AU2009201078B2

AU2009201078B2 - Lighting Apparatus

Info

Publication number: AU2009201078B2
Application number: AU2009201078A
Authority: AU
Inventors: John Ferguson
Original assignee: FERGUSON LIGHTING Pty Ltd
Current assignee: FERGUSON LIGHTING Pty Ltd
Priority date: 2002-04-26
Filing date: 2009-03-17
Publication date: 2012-01-19
Anticipated expiration: 2023-04-23
Also published as: AUPS198202A0; AU2009201078A1; AU2003203834A1

Abstract

A lighting apparatus has an arrangement (2) which includes light sources (42), reflector means (54), and a window (14). The reflector means are configured for 5 reflecting, through the window, light that is transmitted from the light sources across the inner side of the window. The reflector means includes reflector elements in the form of prismatic lenses (58) which are angled relative to one another to distribute the reflected light over the window. The arrangement also includes baffle reflector plates (64) adjacent the light sources for blocking some of the light from the light sources. 10 The apparatus can be used for back lighting of translucent signs, and for room lighting. o. -o 0 ecc

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION - STANDARD PATENT 5 Lighting Apparatus FIELD OF THE INVENTION 10 This invention relates to a lighting apparatus. In one embodiment, the invention is for illuminating a sign, while in another embodiment, the invention is for illuminating a room. SUMMARY OF THE INVENTION 15 According to a first aspect of the invention, there is provided a lighting apparatus having an arrangement, the arrangement including: window means defining a lighting window; at least one light source disposed adjacent an edge of the window, at an inner 20 side of the window relative to the apparatus, and configured to transmit light rays across the inner side of the window; and at least one reflector means corresponding to each light source, disposed opposite the window at said inner side, for reflecting, through the window, light passing directly from the corresponding light source to the relevant reflector means, 25 each reflector means having portions which are angled with respect to one another so as to reflect the light from the corresponding light source such that the reflected light is distributed over at least part of the window. The portions of each reflector means are preferably constituted by a plurality of 30 reflector elements. Preferably, each reflector means is constituted by a sheet and said reflector elements of that reflector means are constituted by a plurality of juxtaposed 2 reflective prismatic lenses which are part of the sheet. Then, preferably, each reflector means is curved such that the reflector elements of that reflector means are disposed successively closer to the window in a direction away from the corresponding light source. 5 In one preferred embodiment, each reflector means is substantially planar, and orientated such that the reflector elements of that reflector means are disposed successively closer to the window in a direction away from the corresponding light source. 10 Also in a preferred embodiment, the arrangement includes a plurality of said light sources, and a plurality of said reflector means each corresponding to a respective light source. In this case, in one embodiment, each reflector means of the arrangement is in the form of a substantially planar panel, the panels being disposed to 15 form, together, a pyramid shape. The panels may be integrally joined to one another. Preferably, the panels disposed to form a pyramid shape are positioned substantially symmetrically about two centre lines of the arrangement, which centre lines are perpendicular to each other, each bisecting the arrangement along a respective orthogonal axis of the arrangement. 20 In one preferred embodiment, the arrangement includes four light sources disposed in a rectangular configuration. Also in a preferred embodiment, the arrangement includes a pair of said light sources, 25 and a pair of said reflector means each corresponding to a respective light source. In this case, preferably, the light sources and reflector means of each said pair are disposed substantially symmetrically about a centre line of the arrangement. Preferably, the arrangement includes a curved sheet, and the reflector means of said pair of reflector means are integral parts of the curved sheet. 30 In one embodiment, the arrangement includes two said windows opposite each other and a pair of similar said curved sheets which are superposed on each other and 3 arranged so that corresponding edges of the sheets abut each other and the centres of the sheets are spaced from each other. Preferably, the arrangement includes side walls and a substantially planar back wall, 5 the side walls, the back wall and the window defining a chamber. At least part of the back wall is preferably reflective. In this case, each reflector means is preferably disposed on a reflective part of the back wall. Preferably, each light source includes at least one elongate lighting means, and each 10 elongate lighting means is preferably constituted by a fluorescent tube. In a preferred embodiment, at least one light source is constituted by a plurality of elongate lighting means. 15 Preferably, the arrangement includes at least one baffle plate corresponding to, and adjacent, each light source, at the same side of the respective light source as the reflector means corresponding to that light source, each baffle plate allowing direct transmission of light from that light source to the corresponding reflector means. Preferably, also, at least one light source includes a plurality of elongate lighting 20 means, and the arrangement includes a plurality of said baffle plates each corresponding to a respective elongate lighting means. Each baffle plate is preferably a baffle reflector having a reflective face and being configured for reflecting, through the window, light emanating directly from the corresponding light source. Preferably, each baffle plate is configured for blocking, from the window, some light emanating 25 directly from the corresponding light source and some light from that light source that has reflected off a surface of the apparatus at an opposite side of the respective baffle plate to the window. In one embodiment, the window is orientated in a general window plane and each baffle plate is orientated in a respective baffle plate plane which is angled relative to the window plane. 30 In a preferred embodiment, the window is at a front of the arrangement and said plurality of elongate lighting means of said at least one light source consists of a pair 4 of elongate lighting means, substantially aligned with each other, one positioned behind the other. Preferably, the arrangement includes a respective back reflector corresponding to, and 5 disposed adjacent, each light source, at an opposite side of the light source to the reflector means corresponding to that light source. Each back reflector preferably includes three substantially planar joined reflector panels which are angled relative to one another. 10 In one preferred embodiment, each said light source is a primary light source, the arrangement including at least one supplementary light source, wherein each supplementary light source corresponds to, and is aligned with, a respective primary light source such that the supplementary light source and corresponding primary light source together lie in a general plane which is substantially parallel to the window. 15 Each supplementary light source preferably includes at least one supplementary elongate lighting means. Preferably, each supplementary elongate lighting means is constituted by a fluorescent tube. In a preferred embodiment, the arrangement includes at least one supplementary 20 reflector, each supplementary reflector being positioned between a respective supplementary light source and the corresponding primary light source. Preferably, each supplementary reflector is at least partly wedge-shaped, so as to taper in a direction from the respective primary light source to the corresponding supplementary light source. 25 In one preferred embodiment, the panels of each back reflector are disposed to extend, together, partially around the corresponding light source. In another preferred embodiment, in respect of each primary light source having a 30 corresponding supplementary light source, the panels of the corresponding back reflector are disposed to extend, together, partially around the corresponding supplementary light source.

