portion  92  of bracket  84  is engaged with slot  97 , contact area  93  makes electrical contact with tabs  99 . Preferably, standard  81  is adapted to accept a rear housing as used in power strip  14  of FIGS. 6A and 6B, thereby simplifying manufacture. 
     Thus, it will be understood that standards  81 , brackets  84 , and light fixture  20  cooperate to complete an electrical circuit between power supply  18  and one or more lamps in light fixture  20 . Specifically, the circuit comprises power supply  18 , wire  11   a , standard  81  a with internal conductors  98 , bracket  84   a  with pin  85   a , end cap  26   a , and bus  32   a  (FIG.  3 ), and returning via bus  32   b , end cap  26   b , bracket  84   b  with pin  85   b , standard  81   b , and wire  11   b.    
     The illustrative embodiments described thus far are suitable for use in new installations, or in connection with a major remodeling, or overhaul, of an existing display. An embodiment of the invention for use in retrofitting an existing display is now described in connection with FIGS. 11-13. Retrofitting an existing display case would require a fairly extensive amount of work to create a groove in the side of the display case and install a power strip, such as that in FIGS. 6A and 6B. As an alternative, conductive tape  112 , such as that shown in FIG. 11 may be adhered to the inside of surface of the display case sides. Connector  114  provides a means of attaching a power supply to conductive tape  112 . 
     A retrofit system also uses a slightly modified end cap. End cap  120 , is identical to the end cap of FIGS. 4 and 5, except that end cap  120  includes groove  122  adjacent to notch  124 . Spring loaded pin  132 , shown in FIG. 13, is inserted into notch  124  so that saddle  134  fits into groove  122 . The retrofit shelf is put in the display case so that plunger  136  of spring loaded pin  132  contacts one of conductive tapes  112 . A circuit is thus completed through conductive tapes  112 , spring loaded pins  132 , and the light fixture. 
     FIGS. 14A and 14B show alternative embodiments of an under shelf light fixture in accordance with the principles of the present invention. As in the other embodiments shown herein, the light fixture includes base  141 , lens  143 , and end caps (not shown). These embodiments show light track  145  at different positions on base  141 . Base  141  also includes a portion  146  having parabolic shape for focusing light from lamps  147  as may be desired. One skilled in the art will understand that the light fixtures of FIGS. 14A and 14B utilize distinct left and right end caps, in contrast to the previous embodiments, which utilize a single reversible end cap. 
     While a preferred embodiment of the present invention has been described herein, it will be apparent to one skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. For example, combining structural elements, substituting materials, modifying shapes of components, and interchanging prongs and sockets are exemplary modifications which would not fall outside the scope of the present invention. 
     Therefore, it is intended that the appended claims cover all such changes and modifications which fall within the true spirit and scope of the invention.