Abstract:
A light-weight and energy-efficient lighting panel is constructed from a light-transmissive and light diffusive extrusion formed to have elongated hollows, which are hollow structures or volumes between two surfaces, at least one of which is transmissive and diffusive. Light projected into the hollow flows through the hollow and part of the light is emitted through the light transmissive and diffusive surfaces. Even though the light sources are located at the edges of a panel, the surface of the panel appears to be uniformly light by light sources distribute directly behind the panels rather than along the edges.

Description:
BACKGROUND 
       [0001]    Light emitting diodes are energy efficient and emit little thermal energy, but because they are small, they are ill-suited to provide meaningful illumination to large, open spaces commonly found in offices. A mechanism for collecting, diffusing and projecting light from several light emitting diodes would be advantageous over the prior art, if such a mechanism could also be manufactured inexpensively. An energy efficient lighting panel that can gather light from numerous diodes or other energy-efficient light sources, diffuse the light so that it does not seem to originate from LEDs or other point sources, and transmit the light would be an improvement over the prior art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  is a perspective view of a light panel; 
           [0003]      FIG. 2  is an exploded view of the light panel depicted in  FIG. 1 ; 
           [0004]      FIG. 3  is a perspective view of a first alternate embodiment of the light panel shown in  FIG. 1 ; 
           [0005]      FIG. 4  is an exploded view of another alternate embodiment of a light panel; 
           [0006]      FIG. 5  is a perspective view of another embodiment of a light panel; 
           [0007]      FIG. 6  is an exploded view of the structure shown in  FIG. 5 ; 
           [0008]      FIGS. 7-10  depict alternate embodiments of the web sections used to strengthen and provide hollows for an illumination panel; and 
           [0009]      FIGS. 11-14  show other embodiments of a light panel. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]      FIG. 1  is a perspective view of a light panel  100 . The light panel  100  is comprised of an illumination panel  102  having an upper surface  103 , which is both light transmissive and light diffusive. Light sources located along the edges of the panel project light inwardly, i.e., into the panel from the edges. The light sources emit a uniform level of light energy such that light transmitted through the panel&#39;s surface appears to originate from either a uniformly distributed light source behind the panel, or numerous individual light sources behind the panel, rather than light sources located along its edges and which project light into empty space beneath the upper surface  103 . 
         [0011]    As used herein, the term “transmissive” should be construed to mean that light is able to pass-through the panel. The term “diffusive” should be construed to mean tending to diffuse. Since “diffuse” means not concentrated or not localized, diffusive should be construed to mean tending to diffuse, de-localize or not concentrate. By way of example, an incoherent, i.e., non-laser, point light source located behind the upper surface  103  will thus appear to be larger and will tend to make the upper surface  103  appear as if it is entirely illuminated from its back side, which, not shown but within the body of the light panel  100 . 
         [0012]    The light panel  100  is also comprised of a back side  104 , not visible in  FIG. 1  because  FIG. 1  is a perspective view of the light panel  100 . The upper surface  103  and the back surface  104  are separated from each other by a separation distance  105 . The separation between the upper surface  103  and the back surface  104  is maintained by one or more internal web sections, not visible in  FIG. 1 . 
         [0013]    A left end cap  106  and a right end cap  107  enclose one or more elongated hollows, which as described below, extend between the left end cap and the right end cap and through which light from a light source travels. Since the light waves from light sources used with the panel  102  are incoherent, at least part of the light traveling through the hollows passes through the light transmissive and light diffusive upper surface  103 . 
         [0014]      FIG. 2  is an exploded view of the light panel  100  depicted in  FIG. 1 . The upper light transmissive and light diffusive surface  103  is planar. It is formed by extruding a plastic material thin enough to allow light to pass through it and to diffuse the light. The hollows are identified by reference numeral  202 . Vertical side walls identified by reference numeral  204 , are considered herein to be the aforementioned web sections  204 . The entire panel, including the top, bottom and side walls are preferably formed by one extrusion, all at once. 
         [0015]    The hollows  202  have first and second ends. The first end being proximate to the left end cap  106 , the second end being proximate to the right end cap  107 . As stated above, the hollows  202  are formed by a substantially vertical wall that forms the aforementioned web section  204 . Several web sections are shown in  FIG. 2 , each of which extends between the upper light transmissive surface  103  and the back surface  104 . Since the upper light transmissive and light diffusive surface  103  of panel  102 , the web sections  204  and the back surface or backside  104  are formed by extruding a plastic, all of them preferably have the same light transmissive and light diffusive properties allowing any of the surfaces to be used as light emitting. 
