Panel backlighting systems

Abstract

In a backlighting system for a panel, a light-guide plate is installed along a reverse side of the panel. A light source is associated with, and removably optically coupled to, the light-guide plate so that it emits light into an edge of the light-guide plate. The light source may, e.g., be installed under a depending skirt or lip of the panel. The light source may be a direct or an indirect emitter and may have the characteristics of a light guide itself. In some embodiments, the reflector and a backing plate may be secured to a light-guide plate by fasteners driven through a thickness of the light-guide plate. The light-guide plate may have pre-formed holes, at least some of which are in a light-emitting area of the light-guide plate, to receive the fasteners.

Description

PANEL BACKLIGHTING SYSTEMSTECHNICAL FIELD

[0001] Embodiments of the invention relate to panel backlighting systems.BACKGROUND

[0002] As solid-state lighting based on light-emitting diodes (LEDs) has come to the fore, it has become popular not only as a replacement for existing light sources, but as a novel source of general, task, and accent lighting. Because of its small size and variety of configurations, solid-state lighting can be placed where traditional incandescent and fluorescent light sources cannot.

[0003] Recently, there has been a surge in the use of LED lighting to backlight countertops, wall panels, and other such surfaces. In a typical application, strips of LED linear lighting, or light-guide panels (LGPs) that use strips of LEDs, are installed under or behind a translucent countertop or panel. The countertop or panel may be frosted or recycled glass, honey onyx, quartzite, or quartz, to name a few options.

[0004] As one example, U.S. Patent No. 11,555,609 discloses a system for backlighting a panel, such as a countertop. In this system, specially-adapted LGPs are installed under the translucent countertop. The LGPs use enclosed strips of LED linear lighting as light sources. While the system disclosed by this patent is effective for its purpose, designs like this have a problem that has hindered market acceptance: the LED light sources are difficult or impossible to replace in the field. This means that if the LED linear lighting fails, the countertop and cabinetry may need to be fully disassembled and rebuilt to replace the failed strip. Moreover, failure over the functional lifetime of a countertop is a distinct possibility: although LEDs may have a longer operating lifetime than traditional incandescent and fluorescent light sources under at least some conditions, it is unreasonable to assume that LEDs installed under a countertop or panel will never fail.BRIEF SUMMARY

[0005] One aspect of the invention relates to a backlighting system for a panel, and another aspect of the invention relates to a backlit panel.

[0006] A backlighting system according to one aspect of the invention includes a light-guide plate with a main emitting surface and a reverse surface. The main emitting surface has emitting structure. A reflector is installed on the reverse surface of the light guide. A light source is associated with and removably optically coupled to the light-guide plate, such that light from the light source is emitted into an edge of the light-guide plate.

[0007] In backlit panel according to an aspect of the invention, the panel may have a depending lip, and the light source may be removably secured under the lip, directly adjacent to the light guide. For example, the light source may be wedged in place between an inner surface of the depending lip and the light-guide plate, or it may be secured by tape, a bead of caulk, or other such materials. The light-guide plate and reflector may be secured to the reverse side of the panel, e.g., by adhesive bonding, in at least some embodiments.

[0008] Another aspect of the invention relates to a light-guide plate assembly. The light-guide plate assembly has a light-guide plate, a reflector, a backing panel, and a plurality of fasteners. The plurality of fasteners extend through the light guide panel to secure the light-guide plate and the reflector to the backing panel. In some cases, at least some of the plurality of fasteners may extend through a lightemitting area of the light-guide plate. In some cases, the light-guide plate may include a pattern of pre-formed holes across the surface thereof. Each of the pattern of preformed holes is sized and adapted to receive one of the plurality of fasteners. In some cases, a light-guide plate as described above may have a non-uniform light-releasing pattern on its surface. For example, a non-uniform light-releasing pattern may use a continuous or banded gradient that places less light-releasing structure close to a light source and more light-releasing structure farther from the light source.

[0009] Yet another aspect of the invention relates to a light source for the kinds of backlighting systems and backlit panels described above. The light source may have a translucent body that serves as a light guide with at least one emitting surface, and a second light-emitting element directly optically coupled to the body toemit second light into the body. In some embodiments, a first extrusion may cover a bottom surface of the body, enclose the second light-emitting element, and optically couple the second light-emitting element to the body. In those embodiments, a second extrusion may cover the top of the body and mount the first light-emitting element. A horizontally-extending flange on the second extrusion may help to isolate the first lightemitting element and ensure that its light is directed into a light-guide plate.

[0010] Other aspects, features, and advantages of the invention will be set forth in the following description.BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0011] The invention will be described with respect to the following drawing figures, in which like numerals represent like features throughout the description, and in which:

[0012] FIG. 1 is a partially cut-away perspective view of a cabinet with a countertop that includes a backlighting system according to an embodiment of the invention;

[0013] FIG. 2 is an exploded view of the cabinet and countertop of FIG. 1;

[0014] FIG. 3 is a cross-sectional view taken through Line 3-3 of FIG. 1;

[0015] FIG. 4 is a cross-sectional view similar to the view of FIG. 3, illustrating an alternative way of securing a lighting source in place;

[0016] FIG. 5 is a perspective view of the light source of FIG. 4 in isolation;

[0017] FIG. 6 is a cross-sectional view similar to the view of FIG. 3, illustrating a backlighting system with a light source according to another embodiment of the invention;

[0018] FIG. 7 is a cross-sectional view illustrating the placement of a backlighting system at a comer intersection between two panels;

[0019] FIG. 8 is a top plan view of a light-guide plate according to another embodiment of the invention;

[0020] FIG. 9 is a sectional view of the light-guide plate, taken through Line 9-9 of FIG. 8;