5 In a preferred embodiment, the arrangement is substantially free from any obstruction of light transmittance, between each reflector means and the window. 5 According to a second aspect of the invention, there is provided a lighting apparatus having an arrangement, the arrangement including: window means defining a lighting window; at least one light source disposed at a respective first position adjacent an edge of the window, at an inner side of the window relative to the apparatus, and 10 configured to transmit light rays across the inner side of the window; and at least one baffle plate corresponding to, and adjacent, each light source at a respective second position, each baffle plate permitting the direct transmission of light, from the corresponding light source, past that baffle plate and across the inner side of the window, in a direction parallel to a direction from the first position to the 15 second position. Preferably, each light source includes a plurality of elongate lighting means, and a plurality of baffle plates each corresponding to a respective elongate lighting means. Preferably, also, each baffle plate is a baffle reflector having a reflective face and 20 being configured for reflecting, through the window, light emanating directly from the corresponding light source. Each baffle plate is preferably configured for blocking, from the window, some light emanating directly from the corresponding light source and some light from that light source that has reflected off a surface of the apparatus at an opposite side of the respective baffle plate to the window. In one embodiment of 25 this aspect of the invention, the window is orientated in a window plane and each baffle plate is orientated in a respective baffle plate plane which is angled relative to the window plane. In one embodiment of the above aspects of the invention, the apparatus has a plurality 30 of said arrangements, which are preferably disposed in series. In this case, preferably, the series of arrangements is symmetrical about a centre line of the apparatus.

