US20090027920A1 - Light emitting panel assemblies - Google Patents

Abstract

Backlight assembly includes a waveguide having a greater width than height and at least one light emitting area for illuminating a display. A light source assembly optically coupled to the panel includes a light emitting source and at least a reflective or refractive surface to disperse light emitted from the light emitting source more along the width than height of the panel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a division of U.S. patent application Ser. No. 11/504,203, filed Aug. 15, 2006, which is a continuation of U.S. patent application Ser. No. 10/784,527, filed Feb. 23, 2004, now U.S. Pat. No. 7,160,015, dated Jan. 9, 2007, which is a division of U.S. patent application Ser. No. 09/256,275, filed Feb. 23, 1999, now U.S. Pat. No. 6,712,481, dated Mar. 30, 2004, which is a continuation-in-part of U.S. patent application Ser. No. 08/778,089, filed Jan. 2, 1997, now U.S. Pat. No. 6,079,838, dated Jun. 27, 2000, which is a division of U.S. patent application Ser. No. 08/495,176, filed Jun. 27, 1995, now U.S. Pat. No. 5,613,751, dated Mar. 25, 1997.
BACKGROUND OF THE INVENTION
• This invention relates generally, as indicated, to light emitting panel assemblies each including a transparent panel member for efficiently conducting light, and controlling the light conducted by the panel member to be emitted from one or more light output areas along the length thereof.
• Light emitting panel assemblies are generally known. However, the present invention relates to several different light emitting panel assembly configurations which provide for better control of the light output from the panel assemblies and for more efficient utilization of light, which results in greater light output from the panel assemblies.
SUMMARY OF THE INVENTION
• In accordance with one aspect of the invention, the light emitting panel assemblies include a light emitting panel member having a light transition area in which at least one light source is suitably mounted for transmission of light to the light input surface of the panel member.
• In accordance with another aspect of the invention, the light source is desirably embedded, potted or bonded to the light transition area to eliminate any air gaps, decrease surface reflections and/or eliminate any lens effect between the light source and light transition area, thereby reducing light loss and increasing the light output from the panel assembly.
• In accordance with another aspect of the invention, the panel assemblies may include reflective or refractive surfaces for changing the path of a portion of the light, emitted from the light source, that would not normally enter the panel members at an acceptable angle that allows the light to remain in the panel members for a longer period of time and/or increase the efficiency of the panel members.
• In accordance with another aspect of the invention, the light emitting panel members include a pattern of light extracting deformities or disruptions which provide a desired light output distribution from the panel members by changing the angle of refraction of a portion of the light from one or more light output areas of the panel members.
• In accordance with still another aspect of the invention, the light source may include multiple colored light sources for supplying light to one or more light output areas, and for providing a colored or white light output distribution.
• In accordance with yet another aspect of the invention, the panel assemblies include a transition area for mixing the multiple colored lights, prior to the light entering the panel members, in order to effect a desired colored or white light output distribution.
• The various light emitting panel assemblies of the present invention are very efficient panel assemblies that may be used to produce increased uniformity and higher light output from the panel members with lower power requirements, and allow the panel members to be made thinner and/or longer, and/or of various shapes and sizes.
• To the accomplishment of the foregoing and related ends, the invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but several of the various ways in which the principles of the invention may be employed.
BRIEF DESCRIPTION OF THE DRAWINGS
• In the annexed drawings:
• FIGS. 1 through 3 are schematic perspective views of three different forms of light emitting panel assemblies in accordance with this invention;
• FIG. 4ais an enlarged plan view of a portion of a light output area of a panel assembly showing one form of pattern of light extracting deformities on the light output area;
• FIGS. 4b, canddare enlarged schematic perspective views of a portion of a light output area of a panel assembly showing other forms of light extracting deformities formed in or on the light output area;
• FIG. 5 is an enlarged transverse section through the light emitting panel assembly ofFIG. 3 taken generally on the plane of the line5-5 thereof;
• FIG. 6 is a schematic perspective view of another form of light emitting panel assembly in accordance with this invention;
• FIG. 7 is a schematic top plan view of another form of light emitting panel assembly in accordance with this invention;
• FIG. 8 is a schematic perspective view of another form of light emitting panel assembly in accordance with this invention;
• FIG. 9 is a schematic top plan view of another form of light emitting panel assembly in accordance with this invention;
• FIG. 10 is a schematic top plan view of still another form of light emitting panel assembly in accordance with this invention;
• FIG. 11 is a side elevation view of the light emitting panel assembly ofFIG. 10;
• FIG. 11ais a fragmentary side elevation view showing a tapered or rounded end on the panel member in place of the prismatic surface shown inFIGS. 10 and 11;
• FIG. 12 is a schematic top plan view of another form of light emitting panel assembly in accordance with this invention;
