WO1999041543A1 - An edge-lit illumination system - Google Patents

An edge-lit illumination system Download PDF

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Publication number
WO1999041543A1
WO1999041543A1 PCT/GB1999/000493 GB9900493W WO9941543A1 WO 1999041543 A1 WO1999041543 A1 WO 1999041543A1 GB 9900493 W GB9900493 W GB 9900493W WO 9941543 A1 WO9941543 A1 WO 9941543A1
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WO
WIPO (PCT)
Prior art keywords
sheet
edge
light transmitting
light
transmitting sheet
Prior art date
Application number
PCT/GB1999/000493
Other languages
French (fr)
Inventor
John Henry Forster
John Mark Page
Heather Allinson
Original Assignee
Ineos Acrylics Uk Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GBGB9803327.7A priority Critical patent/GB9803327D0/en
Priority to GB9803327.7 priority
Application filed by Ineos Acrylics Uk Limited filed Critical Ineos Acrylics Uk Limited
Publication of WO1999041543A1 publication Critical patent/WO1999041543A1/en

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Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B6/00Light guides
    • G02B6/0001Light guides specially adapted for lighting devices or systems
    • G02B6/0011Light guides specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033Means for improving the coupling-out of light from the light guide
    • G02B6/005Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055Reflecting element, sheet or layer
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B6/00Light guides
    • G02B6/0001Light guides specially adapted for lighting devices or systems
    • G02B6/0011Light guides specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0023Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
    • G02B6/003Lens or lenticular sheet or layer

Abstract

An edge-lit illumination system comprising a light transmitting sheet (13) and a light source (10) is claimed. The light source (10) is positioned in proximity to and adjacent to the light transmitting sheet (13) which has a matrix of etched, painted or screen printed dots covering at least 50 % of at least one of its opposing surfaces. The edge-lit illumination system further comprises a reflective backing material (12) which is spaced apart from and faces one surface of the light transmitting sheet (13) such that it substantially overlies this surface. This system provides for an overall increase in average light intensity from the light transmitting sheet (13) as compared to a system where the reflective backing material is touching the surface of the light transmitting sheet.

Description

An edge-lit illumination system

The present invention relates to an edge-lit illumination system. Edge-lit illumination systems which have as a basic feature a light source positioned alongside an edge of a light transmitting sheet are well known. The light transmitting sheet may be treated on one or both of it's surfaces which means that the light entering the edge of this sheet is irregularly reflected or scattered. Therefore the sheet transmits more light than would be expected from the intensity of the light source. Also this light is spread more evenly across the illuminated surface. Examples of such edge-lit illumination systems are EP- A- 0549679 where the light transmitting sheet is an acrylic resin having a matrix of dots applied to substantially all of both surfaces. In one particular embodiment the density of the dot matrix increases in a direction along the light transmitting sheet away from the light source. US-A- 5,178,447 discloses an edge- t light transmitting sheet with an irregular mesh pattern, formed on one of its surfaces, comprising dots of light reflecting material which increase in density in a direction along the sheet away from the light source characterised in that the edge of the sheet through which the light enters is deliberately roughened. US-4,385,343 discloses an edge-lit illumination system where both surfaces of the light transmitting sheet are roughened, preferably in a manner so as to have myriad facets randomly disposed.

Within the basic structure of such edge-lit illuminated systems a reflective backing material may be positioned in contact with at least one of the opposing surfaces of this light transmitting sheet. The backing material is usually of similar physical dimensions to this sheet and placed in contact with it.

It is an object of the present invention to provide such an edge-lit illumination system with a further enhancement in illumination.

Accordingly the present invention provides an edge-lit illumination system comprising a light transmitting sheet and a light source; the light being positioned in proximity to and adjacent to an edge of said light transmitting sheet, said light transmitting sheet having a matrix of etched, painted or screen printed dots covering at least 30% of at least one of its opposing surfaces, and further comprising a reflective backing material wherein said reflective backing material is spaced apart from and faces one surface of said light transmitting sheet such that it substantially overlies said surface.