6 In one preferred embodiment of the above aspects of the invention, the lighting apparatus is configured for attachment of a translucent sign over the window, for illuminating the sign. 5 In another preferred embodiment of the above aspects of the invention, the lighting apparatus is configured as room lighting for illuminating a room. In a further form, the invention provides an apparatus for producing substantially uniform illumination through a window of a lighting device with side walls and a back 10 wall opposing the window, comprising: a means for lighting within the lighting device, a means for reflecting back-light from a side of the lighting means generally towards an opposing side of the lighting means, a means for diffusing light by reflecting a first fraction of the light generally towards the window and for refracting a second fraction of the light through the diffusing means and generally towards the 15 back wall and a reflective portion of the inner surface of the back wall, opposing the diffusing means. Wherein the reflective portion of the back wall reflects back at least a proportion of the second fraction of light generally towards the diffusing means whereby a third fraction of light is refracted through the diffusing means and generally towards the window. 20 In an alternate form, the invention may provide a method for producing substantially uniform illumination through a window of a lighting device comprising the steps of: (a) providing a lighting device enclosure with side walls, a back wall and the window opposing the back wall; 25 (b) providing a light source proximal a side wall; (c) reflecting light from a portion of the light source proximal the side wall generally towards an opposing side of the light source; (d) diffusing the light for substantially uniform illumination of the window by further steps of: 30 (i) providing a diffusing sheet which reflects a first fraction of light generally towards the window and refracts a second fraction of light through the diffusing sheet and generally towards the back wall; 7 (ii) reflecting at least a first proportion of light between the diffusing sheet and the back wall adjacent the diffusing sheet; and (iii) refracting at least a second proportion of light, reflected from the back wall, through the diffusing sheet and generally towards the 5 window. Preferably an apparatus for producing substantially uniform illumination through a window of a lighting device may be produced by the method described above. In further forms, the invention may provide an apparatus for producing substantially 10 uniform illumination through a window of a lighting device as substantially described herein and/or a method for producing substantially uniform illumination through a window of a lighting device as substantially described herein. The present invention aims to provide an alternative apparatus and/or method for a 15 lighting device which overcomes or ameliorates the disadvantages of the prior art, or at least provides a useful choice. Further forms of the invention are as set out in the appended claims and as apparent from the description. 20 BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 25 Figure 1 is a schematic perspective view of a lighting apparatus according to an embodiment of the invention; Figure 2 is a schematic perspective view of a component of the apparatus of Figure 1; Figure 3 is a schematic perspective view of a further component of the 30 apparatus of Figure 1; Figure 4 is a schematic elevation of an inner surface of part of the component of Figure 3; 8 Figure 5 is a schematic exploded section view through the apparatus of Figure 1, showing some of the components only; Figure 6 is a schematic perspective view of part of the interior of the apparatus of Figure 1; 5 Figure 7 is a schematic section along the line VII-VII in Figure 6; Figure 8 is a schematic cross-section through part of another embodiment of the apparatus showing two aligned light sources; and Figure 9 is a schematic cross-section through part of yet a further embodiment of the apparatus showing a supplementary light source and a wedge-shaped reflector. 10 DETAILED DESCRIPTION Referring to Figures 1 to 7, there is shown an electrically powered lighting apparatus. The apparatus has an arrangement, designated 2, which includes a base 4, which in 15 turn includes side walls 6 and a back wall 8. Attached to the side walls 6 are ledges 10 (see Figures 6 and 7) on which is supported an inner frame 12 (see especially Figures 3 and 4) which defines the borders of a window 14. The side walls 6, back wall 8 and inner frame 12 together define an inner 20 chamber 16 of the apparatus. A translucent sheet 18, of acrylic or other suitable material, covers the window 14 and has edges 20 which overlap the inner frame 12 as shown in Figure 3. The translucent sheet 18 is secured to the inner frame 12 at the overlapping edges 20, by way of adhesive or other suitable securement means (not shown). In one embodiment, the translucent sheet 18 has light transmitting 25 characteristics similar to those of opal glass while in another embodiment, the translucent sheet is clear and transparent. The inner frame 12 has screw holes 22 which are aligned with corresponding screw holes 22 in the ledges 10. The inner frame 12 is secured to the base by screws (not 30 shown) passing through the screw holes 22 of the inner frame into those of the ledges 10, as indicated by the broken lines 24 in Figure 5. On the inner surface of the inner frame 12, spaced from each of two opposite edges 26, are a pair of parallel strips 28 9 and 29 (as shown in Figure 4). The inner strip 28 of each pair of strips is non reflective matt-black or of other non-reflective colour, while the outer strip 29 of each pair is highly reflective. 5 The arrangement 2 also includes an outer frame 32 similar to the inner frame 12, the outer frame defining an aperture 34. A clear sheet 36 of glass, perspex or other suitable material, is attached to the outer frame 32 and extends over the aperture 34. Adhered to the outer frame 32 are attachment patches 38, each constituting one part of 10 a hook-and-loop fastener, or a similar fastener such as that of the interengaging-stalk type. Complementary attachment patches 40, each constituting the other part of a respective fastener, are adhered to the inner frame 12. The patches 38 and 40 allow the outer frame 32 to be releasably secured to the inner frame 12, and hence to the base 4. 15 The arrangement 2 includes two light sources, each being a lighting means in the form of an elongate, electric fluorescent tube 42. The tubes 42 are disposed on opposite sides of the base 4. In other embodiments (see for example Figures 8 and 9), each light source may include two or more tubes instead of a single tube, and these, in 20 different embodiments, may be arranged in series, or aligned with each other; for instance, they may be a pair of tubes, one behind the other. Each tube 42 is disposed adjacent a respective edge of the window 14, that is, at two opposite edges of the window. Thus, the tubes 42 may be considered as being 25 disposed symmetrically with respect to an imaginary line 44 (see Figure 6) which substantially bisects the back wall 8 and hence the arrangement 2. Each tube 42 is electrically connected to a mounting 46 which, in turn, is attached to a bracket 48, and each bracket is joined to the back wall 8 (see Figure 6). The mountings 46 are electrically connected (in a manner not shown) to an electric cable 50 extending 30 through a cable hole 52 (see Figure 1) in one of the side walls 6, to allow the arrangement 2 to be connected to an electric power supply.

10 Disposed between the fluorescent tubes 42 is a reflector means in the form of a curved sheet 54 (see Figures 6 and 7) which is attached to the back wall 8 by adhesive 56 (as shown in Figure 7) or in any other suitable way. The sheet 54 defines reflector elements in the form of an array of juxtaposed prismatic lenses 58. It will be 5 appreciated that, as a result of the curvature of the sheet 54, the centre of the sheet (corresponding with the line 44) is closer to the window 14 than are the two opposite edges 60 of the sheet, adjacent the fluorescent tubes 42 (only one edge 60 being shown in figures 6 and 7). The sheet 54 is maintained in its curved configuration by a spacer 61 which keeps the centre part of the sheet spaced from the back wall 8. The 10 sheet 54 is configured to be substantially symmetrical about the line 44. In another embodiment of the invention (not shown), instead of the curved sheet 54, there is provided a plurality of individual planar reflective elements, angled relative to one another and, in one embodiment, arranged substantially along a curved path. These elements together, as a result of their respective orientations, are configured to achieve 15 a similar performance (as discussed below) to the curved sheet 54. Most of surface of the back wall 8, including that behind the sheet 54, is reflective. Adjacent each tube 42 is a plate 64 which constitutes a baffle reflector, which is on the 20 same side of the respective tube 42 as the sheet 54. The front surface 66 of each plate 64 is highly reflective while the opposite, rear surface 68 is non-reflective matt-black or of other non-reflective colour. Each plate 64 is supported, on the back wall 8, by spacers 70. Further spacers 72 extend above the plate 64 as well, for providing support to the inner frame 12 when it is mounted on the base 4. In another 25 embodiment (see, for example, Figure 9), each plate 64 is angled relative to the back wall (and relative to the general plane of the window 14), by an angle of, for instance 10 degrees, so that the front surface 66 of the plate faces somewhat away from the light source 42. In yet another embodiment (see, for example, Figure 8), there are more than one baffle reflector adjacent each light source 42. 30 In the embodiment of Figures 1 to 7, immediately behind the plate 64, the there is a strip 74 on the back wall 8, which is matt-black or of other non-reflective colour.

