Abstract:
A refrigerated display case and process of illuminating the case is provided. The display case has a support mullion ( 22 ) positioned in proximity to a glass door. A fluorescent lamp ( 34 ) is located within a lateral opening along either side of the support mullion ( 22 ). A diffusing lens ( 32 ) is positioned within the lateral opening, opposite the lamps, scattering the light as it passes through from the side of the mullion and through the diffusing lens ( 32 ). The glass door provides a reflective surface which reflects a substantial portion of the scattered light towards the interior space of the display case.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Serial No. 60/137,989 filed on Jun. 7, 1999 and which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention is generally directed towards a display cabinet and particularly a commercial display cabinet having an internal lighting system and assembly. 
     BACKGROUND OF THE INVENTION 
     A wide variety of commercial display cabinets exists. One common type of a refrigerated display cabinet includes a cabinet frame which extends generally about the periphery of the front of the display cabinet. The frame includes an upper frame member, a lower frame member, two laterally spaced side frame members extending vertically between the upper and the lower frame members, and a center mullion which extends vertically between the upper frame member and the lower frame member and connected thereto. The mullion provides support for the cabinet frame, associated doors, and also provides a sealing surface against which portions of the door assemblies engage and seal for effective sealing of the refrigerated cabinet. Typically, mullions are also equipped with electrical conduits for delivering electrical power to anti-condensation devices for the door assemblies and for a fluorescent lighting fixture associated with the mullion. 
     One popular design for a refrigerator or freezer cabinet frame assembly provides for one central mullion, a door stop for a pair of doors, each door pair member being mounted to a respective front edge of the display cabinet. Thus, the doors open from the front center of the cabinet with the left opening door pair member having hinge pins on the left side of the door and the right opening door pair member having hinge pins on the right side of the door. The central mullion provides a gasket covered surface and support for engaging and securing the doors in a closed position. 
     A fluorescent light is typically mounted on the rear surface of the center mullion so as to illuminate the interior of the display cabinet. Proper illumination of the merchandise present within the display cabinet is important so as to maintain an attractive product appearance and to allow a customer to visually locate merchandise within the cabinets prior to opening the cabinet door. Various louvered reflectors have been disposed inside the cabinet to redirect the light within the cabinet. As such, it is desirable to provide a refrigerated display cabinet having a lighting assembly which improves the illumination of the cabinet merchandise. 
     The construction and components used in an illuminated refrigeration or freezer display cabinet are well known in the art. For instance, U.S. Pat. Nos. 5,471,372 to Mamelson et al. and 5,879,070 to Severloh, are directed to the construction of lighted refrigerated display cases, these references being incorporated herein by this reference. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, an improved refrigerated display case having a central vertical mullion spaced opposite the handle portion of adjacent side pivoted doors is provided. The central mullion is secured at its top and its bottom to the cabinet frame, and a pair of rectangular doors are mounted to opposite sides of the frame on vertical hinge axes for swinging movement between open positions and closed positions. In the closed position, the central mullion defines a front surface adapted to seal with the rectangular door inner surface. The central mullion is generally rectangular and hollow and has a front surface facing outwardly of the cabinet assembly, a back surface facing inwardly of the cabinet assembly, the two sides of the mullion being open and adapted for receiving a fluorescent lighting assembly. The lighting assembly positions a fluorescent bulb within each side of the center mullion whereby the bulb may be easily accessed and replaced. This placement also allows a significant portion of the bulbs&#39; illumination to be directed towards and reflect from the interior glass door surface and thereby increase the effective illumination within the cabinet&#39;s interior. An outer protective lens is removable to access the light assembly components. In one embodiment of the invention, the leading edge of each door is canted outwardly forming an approximate 77.5 degree angle relative to an axis perpendicular to a plane defined by a rear cabinet wall. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of a display case in accordance with the present invention; 
     FIG. 2 is a perspective view in partial section of a central support mullion and associated doors as seen from an interior of the case; 
     FIG. 3 is a sectional view taken along line  3 — 3  of FIG. 2; 
     FIG. 4 is a perspective view of an embodiment of a central mullion with details of the light assembly components; 
     FIG. 5 is a sectional view taken along line  5 — 5  of FIG. 4; and 
     FIG. 6 is a sectional view similar to FIG. 5 showing an alternative embodiment of a lens construction. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention, which broader aspects are embodied in the existing construction. 