• FIG. 13 is a schematic side elevation view of the light emitting panel assembly ofFIG. 12; and
• FIGS. 14 and 15 are schematic perspective views of still other forms of light emitting panel assemblies in accordance with this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Referring now in detail to the drawings, and initially toFIG. 1, there is schematically shown one form of light emitting panel assembly1 in accordance with this invention including a transparentlight emitting panel2 and one ormore light sources3 which emit light in a predetermined pattern in a light transition member orarea4 used to make the transition from thelight source3 to thelight emitting panel2, as well known in the art. The light that is transmitted by thelight transition area4 to the transparentlight emitting panel2 may be emitted along the entire length of the panel or from one or more light output areas along the length of the panel as desired to produce a desired light output distribution to fit a particular application.
• InFIG. 1 thelight transition area4 is shown as an integral extension of one end of thelight emitting panel2 and as being generally rectangular in shape. However, the light transition area may be of other shapes suitable for embedding, potting, bonding or otherwise mounting the light source. Also, reflective or refractive surfaces may be provided to increase efficiency. Moreover, thelight transition area4 may be a separate piece suitably attached to thelight input surface13 of the panel member if desired. Also, the sides of the light transition area may be curved to more efficiently reflect or refract a portion of the light emitted from the light source through the light emitting panel at an acceptable angle.
• FIG. 2 shows another form of lightemitting panel assembly5 in accordance with this invention including a panellight transition area6 at one end of thelight emitting panel7 withsides8,9 around and behind thelight source3 shaped to more efficiently reflect and/or refract and focus the light emitted from thelight source3 that impinges on these surfaces back through thelight transition area6 at an acceptable angle for entering thelight input surface18 at one end of thelight emitting panel7. Also, a suitable reflective material orcoating10 may be provided on the portions of the sides of the light transition areas of the panel assemblies ofFIGS. 1 and 2 on which a portion of the light impinges for maximizing the amount of light or otherwise changing the light that is reflected back through the light transition areas and into the light emitting panels.
• The panel assemblies shown inFIGS. 1 and 2 include asingle light source3, whereasFIG. 3 shows another light emitting panel assembly11 in accordance with this invention including twolight sources3. Of course, it will be appreciated that the panel assemblies of the present invention may be provided with any number of light sources as desired, depending on the particular application.
• The panel assembly11 ofFIG. 3 includes alight transition area12 at one end of thelight emitting panel14 having reflective and/orrefractive surfaces15 around and behind eachlight source3. Thesesurfaces15 may be appropriately shaped including for example curved, straight and/or faceted surfaces, and if desired, suitable reflective materials or coatings may be provided on portions of these surfaces to more efficiently reflect and/or refract and focus a portion of the light emitted for example from an incandescent light source which emits light in a 360° pattern through thelight transition areas12 into thelight input surface19 of thelight emitting panel14.
• Thelight sources3 may be mechanically held in any suitable manner in slots, cavities oropenings16 machined, molded or otherwise formed in the light transition areas of the panel assemblies. However, preferably thelight sources3 are embedded, potted or bonded in the light transition areas in order to eliminate any air gaps or air interface surfaces between the light sources and surrounding light transition areas, thereby reducing light loss and increasing the light output emitted by the light emitting panels. Such mounting of the light sources may be accomplished, for example, by bonding thelight sources3 in the slots, cavities oropenings16 in the light transition areas using a sufficient quantity of a suitable embedding, potting or bondingmaterial17. The slots, cavities oropenings16 may be on the top, bottom, sides or back of the light transition areas. Bonding can also be accomplished by a variety of methods that do not incorporate extra material, for example, thermal bonding, heat staking, ultrasonic or plastic welding or the like. Other methods of bonding include insert molding and casting around the light source(s).
• A transparent light emitting material of any suitable type, for example acrylic or polycarbonate, may be used for the light emitting panels. Also, the panels may be substantially flat, or curved, may be a single layer or multi-layers, and may have different thicknesses and shapes. Moreover, the panels may be flexible, or rigid, and may be made out of a variety of compounds. Further, the panels may be hollow, filled with liquid, air, or be solid, and may have holes or ridges in the panels.
• Eachlight source3 may also be of any suitable type including, for example, any of the types disclosed in U.S. Pat. Nos. 4,897,771 and 5,005,108, assigned to the same assignee as the present application, the entire disclosures of which are incorporated herein by reference. In particular, thelight sources3 may be an arc lamp, an incandescent bulb which also may be colored, filtered or painted, a lens end bulb, a line light, a halogen lamp, a light emitting diode (LED), a chip from an LED, a neon bulb, a fluorescent tube, a fiber optic light pipe transmitting from a remote source, a laser or laser diode, or any other suitable light source. Additionally, thelight sources3 may be a multiple colored LED, or a combination of multiple colored radiation sources in order to provide a desired colored or white light output distribution. For example, a plurality of colored lights such as LEDs of different colors (red, blue, green) or a single LED with multiple colored chips may be employed to create white light or any other colored light output distribution by varying the intensities of each individual colored light.
