Abstract:
A lighting arrangement using LEDs that has an elongated translucent diffuser having a flat upper surface along the length of the diffuser. The transverse cross-section of the elongate translucent diffuser may have various shapes, all having substantially flat tops, including but not limited to quadrangular, rectangular, trapezoidal, and non-isosceles variations of these shapes. The elongated translucent diffuser is mounted on an elongated housing of substantially the same length to support the diffuser. The elongated housing may be solid or hollow and may contain the LEDs and circuit board, or the LEDs and circuit board may be contained within the elongated translucent diffuser. The LEDs are configured to transmit light through the diffuser so that the emitted light simulates light from a traditional neon tube.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 61/243,800 filed on Sep. 18, 2009, the entirety of which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to a sign, and more particularly to an illuminated sign incorporating an elongate diffuser or waveguide which provides a novel and attractive surface for emitting substantially uniform light. 
     Signs for storefronts and the like are well known throughout the art. For instance, signs for indicating whether a particular business is open, i.e., open signs, and the like are well known. Such signs have traditionally utilized neon for illumination of the sign. In such signs, a number of tubes are arranged to spell out the word or words desired such as, e.g., “OPEN”. Such tubes, traditionally round hollow glass, are filled with neon, argon, xenon, or other gases, and an electrical charge is applied to the gas by way of a pair of opposed electrodes at either end of the tube to thereby illuminate the gas and the tube. Such signs, however, suffer from a number of disadvantages. Neon tubes tend to be very brittle and susceptible to accidental breakage. During the manufacture of a neon sign the glass tubes, typically manufactured as straight linear hollow tubes, are heated and deformed into the illuminated elements of the sign, for example, to spell out the word “OPEN,” but must still retain an unobstructed hollow center with one or more ends for applying an electrical charge. The process is thus limited by the constraints of illuminating the tube with neon gas within, and the constraints imposed by the available traditional neon glass tubing which limits the design and appearance of the finished sign and requires a substantially complex fabrication process. Further, neon tubing is relatively expensive and thus replacement of the tubes is undesirable and cost prohibitive. 
     As such, it has become known to provide signs that simulate the appearance of neon tubing by using a series of light emitting members such as, for example, light emitting diodes (“LEDs”) arranged along the length of a housing and directed to emit substantially uniform light at a diffuser or waveguide to thereby illuminate the waveguide in a manner that simulates the appearance of neon. Such constructions are advantageous with respect to traditional neon signs in that the energy needs of these signs are quite small thereby reducing costs to the user. Further, as compared to traditional neon signs, the waveguides and housing may be produced from a relatively lighter weight and more malleable or moldable material other than glass, such as a plastic. However, such signs, despite the potential for modification of the waveguide shape made of more malleable material, continue to mimic the rounded surface of a glass tube. Diverging from the rounded light emitting surface of the neon glass tube can allow designs that are novel and thus stand out from traditional neon signs, thus becoming more noticeable and potentially more attractive to the human user. In addition, the waveguide can be designed to be more structurally sound, and can be fabricated without relying on bending or deforming glass in a secondary manufacturing step. Thus, it is desired to provide a sign that overcomes each of the foregoing disadvantages while maintaining the high quality illumination provided by the sign. 
     SUMMARY OF THE INVENTION 
     The present inventors have recognized that a significant feature of an illuminated sign is the structure and appearance of the light-emitting waveguide. Providing a waveguide that is practical, structurally and in terms of material cost, and novel or attractive, can positively affect the user&#39;s experience with the illuminated sign. 
     Specifically, the invention contemplates a simulated neon light including at least one elongated translucent diffuser or waveguide having an inner surface, an outer surface, and a hollow interior. The outer surface of the diffuser has a flat top portion extending substantially over the length of the elongated translucent diffuser. The light includes a housing that is configured for attachment to the translucent diffuser, and a series of light emitting diodes contained within the housing and aligned with a long axis of the elongated translucent diffuser. With this construction, the light emitting diodes when energized emit light that strikes the inner surface of the elongated translucent diffuser, such that a portion of the light is diffused and emitted by the flat portion of the outer surface. An electrical power source energizes the light emitting diodes. The simulated neon light thus has a novel look for attracting the user and enhancing their visual experience. 