[0021] FIG. 10 is a top plan view of a light-guide plate according to another embodiment of the invention;

[0022] FIG. 11 is a side-elevational view of the light-guide plate of FIG.10;

[0023] FIG. 12 is a top plan view of a light-guide plate with a variabledensity light-releasing pattern according to yet another embodiment of the invention;

[0024] FIG. 13 is a cross-sectional view similar to the view of FIG. 3, illustrating the use of a light-guide plate according to FIGS. 8-12 with a light-emitting element according to another embodiment of the invention; and

[0025] FIG. 14 is a cross-sectional view similar to the view of FIG. 13, illustrating the use of a light source with a custom extrusion.DETAILED DESCRIPTION

[0026] FIG. 1 is a partially cut-away perspective view of a backlighting system, generally indicated at 10, according to one embodiment of the invention. The backlighting system 10 is shown installed on a cabinet 12. Using system 10, diffused light is produced and transmitted through a countertop 14. The countertop 14 itself is at least partially light-transmissive and is thus backlit by system 10. This may provide ambient or task lighting to someone working on the countertop 14, or it may simply be used as accent lighting, or for ambience.

[0027] The cabinet 12 shown is of the type that might be found, e.g., in a residential kitchen or bathroom. However, as those of skill in the art will understand, the invention need not be limited to residential and commercial kitchens and bathrooms, backlighting systems like system 10 may be installed, e.g., as laboratory workbench surfaces, light tables, drafting tables, or any other, similar work surfaces that would benefit from being backlit. Thus, the term “countertop” should be read broadly to include a wide range of work surfaces and decorative surfaces. In the kitchen or bathroom environment, the countertop 14 will often be a material such as onyx, quartz, or agate, but there are many other possibilities. For example, the countertop 14 could be made of a glass slab, such as a borosilicate glass slab, and may be etched, sandblasted, pigmented, etc., to at least partially hide the components below. In environments in which wear and environmental resistance are not important considerations, the countertop 14 could be made of poly(m ethyl methacrylate) (PMMA) or polycarbonate, to name but a few materials. Other possibilities for thecountertop 14 include two-part resins, such as epoxies, that are poured into a mold. For example, the countertop 14 may be comprised of a resin with various colorants included therein, or it may be comprised of a combination of a resin and other materials, such as wood, with or without dyes or colorants.

[0028] Above, the term “at least partially light-transmissive” is used with the understanding that, if the luminous flux is great enough, almost any material is at least partially light-transmissive. The limitations in the material of the countertop 14 are thus more practical and situational than anything else - at some point, backlighting a more-opaque material will require so much light and generate so much heat that it will be undesirable. However, materials such as marble are not necessarily excluded as materials for the countertop 14.

[0029] The configuration of the cabinet 12 is not critical, and in at least some embodiments, there need be no cabinet 12; rather, only some kind of support base is needed. If there is no need for an internal storage volume, the support base may comprise nothing more than, e.g., a set of legs or a pedestal. The cabinet 12 has internal storage space with cabinet doors 16 and drawers 18 provided to access the internal space. In this embodiment, the cabinet 12 is rectangular in top plan view, although it may be L-shaped in top plan view or have any other shape.

[0030] The use of such a system 10 with a cabinet 12 is only one possible example. As will be described in more detail below, the system 10 could be implemented as a backlighting system for a wall panel or panels. Thus, this description will use the term “panel” as a general term to encompass wall panels, countertops, and other types of decorative and functional surfaces that may be backlit with a system 10 according to an embodiment of the present invention, and the countertop 14 may thus also be referred to interchangeably as a panel 14. Note that a “panel,” as that term is used here, need not be flat - e.g., the countertop 14 has a depending skirt or lip 20 20 in all sides. In fact, for reasons that will be explained in more detail below, it is helpful in this embodiment if the panel has some sort of lip covering its sides. A panel 14 may be wall-mounted, in which case the support structure described above may also be, e.g., a support bracket that attaches to a wall.

[0031] In the view of FIG. 1, one comer of the countertop 14 is partially cut away to reveal the components of the backlighting system 10, including a light-guide plate 34 and light sources 40, 42 that are arranged beneath the countertop 14 to provideeven backlight to it. FIG. 2 is an exploded perspective view, illustrating the components of the backlighting system 10 and their arrangement in more detail. More specifically, overtop of the cabinet 12 lies an overlayment 30 that provides structural support for system 10 as well as the countertop 14 itself. The overlayment 30 may be a sheet of wood, plywood, particle board, sheet metal, etc. As those of skill in the art will realize, however, the overlayment 30 is an optional component, used if, in the particular application or installation, the other components of system 10 and the countertop 14 will not have sufficient structural support otherwise. In some applications and installations, the other components may be supported directly by the cabinet 12. In a general panel installation, like a wall panel installation, the overlayment 30 (which could also be referred to as an underlayment 30 in a general panel installation) may serve as a means of attaching the components of system 10 and the panel 14 itself to the wall or other substrate. In practice, the overlayment / underlayment 30 may be adhered, nailed, bolted, or secured in some other conventional fashion to the substrate.

[0032] Atop the overlayment 30 is placed a reflective sheet 32. The reflective sheet 32 is a thin sheet of material that reflects light directed away from the countertop or panel 14 back toward the countertop or panel 14. The reflective sheet 32 may be a sheet of white plastic or laminated paper, it may be a reflective metal foil, or it may be a metallicized sheet of plastic, such as a metallicized sheet of biaxially- oriented polyethylene terephthalate (BoPET; MYLAR®).