This invention gives an increase in the overall average output of light intensity from the light transmitting sheet. By average overall intensity we mean an average of light intensity readings measured in Lux at various points across the light transmitting sheet.

The light transmitting sheet is a transparent material. It may be glass or plastic but is preferably plastic and more specifically a clear acrylic sheet. The surface of at least one side of this sheet is treated with a matrix of etched, painted or screen printed dots, substantially covering at least 50% of the surface. The matrix is defined as a continuous pattern of discrete dots and such pattern may be random. The preferred method of treatment is via screen printing. Preferably the coverage of the matrix of dots is at least 50% and more preferably at least 65% of the surface. When the coverage of the surface with the dot matrix is not substantially all of the surface a part of the surface which is free from the dot matrix may be an area on the surface of the sheet adjacent to the light source extending along the whole edge of the sheet adjacent to the light source. Hence for a dual light source edge-lit sheet there may be two such areas, each at the edge of the sheet adjacent to a light source. In another example at least 90% of the surface may be covered and alternatively substantially all of the surface may be covered with the dot matrix. Preferably both opposing surfaces are so treated.

The dots within the matrix may be of any shape, for example square, round, rectangular, triangular or irregular, for example irregularly shaped generally elongated structures based on squares and/or rectangles. They can be translucent or opaque and are preferably light coloured . By translucent we mean capable of transmitting rays of light with diffusion also. By opaque we mean substantially incapable of transmitting light. Preferably the density of dots is increased in a direction away from the edge of the light transmitting sheet at which the light source is positioned. The density of dots can be increased by increasing the number of dots per unit area and decreasing the spacing between the dots or by keeping the spacing between the dots the same and increasing the size of the dots. Within the matrix the level of coverage for the dots, for example as ink coverage if treatment of the surface is by screen printing, increases from between 0 to 9%, at the edge of the matrix closest to the light source, up to between 10 to 70% at a distance from the edge. More preferably the level of ink coverage ranges from between 0 to 5% to between 10 to 40% and specifically from between 0 to 4% to between 10 to 20%. Alternatively the level of ink coverage may be uniform across the sheet. 10% coverage means that if the whole sheet were covered with a uniform dot matrix then 10% of the total surface area would be covered with ink.

Many types of light source are available but preferably fluorescent tubing is used. The distance from the edge of the light transmitting panel to the crest of the tube is preferably between 1 and 2 mm. The diameter of the tube, D, may vary from typically 6mm, commonly referred to as T2 to 25mm, commonly referred to as T8. Preferably the fluorescent tube is an aperture tube. This type of tube has coated on the inside wall of the glass a reflective coating with a fluorescent coating on top of it. The aperture tube opening is a slot, for example 30 degrees, with no coating that runs the length of the tube and this clear slot is arranged so it is directing light from the light source at the edge of the light transmitting sheet. The light path length is preferably 1.5D to 100D and more specifically 20.5D to 100D. By light path length we mean for a single light source the furthest distance, along the length of the surface of one side of this sheet, through which light is emitted. For two light sources, adjacent to opposite edges of this sheet, then the light path length is half the distance between the two tubes. Where the light source is at least one fluorescent tube a reflector is typically positioned behind each fluorescent tube and may be any material capable of reflecting light, for example mirrored aluminium. Preferably the light source is in a fixed relationship to the light transmitting sheet.

The reflective backing material may be paper, metal or plastic but is preferably metal or plastic. For example gloss white coated aluminium, styrene, dense white Acrylic gloss sheet (opaque white 1209 available ex Imperial Chemical Industries PLC). The spacing between the reflective backing material and light transmitting sheet is at least 1mm and preferably at least 4mm. It is preferably a constant spacing between the reflective backing material and the light transmitting sheet. The spacing is preferably solely an air gap. The backing material may be held at a constant distance from the light transmitting sheet by spacers at the edges of the backing material or more preferably by a supporting frame around the whole illumination system. The depth of such a frame may be a limiting factor on the maximum spacing achievable between the sheet and the backing gap.