     The housing may have an interior space and at least one open side, or the diffuser may be mounted to a support structure that is substantially solid. The diffuser may have a closed boundary extending substantially over the length of the diffuser and forming a hollow interior. The diffuser may be in the form of an assembly having a top wall portion and a securably attached bottom wall wherein the bottom wall may be a transparent or a translucent material. The diffuser may have a bottom wall that may be assembled so as to allow insertion of components, and constructed with minimal diffusive materials. Alternatively, the bottom wall may be opaque to light to allow light to only be emitted from the top wall portion of the diffuser when LEDs are mounted within the diffuser. The diffuser may have two substantially flat sides extending substantially over the length of the elongated translucent diffuser on either side of the flat top wall. The diffuser may have sides that are substantially orthogonal to the top wall or that are at an angle to the top wall. Mounting structure for attaching the LEDs may be integrated with the housing or with the diffuser. 
     Other aspects, features, and advantages of the invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating certain embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the invention is illustrated in the accompanying drawings in which like reference numerals represent like parts throughout. 
       In the drawings: 
         FIG. 1  is a isometric view of a sign according to the present invention; 
         FIG. 2  is an isometric view of a simple linear segment of a sign such as that shown in  FIG. 1  according to the present invention, showing a portion of an elongated housing and a light emitting diffuser or waveguide; 
         FIG. 3   a  is a cross-sectional view of the sign segment of  FIG. 2  according to the present invention, showing an embodiment of a 3-sided waveguide and the attached housing; 
         FIG. 3   b  is a cross-sectional view similar to  FIG. 3  showing an embodiment of a 4-sided waveguide and the attached housing; 
         FIG. 4   a  is a cross-sectional view of the 4-sided waveguide as shown in  FIG. 3   b;    
         FIG. 4   b  is a cross-sectional view of another embodiment of a 4-sided waveguide similar to that shown in  FIG. 4   a;    
         FIG. 4   c  is a cross-sectional view of yet another embodiment of a 4-sided waveguide similar to that shown in  FIGS. 4   a  and  4   b;    
         FIG. 4   d  is a cross-sectional view of  4   a  3-sided diffuser like that shown in  FIG. 3A ; 
         FIG. 5   a  is a cross-sectional view similar to  FIG. 3   a  showing a 3-sided waveguide and housing having a substantially rectangular configuration; 
         FIG. 5   b  is a cross-sectional view similar to  FIG. 5   a  showing a 5-sided waveguide and housing having a substantially trapezoidal configuration; 
         FIG. 6   a  is a cross-sectional view similar to  FIG. 3   b  showing a 4-sided waveguide and housing having a substantially rectangular configuration; 
         FIG. 6   b  is a cross-sectional view similar to  FIG. 6   a  showing a 5-sided waveguide and housing having a substantially trapezoidal configuration; 
         FIG. 7  is a cross-sectional view showing an embodiment of the elongate housing without a waveguide, such as is incorporated in the assembly views shown in  FIGS. 1-3   b  and  5   a - 6   b;    
         FIG. 8   a  is a cross-sectional view similar to  FIGS. 3   a ,  3   b  and  5   a - 6   c , showing an embodiment of a 4-sided substantially rectangular waveguide and an alternate embodiment of the housing; 
         FIG. 8   b  is a cross-sectional view similar to  FIG. 8   a , showing an embodiment of a 3-sided waveguide and an alternate embodiment of the housing, with the LED and circuit board mounted within the waveguide; 
         FIG. 9   a  is a cross-sectional view similar to  FIGS. 3   a ,  3   b  and  5   a - 6   c , showing an embodiment of a 4-sided substantially rectangular waveguide with the LED and circuit board mounted within the waveguide and attached to a substantially solid housing; 
         FIG. 9   b  is a cross-sectional view similar to  FIG. 9   a , showing an embodiment of a 3-sided waveguide and a substantially solid housing; 
         FIG. 10   a  is a cross-sectional view similar to  FIGS. 9   a  and  9   b , showing an embodiment of a 4-sided substantially rectangular and a substantially solid housing that is narrower than the waveguide; 
         FIG. 10   b  is a cross-sectional view similar to  FIG. 10   a , showing an embodiment of a 4-sided substantially rectangular waveguide and a substantially solid housing that is wider than the waveguide; 