[0033] Overtop of the reflective sheet 32, a light-guide plate 34 is installed. The light-guide plate 34 generally matches the size and shape of the reflective sheet 32 beneath it and may be made of any material with a higher refractive index than the medium in which the light-guide plate 34 sits. In the overwhelming majority of applications and installations, the light-guide plate 34 will be installed in room air; therefore, any material with an index of refraction higher than that of air may be used. Sheets of plastics, such as PMMA, polycarbonate, and poly(vinyl chloride) (PVC) are particularly suitable, although various types of glass may also be used. On the upper or outer broad surface 36 of the light-guide plate 34, a surface pattern 38 is etched, formed by laser inscribing, or formed by some other process. The surface pattern 38 is, in effect, a pattern of defects that causes light to be released from the light-guide plate 34 along the surface 36.

[0034] In this description, the term “light-guide plate 34” is used in the singular. However, multiple light-guide plates 34 may be used. For example, two plates could be set immediately adjacent to one another to cover a larger area, or an area of irregular shape could be covered by multiple light-guide plates of different shapes and sizes. If multiple light-guide plates are used, they should be placed adjacent to one another closely enough so that they are optically coupled together to act as a single light guide.

[0035] As shown in FIG. 2, the countertop or panel 14 may lie directly over the light-guide plate 34. However, there are installations in which small spacers may be used between the two. For example, if the material of the countertop or panel 14 has an index of refraction similar to that of the light-guide plate 34, such that direct contact between the two would alter the performance of the light-guide plate 34 and release light in a grossly uneven way, small spacers may be used to introduce a gap between the two components 16, 34.

[0036] As those of skill in the art will note, the light-guide plate 34 is not a light guide panel. A “light guide panel,” as that term is traditionally used, is a device that includes both a light guide and a light source. By contrast, the light-guide plate 34 does not include a light source. The light sources 40, 42 are separate elements whose position(s) and securement will be explained in greater detail below.

[0037] In many embodiments, the light-guide plate 34 and reflective sheet 32 may be adhesively bonded or otherwise permanently secured to the underside of the panel or countertop 14 to make those components one integrated whole. How this is done will vary from embodiment to embodiment, depending on the nature of the panel or countertop 14 and other situation-specific factors. In many cases, adhesives may be the most convenient way of securement, although fasteners may be used in some embodiments. If the components 32, 34, 14 are bonded or otherwise secured together, it may make an underlayment or overlayment 20 unnecessary.

[0038] Bonding methods will depend on the surface roughness of the underside or reverse side of the panel or countertop 14 and other factors. Generally speaking, any adhesive that is used between the panel or countertop 14 and the lightguide plate 34 should not disrupt the light emission from the light-guide plate 34. Bonding the reflective sheet 32 to the light-guide plate 34 may be somewhat simpler. For example, a light coating of a spray adhesive could be applied to both surfaces, andthe light-guide plate 34 could then be laminated or pressed with the reflective sheet 32 until the adhesive is cured.

[0039] FIG. 3 is a cross-sectional view taken through Line 3-3 of FIG. 1, illustrating the components of the backlighting system 10 in an installed configuration under the countertop or panel 14. In addition to illustrating the components 30, 32, 34, 14 in their final, installed locations, FIG. 3 shows a light source 40 in more detail.

[0040] Light guide panels (LGPs) were used in the system of U.S. Patent No. 11,555,609 because LGPs, with their light-blocking frames, ensure that all or nearly all of the light emitted by an LED light source enters a light-guide plate and is subsequently emitted along the desired plane. This maximizes evenly-diffused light and avoids undesirable light leaks and the resulting bright spots. However, the present inventors have found that in panel backlighting applications like the one described here, light leaks may be less of a concern, because the countertop or panel 14 is usually thick enough and / or opaque enough to hide small light leaks. Thus, while the light sources 40, 42 in system 10 are placed so as to be associated with and optically coupled to the light-guide plate 34 into which they emit light, the coupling between the two elements is looser and need not be entirely light-occlusive, as an LGP frame would be. Put in other words, the light sources 40, 42 are only indirectly coupled to the light-guide plate 34 such that they emit light into the edge of the light-guide plate 34; they are not physically connected to the light-guide plate 34 in the illustrated embodiment, e.g., by a frame.

[0041] In most panel or countertop 14 installations, there is a gap between the outer edge of the cabinet 12 and the inner edge of the skirt or lip 20 20 of the countertop or panel 14. This gap is indicated as gap G in FIG. 3. The gap G is created by making the countertop or panel 14 slightly larger than its substrate on at least one side. The light source 40 is inserted into the gap G, aligned so that light-emitting elements 44, 50, which would typically be strips of LED linear lighting, emit directly into the side edge 46 of the light-guide plate 34. Thus, the light sources 40, 42 and the light-guide plate 34 work together as a kind of “deconstructed,” frameless LGP. Depending on the embodiment, the luminous flux needed for illumination, the presence of gaps G, and other factors, light sources 40, 42 may be included on only one side, on several sides, or on all sides. For this reason, the light source 42 is shown in phantomin FIG. 1. Any light source 40, 42 may have any number of light-emitting elements 44, 50, for reasons that will be described below in more detail.

[0042] As those of skill in the art will appreciate, although the cabinet 12 and its countertop 14 are shown as rectangular, panels according to embodiments of the invention may be polygons of different shapes, they may have all curved sides, or they may have some combination of straight and curved sides. On any given side, there may be any number of individual light sources 40, 42, or a single light source 40, 42 may cover the entire side. Depending on its nature, a light source 40, 42 may be straight or curved in its extent, as will be described below in more detail.

[0043] Preferably, the light sources 40, 42 are mounted in the gap G in such a way that they are at least relatively easily removed for repair, replacement, and upgrade. In FIG. 3, a wedge or wedges 48 is inserted into the gap G along the bottom, between the inner edge of the skirt or lip 20 and the light source 40, fixing the light source 40 in position. To remove the light sources 40, 42, one would simply remove the wedges.