     In describing the various figures herein, the same reference numbers are used throughout to describe the same apparatus. To avoid redundancy, detailed descriptions of much of the apparatus once described in relation to a figure is not repeated in the descriptions of subsequent figures, although such apparatus is labeled with the same reference numbers. 
     In reference to FIG. 1, a refrigerated display case  10  is provided having a cabinet which defines an enclosure having an interior space accessible via a front opening. A pair of doors  12  and  14  is supported by the cabinet and may be selectively positioned to close the cabinet&#39;s front opening or allow access to the interior space of the cabinet&#39;s enclosure via the front opening. Each door  12 ,  14 , includes a panel  16  that is transparent or translucent to permit viewing of the product within the enclosure and is movable to provide access to the product. As illustrated in the figures, doors  12  and  14  are mounted to opposite sides of case  10  in a conventional manner for swinging movement between an open position and a closed position. However, the hinge portions of the doors could be installed along the center mullion so that the doors open from opposite ends of the display case. Handles  13  are used to engage and pivot the doors  12  and  14 . If desired, the movable doors could be provided by one or more sliding glass doors. 
     An inner perimeter of each door defines a conventional seal and gasket arrangement to provide a substantially air tight thermal barrier for case  10  when the respective doors are closed. As seen in reference to FIG. 3, a portion of door gasket  40  carries a magnet  42  which helps maintain the pivoting doors  12  and  14  in a closed position. 
     As seen in reference to FIG. 2, a central mullion is designated generally by the numeral  20  and extends the height of the enclosure and is positioned opposite a leading edge of door  12  and door  14  when oriented to close the front opening of the cabinet. The mullion  20  extends the height of the enclosure and is positioned opposite a leading edge of each of the individual doors  12  and  14 . The mullion has a front surface  24 , a back surface  28  opposite the front, and a pair of opposed sides extending between the front and the back, each side defining a lateral opening  26 . 
     As explained more fully below and shown in FIG. 5 for example, mullion  20  defines a front face  24  which is formed of a magnetic material that will attract the magnet  42  of the door gaskets. As shown in FIGS. 4 and 5 (chain-dashed line), mullion  20  further defines a pair of integral upper flanges  21  which are used to secure the mullion to the cabinet front, each flange  21  defining an aperture  23  for attaching the mullion to the cabinet. Each side edge  27  of front face  24  engages a respective support member  22 , which is desirably fabricated as a plastic extrusion. Support member  22  defines a front surface  25  and a rear surface which defines mullion back surface  28 . A resistive wire  29  provides a heating element disposed against the inner surface of the mullion face to reduce condensation on the portion of the mullion&#39;s face  24 , which is exposed to the external environment when the doors are opened. Alternatively, insulation (not illustrated) may be installed for this same purpose as is conventional within the art. 
     As best seen in reference to FIGS. 3 and 4, a light fixture  30  is supported within each lateral opening  26  defined by support member  22  along either side of the mullion. Each light fixture  30  is configured and disposed for receiving and supporting an illumination source such as a fluorescent bulb  34 . As shown in FIG. 3, a mounting clip  37  receives the electrical end prongs  38  of each bulb  34 . A light diffuser such as a diffusing lens  32  is positioned within the lateral openings  26  and opposite the light fixture  30  and bulb  34  so as to diffuse the direction and intensity of light emanating from the illumination source. Lens  32  covers the lateral openings  26 . 