• A pattern of light extracting deformities or disruptions may be provided on one or both sides of the panel members or on one or more selected areas on one or both sides of the panel members, as desired.FIG. 4aschematically shows one suchlight surface area20 on which a pattern of light extracting deformities ordisruptions21 is provided. As used herein, the term deformities or disruptions are used interchangeably to mean any change in the shape or geometry of the panel surface and/or coating or surface treatment that causes a portion of the light to be emitted. The pattern of light extractingdeformities21 shown inFIG. 4aincludes a variable pattern which breaks up the light rays such that the internal angle of reflection of a portion of the light rays will be great enough to cause the light rays either to be emitted out of the panel through the side or sides on which the light extractingdeformities21 are provided or reflected back through the panel and emitted out the other side.
• These deformities ordisruptions21 can be produced in a variety of manners, for example, by providing a painted pattern, an etched pattern, a machined pattern, a printed pattern, a hot stamped pattern, or a molded pattern or the like on selected light output areas of the panel members. An ink or printed pattern may be applied for example by pad printing, silk screening, ink jet, heat transfer film process or the like. The deformities may also be printed on a sheet or film which is used to apply the deformities to the panel member. This sheet or film may become a permanent part of the light panel assembly for example by attaching or otherwise positioning the sheet or film against one or both sides of the panel member similar to the sheet orfilm27 shown inFIGS. 3 and 5 in order to produce a desired effect.
• By varying the density, opaqueness or translucence, shape, depth, color, area, index of refraction, or type ofdeformities21 on an area or areas of the panels, the light output of the panels can be controlled. The deformities or disruptions may be used to control the percent of light emitted from any area of the panels. For example, less and/orsmaller size deformities21 may be placed on panel areas where less light output is wanted. Conversely, a greater percentage of and/or larger deformities may be placed on areas of the panels where greater light output is desired.
• Varying the percentages and/or size of deformities in different areas of the panel is necessary in order to provide a uniform light output distribution. For example, the amount of light traveling through the panels will ordinarily be greater in areas closer to the light source than in other areas further removed from the light source. A pattern of light extractingdeformities21 may be used to adjust for the light variances within the panel members, for example, by providing a denser concentration of light extracting deformities with increased distance from thelight source3 thereby resulting in a more uniform light output distribution from the light emitting panels.
• Thedeformities21 may also be used to control the output ray angle distribution of the emitted light to suit a particular application. For example, if the panel assemblies are used to provide a liquid crystal display backlight, the light output will be more efficient if thedeformities21 cause the light rays to emit from the panels at predetermined ray angles such that they will pass through the liquid crystal display with low loss.
• Additionally, the pattern of light extracting deformities may be used to adjust for light output variances attributed to light extractions of the panel members. The pattern of light extractingdeformities21 may be printed on the light output areas utilizing a wide spectrum of paints, inks, coatings, epoxies, or the like, ranging from glossy to opaque or both, and may employ half-tone separation techniques to vary thedeformity21 coverage. Moreover, the pattern of light extractingdeformities21 may be multiple layers or vary in index of refraction.
• Print patterns of light extractingdeformities21 may vary in shapes such as dots, squares, diamonds, ellipses, stars, random shapes, and the like, and are desirably 0.006 square inch per deformity/element or less. Also, print patterns that are 60 lines per inch or finer are desirably employed, thus making the deformities or shapes21 in the print patterns nearly invisible to the human eye in a particular application thereby eliminating the detection of gradient or banding lines that are common to light extracting patterns utilizing larger elements. Additionally, the deformities may vary in shape and/or size along the length and/or width of the panel members. Also, a random placement pattern of the deformities may be utilized throughout the length and/or width of the panel members. The deformities may have shapes or a pattern with no specific angles to reduce moiré or other interference effects. Examples of methods to create these random patterns are printing a pattern of shapes using stochastic print pattern techniques, frequency modulated half tone patterns, or random dot half tones. Moreover, the deformities may be colored in order to effect color correction in the panel members. The color of the deformities may also vary throughout the panel members, for example to provide different colors for the same or different light output areas.