[0044] FIG. 4 illustrates a cross-section that is the same as FIG. 3, except that, as shown in FIG. 4, light-occlusive tape 49 is used along the bottom of the gap G to fix the light sources 40, 42 in place. In other embodiments, the light source 40 could be fixed in place by a bead of caulking material, which can be sliced through or otherwise removed to remove the light source 40. Multiple methods of securement could also be used. For example, a light source 40, 42 could be shimmed or wedged in place, and then the gap G could be taped or caulked shut.

[0045] As those of skill in the art will appreciate, the method by which the light sources 40, 42 are secured in place will depend, at least in part, on the size of the gap G. The options described above assume that the gap G is small. Particularly if the gap G is larger, many other means of securement are possible. For example, the light sources 40, 42 may be mounted on small, horizontal shelves that are secured to the bottom of the skirt or lip 20; the light sources 40, 42 may be secured to the inside of the skirt or lip 20 by screws or bolts inserted horizontally into the rear (i.e., hidden) surface of the skirt or lip 20; or the light sources 40, 42 may be secured to a horizontal shelf that is cantilevered to extend inwardly from the rear of the skirt or lip 20.

[0046] The nature of the light sources 40, 42 may vary considerably from embodiment to embodiment and installation to installation. FIG. 5 is a perspectiveview illustrating the light source 40 shown in FIGS. 3 and 4 in isolation. The light source 40 includes a body 60 made of a light-transmissive material, like PMMA, poly(vinyl chloride) (PVC), or polycarbonate. The body 60 in this case has rectilinear cut outs 62, 64 on opposite exterior edges, giving the body 60 a stair-step or zig-zag appearance. Each of the cut outs 62, 64 houses one of the light-emitting elements 44, 50. The upper light-emitting element 44, which emits into the light-guide plate 34 when the light source 40 is installed, is mounted on the vertical sidewall 66 formed by the upper cut out 62, and emits to the side; the lower light-emitting element 50 is placed on a horizontal shelf 68 formed by the cut out 64, and emits upwardly, into the body 60. (Here, the cut outs 62, 64 are slightly different: the cut out 62 removes a full corner of the body 60; the lower cut out 62 cuts into the side of the body 60 without removing the entire comer, leaving a shelf 68 to support the light-emitting element 50.)

[0047] In general, a light source used in embodiments of the invention may be a direct emitter of light, as in a strip of LED linear lighting, it may be an indirect emitter, like an LGP, or it may have attributes of both. As shown in FIGS. 3-5, the light source 40 has direct- and indirect-emitting elements. More specifically, the element 44 that emits light into the light-guide plate 34 does so directly. However, the other element 50 emits light into the body 60.

[0048] If a light source 40 is an indirect emitter with a light guide, the location where light is released may vary from embodiment to embodiment and application to application, depending on where light is needed. The present inventors have found that if a light-emitting element emits directly up into the countertop or panel 14, that may create a “halo” around the edges of the countertop or panel 14. To avoid this, the light source 40 has a light-releasing defect pattern 68 on the side 70, releasing most of the light within the body 60 in the direction of the skirt or lip 20 20 when the light source 40 is installed. The upper surface 72 of the body 60 opposite the lightemitting element 50 is protected by light-occlusive or reflective material 74, such as light-blocking tape, to prevent direct upward emission of light. Similarly, the side 76 of the body 60 opposite the emitting surface 70 has a reflective sheet 78 adhered to it to prevent emission along that surface. In general, these reflective materials and sheets 74, 78 may extend over as much of the body 60 as necessary in order to ensure that light is emitted only where desired.

[0049] In FIGS. 3-5, the body 60 of the light source 40 is shown as a single piece. As shown, it may be molded, cast, or machined from a larger block of material. However, in other embodiments, the body 60 may be made from multiple pieces, e.g., two strips of PMMA or polycarbonate that are adhered or solvent bonded together.

[0050] FIG. 6 is a cross-section similar to the view of FIG. 3, illustrating a light source according to another embodiment of the invention, generally indicated at 100. The light source 100 in this case comprises a simple strip of LED linear lighting 102, installed on a thin substrate 104. The substrate 104 may be, e.g., a metal or plastic strip, e.g., made of aluminum, steel, polyethylene terephthalate (PET), PMMA, polycarbonate, etc. and is intended to add some measure of structural reinforcement to the strip of LED linear lighting 102. The LED linear lighting 102 is positioned to emit light directly into the side of the light-guide plate 34. The gap G is sealed with a lightocclusive tape, strip, or sealant 106.

[0051] The use of a light source or sources with multiple emitters may be useful in certain other situations as well, particularly if two panels meet at a comer and it is desirable to backlight both of them. FIG. 7 is a cross-sectional view of a portion of a panel 150 that includes a corner 152. In FIG. 7, the panel 150 is shown as a single panel, but it could be two panels that meet at a corner. Each portion of the panel 150 is backed by a separate light-guide plate 154, 156, which, in turn, is backed by an underlayment or substrate 158, 160. The underlayment or substrate 158, 160 may be wood, metal, or any other suitable material, and as was described above, the underlayment or substrate 158, 160 may be optional in at least some embodiments, particularly if the light-guide plates 158, 160 are bonded or otherwise integrated with the panel 150. As in the system 10 described above, a reflective sheet 162, 164 may be used directly behind or under the light-guide plates 154, 156.

[0052] To provide light, a single light source 166 includes a substrate 167, rectilinear in this embodiment, with two separate light-emitting elements 168, 170, each element 168, 170 arranged to emit light directly into one of the light-guide plates 154, 156. The light-guide plates 154, 156 would be arranged to emit that light into the panel 150 to backlight the panel. In some embodiments, the light source 166 may have additional light-emitting elements arranged to emit light in other directions so as to avoid a dark corner.