l1 Disposed adjacent each tube 42, on an opposite side to the sheet 54, is a back reflector 76. Each back reflector 76 includes three reflector panels 78 which are angled relative to each other so that the back reflector extends partially around the respective tube 42 5 (as may be seen in Figure 7). The surfaces of each panel 78 facing the respective tube 42 are highly reflective. Between the corresponding ends of each tube 42, there is disposed a respective edge reflector 80 (see Figure 6). Each edge reflector 80 has an upper surface 82 and two 10 front surfaces 84 which are angled relative to each other. The angle between the two front surfaces 84, in one embodiment, is 20 degrees. The arrangement 2, in one form, is used to illuminate a translucent sign (not shown), for example in the form of a graphic on a translucent or transparent backing sheet. As 15 described above, the inner frame 12 is screwed to the ledges 10 to secure it to the base 4. The sign is placed on the translucent sheet 18 so as to extend over the window 14. Once the sign is in place, the outer frame 32 is secured to the inner frame 12 by means of the attachment patches 38 and 40, as described above, thereby sandwiching the sign between the inner and outer frames, and holding it in place. It will be appreciated that 20 the sign can then be viewed through the clear sheet 36 and aperture 64 of the outer frame 32. Means (not shown) are provided for removing the outer frame 32 from the inner frame 12 to allow the sign to be removed or replaced. These means for removing the outer frame 32, in one embodiment, include a small hole in the outer frame, into which an appropriate hook can be inserted to pull the outer frame free. 25 To illuminate the sign, the tubes 42 are switched on, by providing them with electric power via the electric cable 50. Light rays from the tubes 42 are transmitted to the curved sheet 54, to the baffle reflector plates 64, to the back reflectors 76, to the inner surface of the inner frame 12, to the edge reflectors 80, and to the back wall 8, as will 30 be described further below, and ultimately through the window 14 (and, in a relevant embodiment, through the translucent sign, to illuminate the sign). Where the sign is in the form of a graphic on a translucent, but not transparent, backing, then the 12 translucent sheet 18 may be clear and transparent. This is because the non transparency of the sign will prevent the inside of the chamber 16 being viewed, and this purpose need not be served by the translucent sheet 18. However, where the backing of the sign is transparent, then to avoid the inside of the chamber 16 being 5 viewed, the translucent sheet 18 may have similar light transmitting characteristics to opal glass. The light transmitted onto the curved sheet 54 is reflected by the prismatic lenses 58 towards the window 14 as indicated by the arrow 86 in Figure 7. The curved shape of 10 the sheet 54 and the resultant orientation of the individual lenses 58 have the effect of distributing the reflected light substantially over the window 14. In other words, these features result in the reflected light being distributed in this manner rather than, for instance, being reflected in a concentrated beam, or, for instance, being reflected with rays of the reflected light having the same directional relationship to one another as in 15 the light from the tubes which is transmitted onto the sheet 54. The distribution of light over the window 14 assists in establishing a more even illumination than would be the case in the absence of the curved sheet 54. In view of the curvature of the sheet 54, it will be appreciated that the sheet may be 20 considered as constituting two integral reflective means, arranged symmetrically about the line 44, each for reflecting direct light from a respective and corresponding one of the two oppositely disposed tubes 42 (only one of which is shown in Figures 6 and 7). If each tube 42, when viewed from an end, is considered as constituting, in effect, a 25 point-source of light, then it may be considered that the intensity of light emanating from the tube decreases in a direction away from the tube, as an inverse-square of the distance from the tube. As the centre of the sheet 54 (corresponding with the line 44 in Figure 6) is the furthest part of the sheet from each of the tubes 42, it is the part of the sheet experiencing the lowest intensity of light directly from the tubes. However, 30 as mentioned above, due to the curvature of the sheet 54, the centre of the sheet is also closer to the window 14 than are the edges 60 of the sheet which are adjacent the 13 tubes 42. This proximity to the window 14 at this position compensates, at least partially, for the reduced intensity of light transmitted onto the sheet 54. A small portion of the light transmitted onto the sheet 54 is refracted through the sheet 5 towards the reflective part of the back wall 8, from where it is reflected back to the sheet, as indicated by the arrows 88 in Figure 7. This reflected light is again refracted through the sheet 54 towards the window 14, as indicated by the arrow 90 in Figure 7. In larger embodiments of the invention (not shown), additional reflectors may be provided behind the sheet 54 (i.e. reflectors mounted on the back wall 14) to enhance 10 the reflection of such refracted light back towards the sheet 54. Each tube may be considered as being at a mean, first position which corresponds to the centre of the tube when the tube is viewed in cross-section as in Figure 7, and each baffle reflector plate 64 may be considered as being at a mean, second position which 15 corresponds to the centre of the plate when the plate is viewed in cross-section, also as in Figure 7. In accordance with this consideration, it will be appreciated that the plate 64 is configured and orientated to allow the transmission of light, from the tube 42, past the plate, in a direction substantially parallel to a direction from that first position to that second position, as indicated by that part of the arrow 86 above the sheet 54 in 20 Figure 7. The reflective front surface 66 of each baffle reflector plate 64 reflects light from the respective tube 42 towards the window 14, as indicated by the arrow 92 in Figure 7. However, the non-reflective rear surface 68 tends to reduce at least some of the 25 intensity of light from the tubes 42 reaching the window 14. This reduction in intensity is facilitated due to the blocking, by each reflector plate 64, of certain portions of light that, but for the reflector plate, would be transmitted directly through the window 14 from the respective tube 42, and certain portions of light, from the respective tube, that would be transmitted directly through the window after having 30 reflected off the back wall 8. The reduction in intensity is also assisted by the non reflective strips 74 of the back wall 8, which do not reflect light from the tubes 42. The reduction in intensity avoids excessive brightness of the light close to the light 14 sources 42, that is, near the edges of the window 14 (and hence, in relevant embodiments, near the edges of the sign being illuminated). Also contributing to this reduction of undesirable, overly bright areas of illumination, is the arrangement of the two pairs of strips 28 and 29 on the inner frame 12. The non-reflective strips 28 5 absorb some of the light while the reflective strips 29 reflect some of the light emanating directly from the tubes 42 and some of the light reflected by the baffle reflector plates 64. This reflected light is reflected back into the chamber 16, at least partly towards the curved sheet 54. 10 The back reflectors 76 reflect the light, emanating directly from the tubes 42, into the chamber 16, as indicated by the arrows 94 in Figure 7. Some of this reflected light may be reflected towards the baffle reflector plate 64 and some towards the sheet 54. As the back reflectors 76 are located on the opposite side of the tubes 42 to the sheet 54, it will be appreciated that the back reflectors provide for greater overall brightness 15 of light in the chamber 16 and on the window 14 (and hence, in relevant embodiments, also on the sign being illuminated), than would have been the case in the absence of the back reflectors. In the case of such an absence, a far greater portion of the light transmitted from the opposite sides of the tubes 42 would have been absorbed by the side walls 6 at those opposite sides. 20 As a result of the edge reflectors 80, much light that would otherwise have been absorbed by the side walls 6 behind these reflectors is reflected back towards the chamber 16, towards the window 14, and towards the curved sheet 54. As in the case of the back reflectors 76, the edge reflectors 80 contribute to the overall brightness of 25 light in the chamber 16 and that transmitted to the window 14 (and hence, in relevant embodiments, to the illuminated sign). It will be understood that, apart from the specific examples of reflection described above, the many reflective surfaces and their positions and orientations result in the 30 light which emanates from the tubes 42 reflecting and re-reflecting (i.e. "bouncing around") within the chamber 16, until either being absorbed by non-reflecting surfaces within the chamber, or being directed to the window 14. This light which is directed 15 to the window 14 contributes to the total illumination produced by the arrangement 2. In addition, the shape, position, and orientation of the various components described, contributes greatly to the evenness with which the light from the tubes 42 is directed through the window 14 (thereby assisting, in relevant embodiments, to illuminate the 5 sign evenly without undesirable bright spots or areas). In one embodiment of the invention (not shown) the arrangement 2 is configured to be double-sided - that is, to allow for signs to be displayed and illuminated on opposite sides of the arrangement. In such an embodiment, there are windows on the opposite 10 sides to allow for the illumination of both signs. In this embodiment, instead of a single curved sheet 54, there are two sheets superposed on, and attached to, each other, and curved so that their centres are bowed away from each other. At least one spacer (similar to the spacer 61) is used to keep the centres of the sheets apart from each other. 15 In one embodiment of the invention (not shown), instead of having a sheet 54 which is curved, there is provided a reflector means in the form of a single planar sheet or two abutting planar sheets (which may be separate from, or integral with, each other). Where one sheet is used, the arrangement may have a light source 42 at only one side 20 of the arrangement, with the sheet being disposed at the opposite side. Thus, the light source 42 will provide the required light intensity at the side of the arrangement 2 on which the light source is located, while the sheet will provide the required light intensity at the other side of the arrangement, by reflecting light from the light source. 25 Where two planar sheets are used, they may be configured to slope towards each other, so as to meet along an apex line which is aligned with the line 44, and which is closer to the window 14 than are the opposite edges of the sheets. Such a pair of sheets would play a similar role to the curved sheet 54 in the arrangement 2 described above, that is, each planar sheet would constitute a respective reflector means 30 corresponding to a respective one of a pair of oppositely disposed light sources 42.