• In addition to or in lieu of the patterns of light extractingdeformities21 shown inFIG. 4a, other light extracting deformities including prismatic surfaces, depressions or raised surfaces of various shapes using more complex shapes in a mold pattern may be molded, etched, stamped, thermoformed, hot stamped or the like into or on one or more areas of the panel member.FIGS. 4band4cshow panel areas22 on whichprismatic surfaces23 ordepressions24 are formed in the panel areas, whereasFIG. 4dshows prismatic or other reflective orrefractive surfaces25 formed on the exterior of the panel area. The prismatic surfaces, depressions or raised surfaces will cause a portion of the light rays contacted thereby to be emitted from the panel member. Also, the angles of the prisms, depressions or other surfaces may be varied to direct the light in different directions to produce a desired light output distribution or effect. Moreover, the reflective or refractive surfaces may have shapes or a pattern with no specific angles to reduce moiré or other interference effects.
• As best seen in the cross sectional view ofFIG. 5, a back reflector (including trans reflectors)26 may be attached or positioned against one side of thepanel member14 ofFIG. 3 using asuitable adhesive28 or other method in order to improve light output efficiency of the panel assembly11 by reflecting the light emitted from that side back through the panel for emission through the opposite side. Additionally, a pattern of light extractingdeformities21,23,24 and/or25 may be provided on one or both sides of the panel member in order to change the path of the light so that the internal critical angle is exceeded and a portion of the light is emitted from one or both sides of the panel. Moreover, a transparent film, sheet orplate27 may be attached or positioned against the side or sides of the panel member from which light is emitted using asuitable adhesive28 or other method in order to produce a desired effect.
• Themember27 may be used to further improve the uniformity of the light output distribution. For example, themember27 may be a colored film, a diffuser, or a label or display, a portion of which may be a transparent overlay that may be colored and/or have text or an image thereon.
• If adhesive28 is used to adhere theback reflector26 and/orfilm27 to the panel, the adhesive is preferably applied only along the side edges of the panel, and if desired the end edge opposite thelight transition areas12, but not over the entire surface area or areas of the panel because of the difficulty in consistently applying a uniform coating of adhesive to the panel. Also, the adhesive changes the internal critical angle of the light in a less controllable manner than the air gaps30 (seeFIG. 5) which are formed between the respective panel surfaces and theback reflector26 and/orfilm27 when only adhered along the peripheral edges. Additionally, longer panel members are achievable whenair gaps30 are used. If adhesive were to be used over the entire surface, the pattern of deformities could be adjusted to account for the additional attenuation in the light caused by the adhesive.
• Referring further toFIG. 2, thepanel assembly5 shown therein also includes moldedposts31 at one or more corners of the panel7 (four such posts being shown) which may be used to facilitate mounting of the panel assembly and providing structural support for other parts or components, for example, a display panel such as a liquid crystal display panel as desired.
• FIG. 6 shows another form of light emittingpanel assembly32 in accordance with this invention including apanel member33, one or morelight sources3, and one or morelight output areas34. In addition, thepanel assembly32 includes atray35 having a cavity orrecess36 in which thepanel assembly32 is received. Thetray35 may act as a back reflector as well as end edge and/or side edge reflectors for thepanel33 and side and/orback reflectors37 for thelight sources3. Additionally, one or more secondary reflective orrefractive surfaces38 may be provided on thepanel member33 and/ortray35 to reflect a portion of the light around one or more corners or curves in a non-rectangular shapedpanel member33. These secondary reflective/refractive surfaces38 may be flat, angled, faceted or curved, and may be used to extract a portion of the light away from the panel member in a predetermined pattern.FIG. 6 also shows multiplelight output areas34 on the panel member that emit light from one or morelight sources3.
• FIG. 7 is a schematic illustration of still another form of light emittingpanel assembly40 in accordance with this invention including a panel member41 having one or morelight output areas42 and one or more light transition areas (mixing areas)43 containing a plurality oflight sources3 at one or both ends of the panel. Each transition area mixes the light from one or more light sources having different colors and/or intensities. In this particular embodiment, each of thelight sources3 desirably employs three colored LEDs (red, blue, green) in eachtransition mixing area43 so that the light from the three LEDs can be mixed to produce a desired light output color that will be emitted from thelight output area42. Alternatively, each light source may be a single LED having multiple colored chips bonded to the lead film. Also, two colored LEDs or a single LED having two colored chips may be used for a particular application. By varying the intensities of the individual respective LEDs, virtually any colored light output or white light distribution can be achieved.
• FIG. 8 shows yet another form of light emittingpanel assembly45 in accordance with this invention including a light emittingpanel member46 and alight source3 in alight transition area48 integral with one end of the panel member. In this particular embodiment, thepanel member46 is three-dimensionally curved, for example, such that light rays may be emitted in a manner that facilitates aesthetic design of a lighted display.