[0053] In general, embodiments of the invention provide a way to backlight countertops and panels 14 while allowing the light sources 40, 42, 100, 166 to be removable and replaceable. The groove or gap G may be small. For example, if the light source is a simple strip of LED linear lighting, as is the light source 100, the gap G may be, e.g., about 4mm wide and 8mm in height. If the light source is an indirect emitter with a light guide, like the light sources 40, 42, the gap may need to be slightly taller and, in some cases, slightly wider. Gaps like this are common in many installations. Additionally, in a countertop installation, embodiments of the present invention generally do not require the countertop to be raised very much. Typically, the added height created by the light-guide plate 34 and its reflective sheet 32 is less than one centimeter, and often only a few millimeters, as compared with several centimeters for the system disclosed in U.S. Patent No. 11,555,609.

[0054] The focus of the above description is on providing backlight to countertops and panels 14. For backlighting applications, a single surface 36 of the light-guide plate 34 is adapted to emit light, usually by including some light-releasing pattern 38. In some cases, embodiments of the invention may emit light in other directions as well. For example, a light-guide plate may have light-releasing structure, like a surface pattern 38, on both sides, including both the side facing the countertop or panel 14 and the reverse side. If that bidirectionally-emitting light-guide plate is installed in a countertop or tabletop backlighting application, it would, in essence, provide downlight as well as backlight for the countertop or panel 14. In a wall-panel application, such a light-guide plate might provide wall-washing or accent light around the panel, as well as backlighting for the panel. In these kinds of applications, the lightguide plate would typically be installed without an opaque underlayment 30, so that the light can escape.

[0055] In the description above, the reflective sheet 32 is placed under the light-guide plate 34 and adhesives are described as one option for securing the two together. The present inventors have found that because the refractive index of most polymer adhesives is relatively close to the refractive index of most materials used to construct a light-guide plate 34, adhesives applied to the light-guide plate 34 may cause light leaks. The degree to which this is a problem will depend on the details of the particular embodiment or implementation. However, to avoid the issue, mechanicalsecurement of the two elements 32, 34 may be more advantageous, at least in some embodiments.

[0056] In U.S. Patent No. 11,555,609, the light-guide plate is interrupted by short, hollow posts of the same material as the light-guide plate. With this arrangement, effort is made to ensure that any fasteners do not interfere with light conduction: fasteners are placed only within the hollows of the posts, with an air gap between the interior of the post and the fastener. However, in contrast to the solution of the ‘609 patent, the present inventors have surprisingly found that it is possible to drive fasteners directly through the thickness of the light-guide plate without creating light leaks or noticeable variances in light emission.

[0057] FIG. 8 is a top plan view of a light-guide plate assembly, generally indicated at 200, according to another embodiment of the invention. In this embodiment, the light-guide plate assembly 200 is a several-component assembly; the light guide 202 itself is visible in the view of FIG. 8. The light guide 202 has a lightreleasing surface pattern 204 that covers much of its surface area on one side. Additionally, arrayed along the edges of the light guide 202 are a series of fasteners 206.

[0058] FIG. 9 is a cross-sectional view taken through Line 9-9 of FIG. 8. The light-guide plate assembly 200 comprises, in order from top to bottom, the lightguide plate 202 itself, a thin reflective sheet 208, and a backing panel 210. The backing panel 210 in this embodiment is made of plywood, but in other embodiments, it may be plastic, metal (e.g., sheet metal) or some other material, as described above for the underlayment / overlayment 30. The fasteners 206 extend through all three components 202, 208, 210 and are secured on the reverse of the backing panel 210. More specifically, in the illustrated embodiment, the fasteners 206 are flat-head machine screws that are secured by complementary nut structure 212 within a counterbore 214 in the backing panel 210. In other embodiments, the “sense” could be reversed: the fastener could extend from the backing panel 210 toward the light-guide plate 202 and could be secured by a nut or other such structure that sits atop the light-guide plate 202.

[0059] In FIGS. 8-9, the fasteners 206 are shown as being used along the edges of the light-guide plate assembly 200. In one embodiment, for example, the fasteners 206 could be placed at a pitch of about one per foot (0.3 m) along the edges of the light-guide plate assembly 200. More or fewer fasteners 206 could be used.Additionally, while the fasteners 206 are shown arrayed around the edges, surprisingly, fasteners 206 can be driven through the central area of the light-guide plate assembly 200 (i.e., the light-emitting area of the light-guide plate assembly 200) without causing noticeable light leaks or other visual disturbances in the uniform conduction and emission of light across the light-guide plate assembly 200. However, the present inventors have found that it is helpful to consider the color and finish of the fasteners 206. More specifically, while any fastener color or finish may be used, the present inventors have found that fasteners that are metallic silver or gray are less likely to cause noticeable visual disturbances than fasteners that are white or black.

[0060] A light-guide plate assembly 200 that comprises a light-guide plate 202 fastened to a reflective sheet 208 and a backing panel 210 can be used in place of the similar structures described above without compromising the ability of lighting 40, 100, 166 to be removed and replaced as needed.

[0061] In a typical use of the light-guide plate 202, the fastener 206 may be a self-tapping fastener that forms its own hole. Holes may also be drilled or formed in some other suitable fashion before the fastener 206 is inserted.

[0062] FIG. 10 is a top plan view of a light-guide plate 300 according to another embodiment, and FIG. 11 is a side elevational view. The light-guide plate 300 of FIGS. 10-11 is rectangular in shape. This light-guide plate 300 has several features that make it particularly suitable as a stock material for use in making light-guide plates for specific installations. For one, the light-guide plate 300 has pre-formed holes 302 arranged at a regular pitch or pitches across substantially the entire surface of the lightguide plate 300. In this case, each hole 302 is shaped for a flat-head screw and flares out at the top of the hole 302 to accommodate the head.