16 In yet a further embodiment (not shown), the reflector means may include four triangular panels arranged in the form of a pyramid, with its apex closer than its base to the window 14 (the panels being separate from, or integral with, one another). In this case, the pyramid may be arranged symmetrically about the line 44. It would also 5 be symmetrical about another imaginary line, perpendicular to the line 44, bisecting the arrangement 2 in a direction perpendicular to that in which the line 44 bisects the arrangement. In this embodiment, to save space, an electronic ballast and other electrical or electronic components for powering the light sources 42 might be disposed behind the reflector means, with a reflective backing applied directly to the 10 rear surface of the reflector means in front of these components. Also in this embodiment, instead of having only two oppositely disposed light sources as in the case of the tubes 42 in the arrangement 2 described above, there may be a further two light sources, with all the light sources disposed in a rectangular or square configuration. In this case, each of the light sources may be a corresponding light 15 source to a respective one of the triangular panels making up the pyramid. In one preferred embodiment (not shown), instead of having a window 14 and aperture 34, defined by the inner frame 12 and outer frame 32, respectively, a window is defined, instead, by the side walls 6. In this case, in one embodiment, the side walls 20 6 may be provided with an outer extruded rim which may have a lip extending inwardly relative to the window. In these embodiments, because the window would effectively be borderless, or would have only a very narrow border, the light sources may be disposed directly behind the edges of the window - that is, within the projected area of the window. In this case, to prevent the intensity of the light 25 transmitted through the window (i.e. the light emanating directly from the light sources) being too high, a translucent but not transparent narrow plate is provided in front of each light source but behind the window, to diffuse the light before it reaches the window. The diffusers may be attached, by screws, to the lip. 30 Reference will now be made to the embodiments of Figures 8 and 9. In these embodiments, each feature having a reference numeral corresponding to that of a 17 feature described above, performs a similar function to the corresponding feature above. Referring firstly to Figure 8, there is shown another embodiment of the apparatus 5 described above. In this embodiment, each light source, generally designated 42, includes a pair of fluorescent tubes 42.1 and 42.2, which are arranged so as to be aligned with each other, one behind the other, relative to the window 14. For each light source 42, there is provided a pair of baffle reflector plates 64, each plate corresponding to a respective tube 42.1 or 42.2. Each of the baffle reflector plates 64 10 is similar to the baffle reflector plates 64 described above, and is supported on a spacer (not shown in Figure 8) which is similar to the spacers 70 and 72 referred to above. In this embodiment, there is a back reflector, generally designated 76, corresponding 15 to each tube 42.1, 42.2. The two back reflectors 76 are made up of a sheet 100 and a sheet 101. The sheet 100 is bent to form panels 102, 103, 104 and 105, while the sheet 101 is bent to form panels 106, 107, 108 and 109. The sheet 101 is superposed on the sheet 100 so that portions 110 and 111 of the sheet 100 extend beyond the ends of the panels 106 and 109, respectively. It will be appreciated that the panels 102, 106 20 and 107, and the portion 110, together serve, in relation to the tube 42.1, the functions of the panels 78 described above. Similarly, the panel 108, 109 and 104, and the portion I11, together serve, in relation to the tube 42.2, the functions of the panels 78 described above. 25 On the inner surface of the translucent sheet 18 of this embodiment, there is provided a black strip 112 which is aligned with the baffle reflector plates 64. This embodiment includes a side wall 6 to which is secured bracket 114, which include the ledges 10. A metal sheet 115 is attached to the ledges 10 by screws 116, 30 with the translucent sheet 18 being supported on this metal sheet. Attachment patches 38 and 40 are attached to the clear sheet 36 and metal sheet 115, respectively, for securing the clear sheet to the metal sheet.