         [0016]    Two light strips  206  and  209  are comprised of integrated circuit boards, attached to which are light sources  208  such as light emitting diodes or incandescent bulbs. Electric energy is provided to the light sources  208  by connecting wires  205  and  207  to a power source. For brevity, light emitting diodes, incandescent bulbs or other light types are collectively referred to hereinafter as light sources, which are identified in  FIG. 2  by reference numeral  208 . 
         [0017]    The bodies of the light sources  208  project into the hollows  202  by a small distance. Since the light sources are mounted to a circuit board, the surface of which is held against the ends of the extruded panel  102 , and projects into the hollows, the light sources  208  are thus considered herein to be operatively coupled to the corresponding left end  210  and the right end  212  of the extrusion which forms the extruded light transmissive and light diffusive panel  102 . The light sources  208  direct light into the hollow and of course, along the back or reverse or interior side of the upper surface  103 . 
         [0018]    Light emitted from the light sources  208  will of course travel down the hollows  202 . Since the light is incoherent, at least part of the light passing through the hollow will also pass through the upper surface  103  because the upper surface is transmissive as well as diffusive. Inasmuch as the web structures  204  and the back surface  104  are also formed from the same plastic, the light from the light source  208  will also pass at least partly through those surfaces as well, unless the surfaces of those structures are coated with an opaque or reflective material. 
         [0019]    The back surface  104  of the extruded panel  102 , which is opposite the top surface  103 , has its own “upper surface”  203 , which is “inside” the hollow  202  or facing into the hollow  202 . In one embodiment, the top or interior surface  203  of the back surface  104  is coated with a polished aluminum or other reflective surface. Such a coating will tend to direct the incoherent light from the light sources  208  upwardly or out through the top or upper surface  103  of the light transmissive panel  102 . The back surface  104  could also be coated with a reflective material to provide a similar result. 
         [0020]      FIG. 3  is a perspective view of a first alternate embodiment of the light panel  100  shown in  FIG. 1 . In  FIG. 3 , the light panel  300  is comprised of an extruded plastic that is transmissive but not diffusive. An upper surface  303  is coated or overlaid with a light transmissive and light diffusive film  304 . In one embodiment, the film  304  passes all light wavelengths, in which case the entire upper surface  302  of the panel  300  will appear to emit white light when a white light passes through the hollows  305 . In another embodiment, the diffusive film  304  allows narrow bands or ranges of wavelengths to pass through, i.e., the film  304  appears to be colored or tinted. In such an embodiment, the entire panel  300  will thus appear to emit a uniform or substantially-uniform colored light. Color added to the film  304  can also be patterned or areas of the film colored differently and randomly. 
         [0021]      FIG. 4  is an exploded view of an alternate embodiment of the light panel  100  depicted in  FIG. 1 . A plastic that is at least partially light transmissive and light diffusive  402  is extruded to form the same illumination panel structure that is shown in  FIG. 1  but which is identified in  FIG. 4  by reference numeral  402 . 
         [0022]    A substantially planer upper surface  403  and a substantially planer lower surface  404  are separated from each other by substantially vertical web sections  405  that maintain the separation distance between the upper surface  403  and the lower surface  404 . The web sections in each embodiment also provide flexural rigidity to the panel  402 . Spacing between the web sections  405  is a design choice, however, those of ordinary skill will recognize that panel stiffness will be directly proportional to the number of web sections. The greater the number of web sections  405 , the stiffer the panel  402  will be, but at the expense of additional material and therefore cost to provide additional extruded web sections  405 . 
         [0023]    Unlike the light strips  206  and  209  shown in  FIG. 2 , the illumination panel  400  shown in  FIG. 4  is provided with two, substantially cylindrical, conventional fluorescent tubes  408  and  409 , which are also considered herein to be light sources. The light sources  408  and  409  are shown located outside or beyond the left end  406  of the panel  402  and the right end  410  of the panel  402 . The light sources  408  and  409  are thus considered to be outside of the hollows  407  formed by the aforementioned web sections  405 . End caps  411  and  412  are sized, shaped and arranged to frictionally engage the upper surface  403  and the opposing rear surface  404  the front wall  413  and an opposing back wall  414  to hold the light sources  410  up against the web sections  405  yet remain outside the hollows  407 . 
         [0024]      FIG. 5  is a perspective view of yet another embodiment of a light panel  100 .  FIG. 6  is an exploded view of the same structure. 
         [0025]    Referring now to  FIG. 6 , an extruded, transmissive and diffusive illumination panel  502  has a planar upper light transmissive and light diffusive surface  503  spaced apart and separated from a rear surface  504  by several web sections  602 . 