[0063] Pre-forming holes 302 in the light-guide plate 300 ensures that the holes 302 are consistent in their characteristics and makes it less likely that burrs or other inconsistencies in the holes might cause problems with even light distribution and emission. Depending on the characteristics of the holes 302 and other factors, they may be drilled, laser-cut, molded into the light-guide plate 300, or formed in any other suitable manner. Additionally, the pre-formed holes 302 may save time during final assembly. Because the holes 302 are distributed uniformly across the light-guide plate 300, the light-guide plate 300 may be cut into essentially any shape or size and holes 302 will be present in predictable locations in the cut piece.

[0064] The pitch at which the holes 302 are spaced may not be the same in one direction along the light-guide plate 300 as it is in another direction along the lightguide plate 300. For example, in one embodiment, the light-guide plate 300 may be 4mm (0.04 in) thick, with a long-side length of 2440mm (96 in) and a short-side length of 1220mm (48 in). With that sizing, the holes 302, 7.5mm (0.3 in) in maximum dimension and 4mm (0.16 in) in shaft diameter, may be arranged at a pitch of 234mm (9.21 in) between holes 302 in long-side rows, shown as pitch “A” in FIG. 10, and of 224mm (8.82 in) between rows, shown in pitch “B” in FIG. 10.

[0065] Light-guide plates 300 may have other features as well. For example, a light-guide plate 300 would typically have a light-releasing surface pattern, like the light-releasing surface pattern 38, on at least the upper (i.e., panel-facing) side. This pattern is not shown in FIGS. 10-11 so as not to obscure the details of the holes 302.

[0066] The description above assumes that a light-releasing surface pattern, like the surface pattern 38, is uniform in arrangement and extent. However, that need not be the case in all embodiments. There are certain situations in which a non-uniform light-releasing surface pattern may be used to encourage uniform light emission. For example, if a light-guide plate 300 is lit from only one edge, there will be a fall-off in light as one moves from the edge at which the light originates toward the opposite edge. In practical terms, if a countertop is lit only from the front edge, there will be a falloff in light near the rear of the countertop, toward the backsplash. In a case like this, it may be helpful to have a light-releasing pattern that is more dense where the falloff in light is expected to be greatest. In this way, the more-dense light releasing pattern may compensate for the fact that less light is available at a particular position.

[0067] FIG. 12 is a top plan view of a light-guide plate, generally indicated at 350, that embodies this principle. The light-guide plate 350 of FIG. 12 has the regular pattern of holes 302 described above and also has an additional feature: as shown, the light-releasing surface pattern, generally indicated at 352, varies in density across the surface of the light-guide plate 350. The light-releasing surface pattern 352 of the illustrated embodiment uses bands of density: bands of lighter density 354 extend parallel to the long axis of the light-guide plate 350 near its lateral edges. Adjacent to and inward of the bands of lighter density 354, closer to the center of the light-guide plate 350 are bands of medium density 356. At the center of the light-guide plate 350,extending along the long axis, is a band of high density 358. Of course, in other embodiments, a continuous gradient may be used that, e.g., ranges from a lighterdensity surface pattern at the long edges to a high-density surface pattern at the center, along the longitudinal axis.

[0068] As with typical light-releasing surface patterns 38, the lightreleasing surface pattern 352 may be formed by laser inscription, indentation, abrasion, or any other useful technique. The particulars of which parts of a light-guide plate 350 have a high-density light-releasing pattern and which parts have a low-density lightreleasing pattern will depend on the configuration of the light-guide plate 350 and how it is intended to be cut and used. In this example, the light-guide plate 350 is intended to be used as stock for final or finish manufacturing. If the light-guide plate 350 is cut along its long axis, the result will be two plates, each one having a lighter-density lightreleasing pattern 354 along one long edge and a high-density light-releasing pattern 358 along the other long edge. In a practical installation, the resulting cut light-guide plate (comprising one-half of the light-guide plate 350, cut along the long, central axis) would be oriented with the edge having the lighter-density light-releasing pattern 354 facing the light emitter and receiving the light, with the high-density light-releasing pattern 358 along the opposite edge, farthest away from the light emitter.

[0069] FIG. 13 is a cross-sectional view similar to the view of FIG. 3, illustrating a backlighting system 400, including a light source 402 and a light-guide plate 350 installed beneath a countertop 14. As in the description above, the countertop 14 has a skirt or lip 20.

[0070] The light-guide plate 350 is secured to a substrate 404, which, in this illustration, is a sheet of wood. Between the light-guide plate 350 and the substrate 404 is a reflector in the form of a reflective sheet 406. A fastener 408 is driven directly through the light-guide plate 350 and reflective sheet 406 into the substrate 404. In this embodiment, since the substrate 404 is wood, the fastener 408 is a wood screw, although machine screws, rivets, and other types of fasteners 408 may be used. In the illustrated embodiment, no particular securement structure is used on the fastener 408, because the bite of the fastener 408 into the wood substrate 404 is sufficient, but if the substrate is particularly thin, e.g. thin plywood or sheet metal, securement structure, such as a nut, may need to be used.

[0071] The backlighting system 400 also includes a slightly different light source 402 than the light sources 40, 42 described above. More specifically, the body 412 of the light source 402 comprises a single layer or piece of light-guide material, such as polycarbonate or poly(methyl methacrylate). The body 412 is thin and rectangular in cross-section, having a thickness typical of that for a light-guide panel, e.g., 4-5mm. A light-emitter 414 emits into the bottom edge 416 of the body 412. The light emitter 414, like those described above, may be, e.g., a strip of LED linear lighting. The light-emitter 414 is coupled to the body 412 by means of a J-channel 418 of the sort that would traditionally be used in a conventional light-guide panel. The J-channel 418 is secured to the body with light-occlusive tape 420.