18 Many of the lighting characteristics of this embodiment, in relation to each of the tubes 42.1 and 42.2 and their corresponding baffle reflector plates 64, are similar to those described in relation to the tube 42 illustrated in Figure 7. However, the 5 embodiment described with reference to Figure 8, and in particular the inclusion, by each light source 42, of a pair of tubes 42.1 and 42.2, assists in enhancing the overall lighting effect, and light intensity, that is produced. Turning now to Figure 9, there is shown yet a further embodiment of the apparatus 10 described above. In this embodiment, the apparatus includes a supplementary light source 200 adjacent each tube 42. Accordingly, each tube 42 (or combination of tubes constituting a single light source 42) is referred to as a primary light source. Each supplementary light source 200 is also in the form of a fluorescent tube. 15 Each supplementary light source 200 and corresponding primary light source 42 are aligned with each other so as to lie in a general plane which is substantially parallel to the general plane in which the window 14 extends. Between each supplementary light source 200 and the corresponding primary light 20 source 42 there is provided a supplementary reflector 201. Each supplementary reflector 201 is wedge-shaped, tapering in a direction from the respective primary light source 42 towards the corresponding supplementary light source 200, as shown in Figure 9. 25 Each supplementary reflector 201 is made up of two plates 202 and 203 which are each bent into three panels 204, 205 and 206, the panels 204 of the two plates being glued to each other to assemble the supplementary reflector 201. All of the outer surfaces of the supplementary reflector 201 are reflective. 30 In this embodiment, the spacers 70 on which the baffle reflector plates 64 are supported are in the form of spaced-apart acrylic blocks. The supplementary reflectors 201 are supported on similar blocks 207.

