Illuminated shelving

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.

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'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'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.

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 32a and 32b.
 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 11a, standard 81 a with internal
 conductors 98, bracket 84a with pin 85a, end cap 26a, and bus 32a (FIG.
 3), and returning via bus 32b, end cap 26b, bracket 84b with pin 85b,
 standard 81b, and wire 11b.
 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.