         [0026]    Two light strips  604  and  605  are each comprised of substantially U-shaped light pipes  606 . As used herein, “light pipe” should be construed to mean an optical fiber or a solid transparent plastic rod that transmits light lengthwise, i.e., along the length of the light pipe structure. In  FIG. 6 , the light pipes  606  are substantially U-shaped. Light sources  607  on light strips  604  and  605  direct light into the light pipes  606 , which conduct the light in a U-shaped material, into the hollows  603 . Light emitted from the externally-located light sources  607  is projected into a first or upper end  608  of the U-shaped light pipe  606 . At the lower end  609 , light leaves the light pipe and projects into the hollows  603  where at least part of the light travels through the hollow and at least part of that light passes through the light transmissive and light diffusive top surface  503 . The light sources  607  in  FIG. 6  are thus spatially separated from the hollows  603  yet transmit light through the light conduits embodied as the light pipes  606 . For purposes of claim construction, a light pipe  606  in combination with a light source  607  should also be considered to be a light source. 
         [0027]      FIGS. 7-10  depict alternate embodiments of the web sections used to “rigidize” or strengthen an extruded plastic, illumination panel. 
         [0028]      FIG. 7  depicts the web cross section shown in  FIG. 2 . The web sections  702  are uniformly spaced, vertical or substantially vertical, relative to the top surface  700  of the panel and the bottom surface  704  to form a single-layered illumination panel. 
         [0029]    In  FIG. 8 , an intermediate layer  804  is separated from a top layer  800  and a bottom layer  806  by web sections  802  that extend between both the top layer  800  and bottom layer  806 . 
         [0030]      FIG. 9  depicts a web section reminiscent of a honeycomb. Hexagonally-shaped hollows  900  are formed by extruding. The wall sections between the hexagonally-shaped hollows are sufficiently thin so that light sources in any one of the hexagonally-shaped hollows are able to transmit light through the most distant of the upper surface  902  and the lower surface  904 . 
         [0031]      FIG. 10  shows a random cross-sectional shape web the hollows  1000  of which are also randomly shaped. 
         [0032]      FIG. 11  shows yet another embodiment of a light panel  1100 . A substantially planar lower surface  1104  is separated by an upper curved surface  1102  by vertically-oriented web sections  1106 , the lengths of which change according to the desired curvature of the upper surface  1102 . The curved surface provided by the upper surface  1102  provides a more decorative and textured light source panel than do planar or substantially planar surfaces illustrated in  FIGS. 1-10  when the curved surface faces into a living space where it can be seen. 
         [0033]      FIG. 12  depicts yet another light transmissive panel  1200 . Two concentric light transmissive and light diffusive surfaces  1202  and  1204  have circular cross-sectional shapes. They are spaced apart from each other by several radially-oriented web sections  1206 , which define hollows  1208 . Each hollow  1208  thus forms a partial annulus and able to receive one or more of the light sources described above. 
         [0034]      FIGS. 13A and 13B  depict yet another embodiment of a light panel  1300 . In this figure, the light panel  1300  is substantially pie-shaped having an outer edge  1302  and an inner edge  1304  between which extend several vertically-oriented web sections  1306  which maintains the spacing between a light transmissive and light diffusive upper surface  1308  and an optionally light transmissive and light diffusive lower surface  1310 . The hollows  1312  are themselves pie-shaped sections defined by the radially-oriented web sections  1306 . Light sources can be placed into the pie-shaped hollows at either the outer edge  1302  or the inner edge  1304 . 
         [0035]    Finally,  FIG. 14A  depicts a perspective view of another embodiment of an illumination panel  1400 . The panel is comprised of a light transmissive and light diffusive upper surface  1402  and a light transmissive and light diffusive lower surface  1404 . As shown in  FIG. 14A , the surfaces  1402  and  1404  are separated from each other by a plurality of posts  1406  that extend between the two surfaces  1402  and  1404 . A hollow  1408  is embodied as the space between the panels and around the posts  1406 . As can be seen in  FIG. 14B , light sources such as those describe above, can be inserted into the hollow or fixed adjacent to its open edges projecting light into the hollow which will be reflected out of at least one of the surfaces  1402  and  1404 . 
         [0036]    It should be apparent to those of ordinary skill that the illumination panels can have opaque and transmissive sides that are either flat or curved. Light sources can be operatively coupled to hollows in illumination panels by being at least partially within a hollow, adjacent to or away from the hollow with emitted light conducted into the hollow by a light pipe. 
         [0037]    As used herein, the term “web” refers to regular or irregular shapes that maintain a space between surfaces that comprise an illumination panel but which also define a “hollow” through which light will pass lengthwise but also be emitted through a transmissive side of the panel. 
         [0038]    The illumination panel is preferably formed by extruding, however any method of manufacture can be used to construct the aforementioned light panel. A plastic for extruding should be selected that is both transmissive and diffusive, however, a clear or translucent plastic or acrylic can also be used with an overlaid diffusive layer. 
         [0039]    The foregoing description is for purposes of illustration. The true scope of the invention is set forth in the appurtenant claims.