• FIG. 9 schematically shows another form of light emittingpanel assembly50 in accordance with this invention, including apanel member51 having multiplelight output areas52, and mounting posts and/or mountingtabs53. Thisparticular panel assembly50 may serve as a structural member to support other parts or components as by providing holes orcavities54,55 in thepanel member51 which allow for the insertion of modular components or other parts into the panel member. Moreover, a separate cavity orrecess56 may be provided in thepanel member51 for receipt of a correspondingly shapedlight transition area57 having one or morelight sources3 embedded, bonded, cast, insert molded, epoxied, or otherwise mounted or positioned therein and a curved reflective orrefractive surface58 on thetransition area57 and/or wall of the cavity orrecess56 to redirect a portion of the light in a predetermined manner. In this way thelight transition area57 and/or panel member may be in the form of a separate insert which facilitates the easy placement of the light source in a modular manner. Areflector58 may be placed on the reflective or refractive surface of the cavity orrecess56 orinsert57. Where thereflector58 is placed on the reflective or refractive surface of the cavity orrecess56, the cavity or recess may act as a mold permitting transparent material from which thetransition area57 is made to be cast around one or morelight sources3.
• FIGS. 10 and 11 schematically show another form of light emittingpanel assembly60 in accordance with this invention including apanel member61 having one or morelight output areas62. In this particular embodiment, an off-axislight transition area63 is provided that is thicker in cross section than the panel member to permit use of one or morelight sources3 embedded or otherwise mounted in the light transition area that are dimensionally thicker than the panel member. Also, a three-dimensional reflective surface64 (FIG. 11) may be provided on thetransition area63. Moreover, a prism65 (FIG. 11) or tapered, rounded, or otherwise shaped end66 (FIG. 11a) may be provided at the end of the panel opposite thelight sources3 to perform the function of an end reflector. Thelight sources3 may be oriented at different angles relative to each other and offset to facilitate better mixing of the light rays67 in thetransition area63 as schematically shown inFIG. 10 and/or to permit a shorterlength transition area63 to be used.
• FIGS. 12 and 13 schematically show still another form of light emittingpanel assembly70 in accordance with this invention which includes one or morelight transition areas71 at one or both ends of thepanel member72 each containing a singlelight source73. The transition area orareas71 shown inFIGS. 12 and 13 collect light with multiple or three-dimensional surfaces and/or collect light in more than one plane. For example eachtransition area71 shown inFIGS. 12 and 13 has elliptical and parabolic shape surfaces74 and75 in different planes for directing the light rays76 into the panel member at a desired angle.
• Providing one or more transition areas at one or both ends of the panel member of any desired dimension to accommodate one or more light sources, with reflective and/or refractive surfaces on the transition areas for redirecting the light rays into the panel member at relatively low angles allows the light emitting panel member to be made much longer and thinner than would otherwise be possible. For example the panel members of the present invention may be made very thin, i.e., 0.125 inch thick or less.
• FIG. 14 schematically illustrates still another form of light emittingpanel assembly80 in accordance with this invention including alight emitting panel81 and one or morelight sources3 positioned, embedded, potted, bonded or otherwise mounted in alight transition area82 that is at an angle relative to thepanel member81 to permit more efficient use of space. An angled or curved reflective orrefractive surface83 is provided at the junction of thepanel member81 with thetransition area82 in order to reflect/refract light from thelight source3 into the body of thepanel member81 for emission of light from one or morelight emitting areas84 along the length of the panel member.
• FIG. 15 schematically illustrates still another form of light emittingpanel assembly90 in accordance with this invention including alight transition area91 at one or both ends of a light emittingpanel member92 containing aslot93 for sliding receipt of an LED or other suitablelight source3. Preferably theslot93 extends into thetransition area91 from theback edge94, whereby thelight source3 may be slid and/or snapped in place in the slot from the back, thus allowing the transition area to be made shorter and/or thinner. Thelight source3 may be provided with wings, tabs orother surfaces95 for engagement in correspondingly shaped recesses orgrooves96 or the like in thetransition area91 for locating and, if desired, securing the light source in place. Also, thelight source3 may be embedded, potted, bonded or otherwise secured within theslot93 in thelight transition area91 of thepanel member92. Light from a secondarylight source97 may be projected through thepanel member92 for indication or some other effect.
• The various light emitting panel assemblies disclosed herein may be used for a great many different applications including for example LCD back lighting or lighting in general, decorative and display lighting, automotive lighting, dental lighting, phototherapy or other medical lighting, membrane switch lighting, and sporting goods and apparel lighting or the like. Also the panel assemblies may be made such that the panel members and deformities are transparent without a back reflector. This allows the panel assemblies to be used for example to front light an LCD or other display such that the display is viewed through the transparent panel members.
• Although the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the claims.