19 This embodiment includes aluminium extrusions 208, which include the side walls 6 and ledges 10. The back reflectors 76 are each made up of a metal sheet 209 that has been bent to form panels 210, 211, 212, 213 and 214. The panels 211, 212 and 213 5 serve the primary function of the back reflectors 76. There are black strips 215 on the inner surface of the translucent sheet 18, aligned with the baffle reflectors 64, the strips 215 corresponding to the strips 112 described above. 10 It will be appreciated that the back reflectors 76 extends partially around the secondary light sources 200 rather than around the primary light sources 42 as in the embodiments described above. 15 The shape of the supplementary reflectors 201 is such that light from the secondary light sources 200 is transmitted and reflected towards the window 14, and towards the back wall 8 from where it is also reflected towards the window. However, the supplementary reflectors 201 shield, from the primary light sources 42, the light which emanates from the secondary light sources 200. On the other hand, light from the 20 primary light sources 42 that is transmitted towards the secondary light sources 200 is reflected back by the panels 206 of the supplementary reflectors 201. The combination of the light emanating from the primary and secondary light sources 42 and 200 assists in providing greatly enhanced lighting by the arrangement 2 of 25 Figure 9. It will be appreciated that the invention does not rely on elements such as matrices of dots or other arrays (which may be found in certain of the prior art) for providing an even distribution of light through the window. Such elements, apart from providing 30 for a more even distribution of light, could also serve to inhibit the overall amount of light transmitted. Accordingly, the features of the present invention assist it to achieve a desirably even distribution of light while not requiring an unduly powerful source of 20 light to compensate for such an inhibition of light. Embodiments of the invention therefore provide for enhanced efficiency of operation. Additionally, the structure of embodiments of the invention avoids the need for a 5 heavy screen, such as of acrylic, which provides for the transmission of light along its central plane, from light sources located at the edges of the screen, as may be found in the prior art. Thus, such embodiments provide for a construction that is not undesirably heavy. 10 A further advantage of an embodiment of the present invention is that the relatively large surface area of the sheet 54, as a result of its curved shape, provides for effective distribution of the reflected light. In addition, the fact that the light from the tubes 42 is transmitted to the sheet 54 through air in the chamber 16, as opposed to being transmitted, for example, along the cental plane of an acrylic screen as referred to 15 above, provides for relative efficiency in light transmission. This is because light transmission media, made of materials such as acrylic, are not efficient transmitters of light. As a result, the invention also allows for a suitably large arrangement 2, that is, an arrangement having a suitably large window (and hence one which, in an appropriate embodiment, is able to accommodate a large sign without necessitating 20 significantly more powerful light sources). Although the invention is described above in relation to specific embodiments, it will be appreciated by those skilled in the art that the invention is not limited to those embodiments, and may be embodied in many other forms.

Claims

1. An apparatus for producing substantially uniform illumination through a window of a lighting device with side walls and a back wall opposing the window, 5 comprising: a means for lighting within the lighting device; a means for reflecting back-light from a side of the lighting means generally towards an opposing side of the lighting means; a means for diffusing light by reflecting a first fraction of the light generally 10 towards the window and for refracting a second fraction of the light through the diffusing means and generally towards the back wall; and a reflective portion of the inner surface of the back wall, opposing the diffusing means; wherein the reflective portion of the back wall reflects back at least a proportion of the 15 second fraction of light generally towards the diffusing means whereby a third fraction of light is refracted through the diffusing means and generally towards the window.

2. An apparatus according to claim 1, wherein the diffusing means includes at least one of a reflecting means, a plurality of individual planar elements and a sheet. 20

3. An apparatus according to claim 2, wherein the sheet is curved.

4. An apparatus according to claim 3, wherein a concave surface of the curved sheet is closer to the window than an opposing convex surface of the curved sheet. 25

5. An apparatus according to claim 4, wherein a portion of the curved sheet closest to the window is distal to the lighting means, an edge portion of the sheet is proximal to the lighting means and the edge portion is adjacent the back wall. 30

6. An apparatus according to any one of claims 2 to 5, wherein the sheet is, in part at least, one or more of reflective, refractive, transparent and diffusing. 22

7. An apparatus according to claim I or 2, wherein the diffusing means further includes one or more of a single planar sheet, two abutting planar sheets and four triangular sheets configured to form a pyramid. 5

8. An apparatus according to any preceding claim, wherein the diffusing means further includes a plurality of juxtaposed prismatic lenses.

9. An apparatus according to any preceding claim, wherein the lighting means includes at least one light source adjacent a side wall. 10

10. An apparatus according to claim 9, wherein an additional light source and another light source are adjacent opposing side walls.

11. An apparatus according to claim 9 or 10, wherein an intermediate portion of 15 the curved sheet closest to the window is between two opposing light sources.

12. An apparatus according to any one of claims 9 to 11, wherein the curved sheet is positioned in a central portion of the lighting device. 20

13. An apparatus according to any one of claims 9 to 12, wherein the light source is elongate and parallel to a side wall.

14. An apparatus according to any one of claims 9 to 13, wherein the light source is a fluorescent tube. 25

15. An apparatus according to any one of claims 9 to 14, wherein each of four side walls has a respective, adjacent light source.