         FIG. 10   c  is a cross-sectional view similar to  FIGS. 10   a  and  10   b , showing an embodiment of a 3-sided waveguide and a substantially solid housing that is wider than the waveguide; 
         FIG. 11   a  is a cross-sectional view similar to  FIGS. 9   a - 10   c , showing an embodiment of a 3-sided waveguide and an alternate embodiment of a substantially solid housing; 
         FIG. 11   b  is a cross-sectional view similar to  FIG. 11   a , showing an embodiment of a 3-sided waveguide and another alternate embodiment of a substantially solid housing; 
         FIG. 12  is a cross-sectional view showing an embodiment of a 4-sided substantially rectangular waveguide with the LED and circuit board attached to the outside the waveguide with the circuit board attached to the housing; 
         FIG. 13   a  is a cross-sectional view showing an embodiment of a 3-sided substantially rectangular waveguide with the LED mounted within the waveguide on a circuit board that also serves as a wall of the housing; 
         FIG. 13   b  is a cross-sectional view showing an embodiment of a 4-sided substantially rectangular waveguide with the LED and circuit board mounted within the waveguide without an external housing; 
         FIG. 13   c  is a cross-sectional view showing an embodiment of a 4-sided substantially rectangular waveguide with the LED mounted within the waveguide on a circuit board secured to the housing; 
         FIG. 14   a  contains cross-sectional views similar to  FIG. 3   a  showing the LED and circuit board assembly positioned at three different locations within the waveguide and housing assembly; and 
         FIG. 14   b  contains cross-sectional views similar to  FIG. 3   b  showing the LED and circuit board assembly positioned at three different locations within the waveguide and housing assembly. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the Figures, and initially to  FIGS. 1-7 , this invention relates to a lighting arrangement, such as an arrangement used to simulated neon light, which uses light emitting diodes (LED&#39;s)  27  as a light source to illuminate simulated neon lights, which are generally represented at  20 . 
     A representative embodiment of the present invention is a sign  10 , illustrated in  FIG. 1  as an “OPEN” sign that is formed of a series of neon lights  20 . However, it is understood that simulated neon lights  20  may be configured in a variety of shapes to display a variety of messages and designs of various colors and sizes as a sign or otherwise. It is also understood that the present invention may be used in any application, and that its use in the context of a simulated neon sign is but one illustrative example of the many applications in which the present invention may be used. In this representative embodiment, sign  10  includes a frame  16  configured for mounting the simulated neon lights  20 . The simulated neon lights  20  in this embodiment are the quadrilateral border and letters ‘O’, ‘P’, ‘E’, and ‘N’ as shown in  FIG. 1 . 
       FIG. 2  shows a portion of one of the simulated neon lights  20 , which includes a housing  26  and a waveguide diffuser  24  having a long axis  22 , a width  42 , and a length  28  wherein the diffuser  24  is securably attached to the housing  26 . The waveguide  24  has a substantially flat upper surface  11  and substantially flat side surfaces  13 . Housing  26  is preferably constructed from an opaque, lightweight and durable material such as plastic. Alternatively, housing  26  may be constructed from a relatively lightweight metal such as aluminum or the like through an extrusion or similar such process. Diffuser  24  is preferably constructed from a translucent lightweight and durable material such as plastic that has the quality of being able to diffuse light. In one embodiment the diffuser  24  may be tinted to emit a different color of light, and may have a shiny or glassy appearance. Alternatively, diffuser  24  may be constructed of glass, tinted or otherwise. 
     Referring now to  FIG. 3   a , a transverse cross-section of the simulated neon light  20  is shown having a three-sided diffuser  24  attached to a housing  26  wherein the housing  26  contains a series of LEDs  27  securably attached to an LED mounting structure, such as a circuit board  29 . The LED mounting structure  29  may be securably attached to the housing  26  in any satisfactory manner. The LEDs  27  are energized by a power supply such that the LEDs  27  emit a light that is transmitted through the diffuser  24 . In the embodiment shown in  FIG. 3   a , the diffuser  24  has an open bottom such that light emitted from the LEDs  27  passes into the interior of the diffuser  24  and impinges directly on the top wall  11  and side walls  13 . 