Claims (13)

1. A backlight assembly comprising a waveguide panel having a greater width than height, and having at least one light emitting area for illuminating a display, at least one light source assembly optically coupled to the panel, wherein the light source assembly comprises a light emitting source and at least a reflective surface or a refractive surface to disperse light emitted from the light emitting source more along the width than the height of the panel.

2. The assembly ofclaim 1 wherein the surface is a curved refractive surface.

3. The assembly ofclaim 2 wherein the curved refractive surface curves around an axis perpendicular to the width of the panel to define a cylindrical surface.

4. The assembly ofclaim 3 wherein the refractive surface is integral to the light emitting source.

5. The assembly ofclaim 4 wherein the panel defines a cavity, slot or recess to receive the light source assembly.

6. The assembly ofclaim 1 wherein the surface is a refractive surface that is around or behind the light emitting source.

7. The assembly ofclaim 6 wherein the refractive surface is curved, straight or faceted.

8. The assembly ofclaim 7 wherein a transition area is between the light source assembly and the light emitting area.

9. The assembly ofclaim 8 wherein the panel defines a slot, cavity or recess to receive the light source assembly.

10. The assembly ofclaim 1 wherein the reflective surface or the refractive surface is defined in the panel.

11. The assembly ofclaim 1 further comprising a tray, frame or substrate to hold the light emitting source, wherein the surface is a refractive surface that is defined in the tray, frame or substrate.

12. The assembly ofclaim 11 wherein the tray, frame or substrate defines a slot, cavity or recess to receive the light source assembly.

13. The assembly ofclaim 11 wherein the tray, frame or substrate has at least one of a back reflector, an end edge reflector, or a side edge reflector for the panel, or at least one of a side reflector or a back reflector for the light source.

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