16. An apparatus according to any one of claims 9 to 15, wherein the light source 30 is a plurality of lights arranged adjacent a side wall. 23

17. An apparatus according to any preceding claim, wherein the back-light reflecting means is positioned between a side wall and a lighting means.

18. An apparatus according to any preceding claim, wherein the position of the 5 lighting means with respect to the back-light reflecting means is adjusted so as to provide substantially uniform illumination through the window.

19. An apparatus according to any preceding claim, wherein the back-light reflecting means is a back reflector. 10

20. An apparatus according to claim 19, wherein the back reflector comprises three or more reflector panels configured to form a back-light reflecting means.

21. An apparatus according to any one of claims 9 to 20, further including at least 15 one of a non-reflective strip and a reflective strip, wherein the non-reflective strip or the reflective strip are positioned substantially parallel to at least one light source.

22. An apparatus according to any preceding claim, further including means for 20 baffle reflecting light from at least one light source generally towards at least one of a central portion of the lighting device, the window and the diffusing means.

23. An apparatus according to claim 22, wherein the baffle reflector means comprises: 25 one or more baffle reflector plates parallel to at least one light source; and a surface closest to the window of at least one baffle reflector plate is substantially reflective.

24. An apparatus according to claim 23, wherein at least one baffle reflector plate 30 has an opposing surface, to the reflective surface, that is substantially non-reflective. 24

25. An apparatus according any preceding claim, wherein the back wall is substantially planar.

26. An apparatus according to any preceding claim, wherein the window is at least 5 one of translucent, transparent, clear, opal coloured, acrylic and an inner frame with an aperture.

27. An apparatus according to any preceding claim, further including: a means for edge reflecting light from a side wall and generally into the 10 lighting device and generally towards the window, wherein the edge reflector means is positioned adjacent any side wall that does not have a lighting means adjacent.

28. An apparatus according to claim 27, wherein the edge reflector means 15 comprises an upper surface, a first front surface and a second front surface configured to reflect light from a side wall and generally into the lighting device and generally towards the window.

29. An apparatus according to claim 28, wherein the first front surface is at an 20 angle of approximately 20 degrees to the second front surface.

30. An apparatus according to any preceding claim, further including an outer frame adapted for securing a translucent sign to the window with an inner frame. 25

31. An apparatus according to any one of claims 9 to 30, wherein an additional light source is adjacent and parallel to another light source.

32. An apparatus according to claim 31, further including a supplementary reflector positioned between the additional light source and the another light source. 30

33. An apparatus for producing substantially uniform illumination through a window of a lighting device as substantially described herein. 25

34. A method for producing substantially uniform illumination through a window of a lighting device comprising the steps of: (a) providing a lighting device enclosure with side walls, a back wall and the 5 window opposing the back wall; (b) providing a light source proximal a side wall; (c) reflecting light from a portion of the light source proximal the side wall generally towards an opposing side of the light source; (d) diffusing the light for substantially uniform illumination of the window by 10 further steps of: (i) providing a diffusing sheet which reflects a first fraction of light generally towards the window and refracts a second fraction of light through the diffusing sheet and generally towards the back wall; (ii) reflecting at least a first proportion of light between the diffusing 15 sheet and the back wall adjacent the diffusing sheet; and (iii) refracting at least a second proportion of light, reflected from the back wall, through the diffusing sheet and generally towards the window. 20

35. A method according to claim 34, further including repeating steps (ii) and (iii) at least twice with successive proportions of light.

36. A method according to claim 34 or 35, further including a step after step (iii) of at least one of multiple reflections and multiple refractions of light between two or 25 more steps of (c), (d)(i), (d)(ii) and (d)(iii).

37. A method according to any one of claims 34 to 36, further including the step of: positioning the diffusing sheet to further improve the substantially uniform 30 illumination. 26

38. A method according to any one of claims 34 to 37, further including the step of: curving the diffusing sheet to further improve the substantially uniform illumination. 5

39. A method according to claim 38, further including the step of: curving and positioning the diffusing sheet such that a concave surface of the sheet is closest to the window. 10

40. A method according to any preceding claim, further including: providing a diffusing surface or at least a diffusing portion to the diffusing sheet; and selecting the diffusing surface or diffusing portion to perform at least one of reflecting light and refracting light, for substantially uniform illumination of 15 the window.

41. A method according to claim 40, further including providing the diffusing surface or diffusing portion of the diffusing sheet with a plurality ofjuxtaposed prismatic lenses. 20

42. A method according to any one of claims 34 to 41, further including providing at least one additional light source proximal a side wall.

43. A method according to claim 42, further including a step of: 25 positioning the at least one additional light source to an opposing side wall to another light source.

44. A method according to any preceding claim, further including a step after step (c) of: 30 adjusting the reflecting of light at step (c) to produce substantially uniform illumination through the window. 27

45. A method according to any preceding claim, further including a step after step (a) of: forming the back wall so that the back wall is substantially planar. 5

46. An apparatus for producing substantially uniform illumination through a window of a lighting device as produced by the method of any one of claims 34 to 45.

47. A method for producing substantially uniform illumination through a window of a lighting device as substantially described herein. 10