     In another embodiment as shown in  FIG. 3   b , a similarly configured diffuser, shown at  25 , has a closed configuration. In this embodiment, the diffuser  25  is in the form of a four-sided substantially rectangular waveguide attached to the housing  26  that contains a series of LEDs  27  securably attached to an LED mounting structure  29 . In some embodiments, the LED mounting structure  29  is integrated with the housing  26  as will be described in detail below. 
     Referring now to  FIG. 4   a , a transverse cross-section of the closed four-sided diffuser  25  is shown having a contiguous (i.e. closed) inner surface  32  with an outer surface  34  forming a hollow interior  36 . The closed translucent diffuser  25  has a substantially flat bottom wall  38  having ends  39 , and a top wall  40  connected to the bottom wall ends  39  by side walls  41 , forming interior  36 . The bottom wall  38  is integrated with the top wall  40  and the side walls  41 . 
     Referring to  FIGS. 4   a - 4   b , in one embodiment if the waveguide  25 , the bottom wall  38  may be integral and it may consist of the same material as the top wall as shown in  FIG. 4   a . Alternatively, referring specifically to  FIG. 4   b , the bottom wall  38  may be formed separately and securably attached to the top wall  40 . In this embodiment, the bottom wall  38  may consist of a different material than the top wall  40  and side walls  41 . The bottom wall  38  may extend across the entire width  42  of the opening formed by the top wall  40  and side walls  41 , as shown in  FIG. 4   b.    
     Referring now to  FIG. 4   c , in yet another embodiment the bottom wall  38  may extend across the width  44  of the opening defined by the top wall  40  and the inside surfaces of the side walls  41 , such that the bottom wall  38  is extends between and is secured to the inside surfaces of the side walls  41  at an elevation flush with the bottom ends of the side walls  41 . Other embodiments that are not shown may have differing configurations of the top wall and bottom wall. 
     Diffuser bottom wall  38 ,  42 ,  44  is preferably constructed from a lightweight and durable material such as plastic that has the quality of being able to diffuse or transmit light, and may be tinted to emit a different color of light. In one embodiment the material of the bottom wall  38 ,  42 ,  44  may be the same as the top wall  40  and/or side walls  41 . In another embodiment the bottom wall  38  may be a material different than that of the top wall  40  and/or side walls  41 . In yet another embodiment the bottom wall  38 ,  42 ,  44  may be glass. 
     Diffuser top wall  40  is preferably constructed from a lightweight and durable material such as plastic that has the quality of being able to diffuse light, which may be tinted to emit a different color of light, and may have a shiny or glassy appearance. Alternatively, diffuser top wall  40  may be constructed of tinted glass. 
     Referring now to  FIG. 4   d , in one embodiment the diffuser  24  may be open, i.e. it may have a channel shape defining a downwardly open slot extending along its length such that the diffuser  24  is three-sided when viewed in cross-section. The open diffuser  24  is shown to have a non-contiguous (i.e. open) inner surface  33  with an outer surface  35  forming an interior  37  and a flat open side  31  having bottom edges  46  separated by a distance  48 . In addition, the outer surface  35  has a substantially flat top surface  11  and substantially flat side surfaces  13 . 
     Turning now to  FIG. 5   a , in one embodiment of the present invention, an open diffuser  70  mounted on housing  26  may have a transverse cross section that forms a three-sided substantially rectangular diffuser  70  with an open bottom aperture  39 , substantially flat sides  13 , and a substantially flat top  11 . The diffuser  70  may also have substantially rounded corners  17 . In another embodiment, the corners  17  are not rounded but instead are substantially sharp. In yet another embodiment the diffuser may have sides  13  of unequal height producing a cross-section that is an open non-isosceles quadrangle rather than an open rectangle. 
     Referring to  FIG. 5   b , in another embodiment an open diffuser  72  mounted on housing  26  may have a transverse cross section that forms an open substantially trapezoidal diffuser  72  with an open bottom aperture  39 , substantially flat sides  13 ′, and a substantially flat top  11 ′. The diffuser  72  may also have substantially flat vertical portions of the sides  15  to mate with facing shoulders defined by housing  26 . In another embodiment the sides  13  may not have vertical portions  15  (not shown). The diffuser  72  may also have substantially rounded corners  17 . In another embodiment the corners  17  are not rounded but instead are substantially sharp. In yet another embodiment the diffuser may have sides  13  of unequal height producing a cross-section that is an open non-isosceles trapezoid rather than the open isosceles trapezoid that is shown. 