[0072] On one side of the body 412, a reflector, in the form of a reflective sheet 422, is attached. More specifically, the light source 402 is arranged such that it projects light outward, into the depending skirt or lip 20, and also inward, into the lightguide plate 350. For that reason, the body 412 may have a uniform or non-uniform light-releasing pattern on the surface 424 facing the skirt or lip 20. The edge 410 of the body 412 opposite the light emitter 414 is capped with a second channel 426 that has a more complex shape: the second channel 426 extends over the edge 410 and, on the inward-facing side 427 of the body 412, adjacent the light-guide plate 350, the second channel 426 forms a slot 428 for a second light emitter 431 that emits light into the light-guide plate 350. The slot 428 in the second channel 426 has two laterally- extending sidewalls 430, 432 and a bottom 434. The second light emitter 431 is again a strip of LED linear lighting and is placed on the bottom 434 of the slot 428. The second channel 426 is secured to the body 412 with light-occlusive tape 436, 438, 440. On the inward-facing side 427, the tape 438 is installed overtop the reflective sheet 422.

[0073] The arrangement described above assumes that the light source 402 will be installed in an area that is not expected to be particularly wet, or to have other environmental hazards that would damage the light emitters 414, 431. If the light source 402 is installed in a location where conditions could potentially involve more exposure to contaminants (e.g., water, water vapor, chemicals, dirt, etc.), then the J- channel 418 and the slot 428 could be filled with an encapsulant, such as a polyurethane or a silicone polymer, to prevent those contaminants from reaching the light emitters 414, 431. The encapsulant may be, e.g., a two-part resin that is poured into the J- channel 418 and the slot 428 over the light emitters 414, 431 and caused or allowed tocure. That is, the resin may be caused to cure, e.g., by exposure to elevated temperatures, specific forms of radiation (e.g., UV light), or other types of energy, or allowed to cure under ambient conditions (e.g., by a chemical reaction that proceeds at ambient temperature, by exposure to ambient moisture, etc.). The resulting encapsulation may be complete, i.e., the light emitters 414, 431 are completely surrounded by the encapsulant, or partial, i.e., the light emitters 414, 431 are partially covered or partially surrounded by the encapsulant. In practical terms, for complete encapsulation, the J-channel 418 and the slot 428 would typically be completely filled, whereas in a partial encapsulation, encapsulant may simply be dripped over the light emitters 414, 431, leaving most of the J-channel 418 and the slot 428 unfilled.

[0074] In some cases, one of the J-channel 418 or the slot 428 may be filled with an encapsulant while the other is not. As one example of this, in FIG. 13, the area of the J-channel 418 around the light emitter 414 is filled with an encapsulant 440. While the encapsulant 440 is shown as solid around the light emitter 414, air gaps between the light emitter 414 and the encapsulant 440 may be used.

[0075] While not specifically shown in FIG. 13, the light source 402 may be taped in place, wedged in place with a shim, caulked, or secured in some other way.

[0076] Compared with the light sources 40, 42 described above, the light source 402 is smaller, simpler, and uses components, like the body 412 and J-channel 418, that are easily made of light-guide panel stock materials. The use of a light-guide plate 350 with pre-formed holes 302 makes for easy attachment of the reflective sheet 406.

[0077] FIG. 14 is a cross-sectional view similar to the view of FIG. 13, illustrating a light source 500 of somewhat different construction. More specifically, the light source 500 uses two rigid metal or plastic extrusions 502, 504 that are shaped for the application. The extrusion 502 is U-shaped or cup-shaped and covers the bottom of the body 506 of the light source 500, enclosing and providing a mounting surface for the light emitter 414 that emits light upwardly into the body 506. As in the embodiment of FIG. 13, the light emitter 414 may be encapsulated within the extrusion 502.

[0078] The extrusion 504 at the top of the light source 500 is somewhat more complex. It defines a channel 508 that fits over the top of the body 506. That channel has two legs 510, 512 that, in the orientation of FIG. 14, extend downwardly over the body 506. However, unlike in the extrusion 502 at the bottom of the body 506,the extrusion 504 at the top has legs 510, 512 of unequal lengths. Specifically, the leg 510 that extends toward the depending lip 20 of the panel 14 is shorter than the leg 512 on the other side of the body 506. This is because the body 506 is adapted to emit light toward the lip 20 to backlight the lip 20. Thus, shortening the leg 510 of the extrusion 504 allows more exposure of the body in order to emit light. By contrast, the other side of the body 506 has a reflector 514, which the leg 512 and the bottom extrusion 502 hold in place; therefore, it is immaterial how much of that surface is covered by the leg 512. Although the bottom extrusion 502 has legs of equal length, creating its U- or cup-shape, in some embodiments, that extrusion 502 may also have legs of unequal lengths to maximize the light-emission area 507 of the body 506.

[0079] The extrusion 504 at the top of the body 506 has two flanges: a vertical flange 514 is aligned with the leg 510 but extends in the opposite direction: upwardly, toward the underside of the panel 14. The vertical flange 514 extends straight up for a length, and then curves inwardly, such that when it terminates, the edge of the vertical flange 514 faces the light-guide plate 350. The second light emitter 518 is mounted on the inside of the vertical flange 514, oriented to emit light toward and into the light-guide plate 350.