     As seen in reference to FIG. 4, the front face  24  of center mullion  20  engages the support member  22  along either edge  27  of front face  24 . A pair of mounting flanges  21  extend normally with respect to the main body of front face  24  and over a portion of the mullion&#39;s interior and define a hole  23  for attaching the mullion to the display case&#39;s cabinet. Each extruded support member  22  provides a U-shaped housing, the interior of which is adapted for receiving the light fixture  30 . In reference to the orientation seen in FIGS. 3 and 5, the lateral opening  26  along each side of the mullion  20 , is defined by support member  22  is configured to and allow each bulb  34  to emit light through the respective lateral opening  26 , passing through diffusion lens  32 . As seen in FIGS. 3 and 5, the diffusing effect of lens  32  is indicated schematically as a single directional ray of light, designated as “L”, which is diverged into multiple rays (“LL”) upon passing through the lens  32 . For clarity of illustration, only a single ray “L” is shown diverging into multiple rays “LL”. 
     Lens  32  may be provided by a flexible curved piece of translucent plastic which is removably held in a tensioned fashion by support member  22 . As best seen in reference to FIG. 5, it has been found useful to provide a first ridge  50  and a second ridge  52  as part of support member  22 . Ridges  50 ,  52  generally define therebetween lateral opening  26 . Ridges  50  and  52  are used to engage respective correspondingly shaped first notch  54  and second notch  56  formed near opposite edges of the embodiment of lens  32  shown in FIG.  5 . Preferably, lens  32  has sufficient flexibility that a simple lens  32  may be easily inserted and removed by providing a slight compressive action to the terminal ends of the lens  32 . 
     In an alternative configuration of lens  32  and support member  22  shown in FIG. 3 for example, recessions  31  and  33  are formed in the opposite side edges of support member  22  and configured to receive the respective side edges of lens  32 . A boss  35  is provided along the exterior surface of lens  32  to provide a means of gripping lens  32  to pry it from engagement with support member  22 . 
     Yet another alternative configuration of lens  32  is shown in FIG.  6 . An inner surface of lens  32  defines a plurality of inwardly directed projections  60 . Each projection  60  extends along the length of the lens  32  and may be integrally formed with lens  32 . Collectively, projections  60  define a baffle or series of blind-like slats which alter the direction and intensity of emitted light in comparison to a lens  32  without the projections. 
     As seen in FIG. 6, projections may be substantially perpendicular to reference line A so as to achieve a substantially uniform distribution of light horizontally across the front edges of the display shelves. However, depending upon the desired illumination effect, the spacing between the projections, the number of projections, the relative angles of one or more of the projections, the size, thickness, and length of the projections may be modified. As further seen in reference to FIG. 6, the projections  60  may extend inwardly different lengths, depending upon location, so as to affect the amount and direction of transmitted light. 
     The projections  60  do not alter the pathway of light rays (L) which pass between the opposite projections. However, rays (L) which strike a single projection  60  will partially block and alter the resulting scatter light “LL”. As a consequence, projections  60  serve to soften and lower the intensity of emitted light rays which pass through or impact an internal projection  60 . Further, there is a corresponding increase in the relative amount and intensity of the light fractions which are transmitted between the projections. The improved gradient of transmitted light prevents over-illumination of product immediately adjacent the light source and improves the illumination quality of product which is more distant from the light source. 
     In accordance with this invention, it has been found that the glass door will reflect a significant portion of the light emitted from a lateral opening  26 , redirecting the reflected light towards the interior of the cabinet. The reflected light from the door&#39;s interior surface provides an even, front illumination source of reflective light for merchandise displayed within the cabinet. Additional lighting is provided directly from light passing through the diffuser lens. This combination of lighting provides for an even product illumination. 
     If desired, support member  22  can be provided from a transparent or translucent material such as polycarbonate or other clear or translucent plastic. The light transmitting support member will allow a broader distribution pattern of light from the mullion, the distribution pattern not being limited to the physical dimensions of the lateral opening. Alternatively, support member  22  may be coated with a reflective or non-absorbing paint so as to increase the efficiency of the light source. 
     In the illustrated embodiment shown in FIG. 3 for example, a reference line “A” is defined to extend perpendicular to a rear plane defined by the rear wall (not shown) of the cabinet. Line “P” is used as a reference point, reference line “P” being parallel to the rear wall plane. Reference line “A” bisects the front cabinet face along a midpoint of a mullion. In the illustrated embodiment, this midpoint of the mullion also defines a point along the front edge of the cabinet mullion which extends outwardly and forwardly the greatest distance from the interior of the cabinet. 