     Turning now to  FIG. 6   a , in one embodiment a closed diffuser  80  mounted on housing  26  may have a transverse cross section similar to  FIG. 4   a , that forms a closed four-sided substantially rectangular configuration with a flat bottom wall  38 , substantially flat sides  13 , and a substantially flat top  11 . The diffuser  80  may also have substantially rounded corners  17 . In another embodiment the corners  17  are not rounded but instead are substantially sharp. In yet another embodiment the diffuser may have sides  13  of unequal height producing a cross-section that is a non-isosceles quadrangle rather than a rectangle. 
     Referring to  FIG. 6   b , in another embodiment a closed diffuser  82  mounted on housing  26  may have a transverse cross section that forms a closed substantially trapezoidal configuration with a flat bottom wall  38 , substantially flat sides  13 , and a substantially flat top  11 . The diffuser  82  may also have substantially flat vertical portions of the sides  15  to mate with facing shoulders defined by housing  26 . In another embodiment the sides  13  may not have vertical portions  15  (not shown). The diffuser  72  may also have substantially rounded corners  17 . In another embodiment the corners  17  are not rounded but instead are substantially sharp. In yet another embodiment the diffuser may have sides  13  of unequal height producing a cross-section that is an open non-isosceles trapezoid rather than the open isosceles trapezoid that is shown. 
     Referring now to  FIG. 7 , one embodiment of the housing  26  has an open side  58 . A transverse cross-section of housing  26  is shown having side walls  52 , and a bottom  54  forming an interior  56  and the open side  58 . The housing  26  may have arms  60  having a width  55  narrower than the width of side walls  52 . Arms  60  are either securably attached or integral to walls  52  and arranged so that the juncture of the arm  60  with the wall  52  forms a shoulder  62  on the inner surface of the wall  52 . The shoulders  62  are configured to receive the diffuser in aperture  58  as shown, for example, in  FIG. 3   a  and  FIG. 3   b.    
     Turning to  FIG. 8   a , in another embodiment  90 , the housing  26  has top edges  64  which receive the diffuser  25  to attach the housing  26  to the waveguide bottom wall  38 . 
     Referring now to  FIG. 8   b , in yet another embodiment  100 , the housing  26  has top edges  64  which receive the open diffuser  24  to attach the housing  26  to the waveguide bottom edges. 
     Turning to  FIG. 9   a , in another embodiment  110 , the housing  26 ′ is substantially solid and has arms  160  and a surface  126  configured to receive the closed diffuser  25 . The closed diffuser  25  contains the LEDs  27  and supporting structure  29 . 
     Referring now to  FIG. 9   b , in another embodiment  120 , the housing  26 ′ is substantially solid and has arms  160  and a surface  126  configured to receive the open diffuser  24 . The open diffuser  24  contains the LEDs  27  and supporting structure  29 . 
     Referring to  FIGS. 10   a - 10   c , the embodiments  130 ,  140 ,  150  show differing widths of the housing  26  relative to the diffuser. Referring to  FIG. 10   a , an embodiment of the present invention  130  may have a housing  26 ″ that is substantially solid that receives the closed diffuser  25  on a top surface  326  that is narrower than the bottom  38  to which the diffuser  25  is attached, with the diffuser  25  having the LEDs  27  and circuit board assembly  29  mounted within. 
     Turning to  FIG. 10   b , an embodiment  140  may have a housing  26 ′″ that is substantially solid that receives the closed diffuser  25  on a top surface  328  that is wider than the bottom  38  to which the diffuser  25  is attached, with the diffuser  25  having the LEDs  27  and circuit board assembly  29  mounted within. 
     Referring now to  FIG. 10   c , an embodiment  150  may have a housing  26 ″″ that is substantially solid that receives the open diffuser  24  on a top surface  330  that is wider than the diffuser open side  39  to which the diffuser  24  is attached, with the diffuser  24  having the LEDs  27  and circuit board assembly  29  mounted within. 
     In yet another embodiment the housing  26  is substantially solid and has substantially the same width as the diffuser (not shown). 