[0080] Additionally, a horizontal flange 520 extends outwardly from the junction of the leg 512, level with the top of the extrusion 504. The horizontal flange 520 extends horizontally to the substrate 404 in this embodiment. This has the effect of at least partially isolating the second light emitter 518 and helping to ensure that its light enters the light-guide plate 350. As is visible in FIG. 14, in this embodiment, the second light emitter 518 is not particularly well aligned with the edge of the light-guide plate 350. However, by at least partially preventing the light from the second light emitter 518 from escaping the area, the horizontal flange 520 in this embodiment assists with the loose optical coupling between the light source 500 and the light guide plate 350.

[0081] In some cases, the horizontal flange 520 may help to suspend the light source 500 in place, with mounting hardware, by creating a tight fit, etc. However, as with other embodiments, the light source 500 may be secured in place with tape, adhesives, a shim, etc. if desired.

[0082] In the above, the description uses the term “extrusion” to refer to certain components 502, 504. The use of this term implies that the components 502,504 in question have constant cross-sections over their lengths. In many cases, these components will be made by extruding metal or plastic. However, particularly in shorter lengths, the components may be cast, additively manufactured, or made in some other way. Thus, for purposes of this description, the term “extrusion” should be construed to cover any component with a constant cross section over its length, regardless of the process by which it is formed. As those of skill in the art will recognize, in the description above, extrusions may be used in many cases instead of tape.

[0083] Depending on the embodiment and the particulars of the installation, it may or may not be necessary to cover or seal the ends of the light source 500 to prevent light leaks at the ends. If it is necessary or desirable to seal the ends of the light source 500, that may be done in any convenient way, e.g., by using shaped caps that fit over the ends, by the use of light-occlusive tape, or by other means.

[0084] This description uses the term “about.” When that word modifies a number or a numerical range, it means that the specified number or range may vary so long as the described end result remains the same. If it cannot be discerned what range would not affect the described end result, the term “about” should be read to mean ±10%. This description also uses directional terms, like “depending.” As those of skill in the art will realize, all such directional terms are used with respect to the coordinate system(s) of the drawing figures for descriptive convenience only. The actual direction or relative location of one component as compared with another will vary depending on the installation and the perspective of the observer.

[0085] While the invention has been described with respect to certain embodiments, the description is intended to be exemplary, rather than limiting. Modifications and changes may be made within the scope of the invention, which is defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A backlighting system, comprising: a light-guide plate having a main emitting surface and a reverse surface, the main emitting surface having light-releasing structure; a reflector installed on the reverse surface of the light guide; and a light source indirectly and removably optically coupled to the light-guide plate, such that first light from the light source is emitted into an edge of the light-guide plate.

2. The backlighting system of claim 1, wherein the first light source includes a first light-emitting element arranged to emit the first light into the edge of the lightguide plate.

3. The backlighting system of claim 2, wherein the first light source includes: a translucent body that serves as a light guide with at least one emitting surface; and a second light-emitting element directly optically coupled to the body to emit second light into the body.

4. The backlighting system of claim 3, wherein the first light-emitting element is mounted on the body and emits the first light in a direction away from the body.

5. The backlighting system of claim 3, wherein the at least one emitting surface of the body of the light source faces away from the light-guide plate when the first light source is optically coupled to the light-guide plate.

6. The backlighting system of claim 3, further comprising: a first extrusion that covers a bottom of the body, the first extrusion enclosing and optically coupling the second light-emitting element to the body; and a second extrusion that covers the top of the body, the second extrusion mounting the first light-emitting element.

7. The backlighting system of claim 6, wherein the second extrusion comprises: a vertical flange on which the first light-emitting element is mounted; and a horizontal flange; wherein the second extrusion fits on the body such that more of a first side of the body is exposed than a second side of the body.

8. The backlighting system of claim 1, further comprising: a substrate; and one or more fasteners; wherein the one or more fasteners are driven through the light-guide plate and the reflector and into the substrate.

9. The backlighting system of claim 8, wherein the light-guide plate has one or more pre-formed holes in a light-emitting area thereof, the pre-formed holes being sized and adapted to accept the one or more fasteners.

10. The backlighting system of claim 1, wherein the light-releasing structure comprises a light-releasing pattern in the emitting surface.

11. The backlighting system of claim 10, wherein the light-releasing pattern is at least substantially uniform across the main emitting surface.

12. The backlighting system of claim 11, wherein the light-releasing pattern has a continuous or banded density gradient.

13. A backlit panel, comprising: a panel having an obverse side, a reverse side, and a depending lip; a light-guide plate installed on the reverse side of the panel; a reflector installed on a reverse side of the light-guide plate; and a light source installed removably under the depending lip and arranged such that the light source emits first light into the light-guide plate.

14. The backlit panel of claim 13, wherein the light source includes a first lightemitting element arranged to emit the first light into the edge of the light-guide plate.

15. The backlit panel of claim 14, wherein the first light-emitting element is mounted on the body and emits light in a direction away from the body.

16. The backlit panel of claim 13, wherein the light source includes: a translucent body that serves as a light guide with at least one emitting surface; and a second light-emitting element directly optically coupled to the body to emit second light into the body.

17. The backlit panel of claim 16, wherein the first light-emitting element and the second light-emitting element are at least partially encapsulated by a resin.

18. The backlit panel of claim 13, wherein the light source is wedged, adhered, or taped in place under the depending lip.

19. The backlit panel of claim 13, further comprising a backing plate to which the light-guide plate and the reflector are secured.

20. The backlit panel of claim 19, further comprising fasteners extending through the light-guide plate and the reflector to the backing plate.

21. The backlit panel of claim 20, further comprising a pattern of pre-formed holes through the light-guide plate, at least some of the pre-formed holes being in a light-emitting area of the light-guide plate.

22. The backlit panel of claim 13, wherein the light-guide plate comprises a light-releasing pattern on a side thereof facing the panel, the light-releasing pattern having a density gradient.

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