     As seen in reference to FIG. 3, an angle α is formed between the intersection of reference line “A” and planes “D 1 ” and “D 2 ” defined respectively by the interior perimeter surfaces  15  and  17  of doors  12  and  14 . Angle α is desirably between about 75 degrees to about 90 degrees, preferably between about 75 to 85 degrees, still more preferably between 76 to 79 degrees and still more preferably between 77 to 78 degrees. In the illustrated embodiment, angle α is about 77.5 degrees. When angle α is 90 degrees, surfaces  15  and  17  are parallel to plane P. 
     For the purposes of this invention, when angle α is about 90 degrees, a parallel arrangement exists between the plane of the inner door frame and the plane P defined by the rear wall of the cabinet. In other words, in this parallel arrangement, bulb(s)  34  provide(s) a substantial amount of illumination that is desirably reflected from the interior door surface  15  and/or  17  towards the display area of the shelves inside the case  10 . The diffusing lens  32  directs a portion of the light from the side of the mullion to the door surface at a sufficient angle to create a reflected light component which is directed towards the interior of the cabinet. However, by reducing the value of angle α, it has been further found that a greater proportion of the illumination striking the interior door surface may be reflected towards the cabinet display area. 
     It is also envisioned that the interior door surface may be provided by a piece of angled or curved glass or other transparent or translucent material. For instance, as viewed from the interior of the cabinet, a slight, generally concave curvature may be provided to the reflecting portion of the door. Such a curvature may provide a more efficient reflective surface in the sense that it increases the amount of light reflected to the interior of the display case. Further, the curved door surface could be used to favorably direct or concentrate the reflected light to a desired region of the cabinet. A similar effect may be achieved by having one or more angled facets defined by the interior reflective face of the door. 
     The present invention provides a useful process for improving the illumination of a cabinet. By directing discharged light toward the interior surface of the door, the door may provide a reflective surface which redirects the light towards the interior space of the cabinet. The position of the reflective door surface, relative to the illumination source, may be varied to increase the amount of light which is reflected. 
     The interior door surface may further define a curved or multifaceted reflective surface to increase the amount of reflected light and/or the direction of the reflected light. Further, a coating layer may also be applied to the interior door surface to increase the surface&#39;s reflective properties. Such coatings, as known in the art, still allow the interior of the display case to be viewed through the transparent door. 
     Prior art lighting systems for similar cabinets, make use of a single light fixture positioned upon the rear mullion surface that faces the interior of the cabinet. The resulting lighting is uneven and has prompted the use of various louvers and reflectors as mentioned in the background section above. 
     The present invention, using a standard size mullion, provides for a dual bulb lighting, effectively doubling the amount of available light. Further, by directing the light through a diffuser, harsh illumination is avoided. The lighting is enhanced further by positioning a reflective surface of the door relative to the light fixture to reflect additional light towards the display areas of the cabinet. Projections defined along the interior surface of the diffuser provide yet an additional light distributing mechanism to increase illumination along the entire front display region while minimizing harsh glare or uneven illumination patterns. The resulting light provides a balance to the illumination, minimizing shadows and harshness associated with unidirectional lighting systems. 
     While the illustrated embodiments discussed above are in reference to a single center mullion cabinet construction, the advantages of the improved lighting of the present invention may be used with different styles of cabinets. For instance, wide refrigeration or freezer units may have multiple mullions, each mullion simultaneously engaging the support hinge of one door along one side of the mullion while the opposite mullion side engages the handled door edge of an adjacent door. The multiple mullions can provide the side emitting light features and construction as described above to enhance the illumination and light qualities of the display cases. 
     Additionally, the display case need not be refrigerated to take advantage of the center mullion side lighting assembly of the present invention. Although desired embodiments of the invention have been described using specific terms, materials, and methods, such description is for illustrative purposes only. The words used are words of description rather than of limitation. It is to be understood that changes and variations may be made by those of ordinary skill in the art without departing from the spirit and scope of the present invention which is set forth in the following claims. In addition, it should be understood that aspects of the various embodiments may be interchanged, both in whole or in part.