     Turning now to  FIGS. 11   a  and  11   b , the open diffuser  24  of an embodiment of the present invention shown at  160 ,  170 , respectively, may surround a portion of the housing  26  such that the inner width  44  of diffuser  24  is substantially the same width as the upper portion of the housing, shown at  49 . In this embodiment, the diffuser  24  is in communication with the upper portion of the housing  49  which provides surfaces  51  to which the diffuser  24  and the LED mounting structure  29 , such as the circuit board assembly, can be attached. 
     Specifically referring to  FIG. 11   a , in the embodiment  160  the housing  26  has a raised topmost pedestal  69  that forms outer shoulders  62  with a width capable of receiving diffuser bottom edges  46  for securably attaching the diffuser  24  to housing  26 . 
     Turning to  FIG. 11   b , in yet another embodiment  170  the diffuser  24  is attached to the housing  26  through communication with diffuser inner surface  32  and housing outer surface  51  with no supporting shoulders  62  (as shown in  FIG. 11   a ). 
     Referring to  FIG. 12 , in another embodiment  180 , the diffuser  25  is securably attached to the LED mounting structure  29 , which, in turn, is attached to the housing  26  such that the diffuser  25  is not directly mounted to housing  26 . In this embodiment, the LED mounting structure, which may be the circuit board assembly, is sandwiched between the lower wall of the diffuser  25  and the upper surface of the housing  26 . 
     Referring now to  FIGS. 13   a - c , in other embodiments the LED mounting structure is integrated with or mounted directly to the diffuser. The diffuser  24 ,  25  may then be attached to housing, which also serves as a mounting structure for LEDs  27 , or the diffuser  24 ,  25  may be employed separately from any housing or other supporting or mounting structure. 
     Turning now to  FIG. 13   a , in this embodiment  190  the open diffuser  24  has bottom edges  46  that are securably attached to an integrated mounting structure/circuit board  47  to which the LEDs  27  are secured. An alternate embodiment  200  is shown in  FIG. 13   b , in which the closed diffuser  25  is securably attached to the mounting structure  47  to which the LEDs  27  are mounted such that the LEDs and mounting structure are enclosed within the interior of the diffuser  25 . 
     Referring to  FIG. 13   c , in another embodiment  210 , the LEDs  27  are partially within the interior  36  of the closed diffuser  25 , and the mounting structure  47  is securably attached to the bottom wall  38  of diffuser  25 . 
     Mounting structure  47  may be constructed from a relatively sturdy and durable material that is generally lightweight such as plastic, phenolic, cotton paper with epoxy, polyester, woven glass, or some combination of materials. In one embodiment, mounting structure  47  is a substantially opaque material. Mounting structure  47  may be constructed by a circuit board making process of the kind generally known in the art. 
     Referring to  FIG. 14   a , the position of the LEDs  27  and circuit board  29 , within a lighting arrangement with an open diffuser  24 , may be varied in different embodiments. In one embodiment  220  the LEDs  27  and circuit board  29  are substantially within the interior  37  of open diffuser  24 . In another embodiment  230  the LEDs  27  and circuit board  29  are within both a portion of the housing interior  56  and the diffuser interior  37 , and in yet another embodiment  240  the LEDs  27  and circuit board  29  are within the housing interior  56 . 
     Turning now to  FIG. 14   b , the position of the LEDs  27  and circuit board  29 , within a lighting arrangement with a closed diffuser  25 , may be varied in different embodiments. In one embodiment  250  the LEDs  27  and circuit board  29  are substantially within the interior  36  of closed diffuser  25 . In another embodiment  260  the LEDs  27  and circuit board  29  are within both a portion of the housing interior  56  and the diffuser interior  36 , and in yet another embodiment  270  the LEDs  27  and circuit board  29  are within the housing interior  56 . 
     LEDs  27  preferably emit light within at least one frequency of the human visible spectrum. In one embodiment, the LEDs  27  emit light within substantially a single frequency of visible light appearing to the human eye as a single color. In another embodiment, the LEDs  27  emit multiple frequencies of light either one frequency at a time or in combination such that it produces multiple visible colors. 
     Although the best mode contemplated by the inventors of carrying out the present invention is disclosed above, practice of the present invention is not limited thereto. It is further contemplated that various additions, modifications and rearrangements of the features of the present invention may be made without deviating from the spirit and scope of the underlying inventive concept.