A second light transmitting sheet may be positioned substantially in contact with or spaced apart from the reflective backing material parallel and co-extensive to the opposing surface of the reflective backing material to that of the light transmitting sheet so as to give two sided illumination from the edge-lit system.

Within the basic structure of this edge-lit illuminated system, a diffuser may be positioned substantially in contact with or spaced apart from ail of the opposing surface of the light transmitting sheet to that of the reflective backing sheet, for example in a single sided sign where the desired artwork would be positioned on the surface of the diffuser. The diffuser may be translucent or transparent and may be glass or plastic material. Preferably the diffuser is capable of transmitting as much light as possible with some diffusion capabilities also. For example 3mm thickness cast acrylic opal 040 sheet (available ex Imperial Chemical Industries PLC) which has a light transmittance value of 46% or more preferably 3mm thickness 000 clear silk cast acrylic sheet (available ex Imperial Chemical Industries PLC) having a light transmittance of 79% rather than 000 clear cast acrylic sheet (available ex Imperial Chemical Industries PLC) which has a light transmittance of 93%.

The illumination system may be surrounded by a supporting frame. The dimensions of the frame should be sufficient to house the light source(s), electrical and controlling equipment, if present within the frame, and be of sufficient depth to enclose the combined thickness of the light transmitting sheet, diffuser(s) and reflective backing material, if present. The electrical and control equipment may be situated beside or behind the light source. In the latter case the depth of the frame may be slightly increased but the width of the frame may be narrower. This may be preferred in some signing applications because the visible area of the 5 artwork can be made larger whilst the size of the sign remains the same.

Edge-lit illuminated display systems described in the present invention can be used as lighting devices or light sources as well as advertising displays and also may be modified for use as illuminated shelving.

Specific embodiments of the invention will now be further described in the following

10 examples and with reference to the accompanying drawings (Figures 1 and 2) which represent a section through an illuminated display system according to the invention. Example 1

In Figure 1 the light transmitting sheet (13) is a rectangular (450mm sheet width by 610mm length ( by length we mean the side of the sheet parallel and adjacent to the light source))

15 10mm thickness clear cast polymethylmethacrylate sheet which has been treated by screen printing a matrix of white dots directly on to both its opposing surfaces (17 and 18). In this case the matrix covers substantially all of both surfaces and within the matrix the level of ink coverage ranges from about 3% increasing to 16% along the light path length, 225mm (9D), away from each of two fluorescent tube light sources. These are two Sylvania Luxline Plus

20 Daylight Delux fluorescent tubes (10) each of which have a power output of 18 Watts, a colour rendering value (Ra) of 86 ,a colour temperature of 6500 Kelvin and a diameter of 25mm. Each one is positioned adjacent to one of two parallel edges of the light transmitting sheet surrounded by a mirrored aluminium reflector (11 ). The diffuser (15) is a 3mm thickness cast acrylic Opal 040 sheet having a light transmittance of 46% which is placed in contact with the

25 surface of the light transmitting sheet (13) to which artwork (19) is applied. The backing material (12) is gloss white sprayed aluminium. The illuminated system is housed in a frame (16) with a window (14).

The overall average output of light intensity from the light transmitting sheet is measured as follows: A light meter (RS component part number 1807133) set to F (fluorescent) is used to

30 measure the light intensity (units of Lux) across the light transmitting sheet. The meter is hand held, with the measuring head attached to the meter via a flexible cord, and the sensor has a diameter of approximately 50mm. 9 light readings were taken across the sheet by placing the meter head on the window (14). These were 3 sets of 3 readings taken, one set consisting of a reading taken near the top left hand side of the light transmitting sheet adjacent to one

35 fluorescent tube, in the top middle of the sheet and near the top right hand side of the light transmitting sheet adjacent to the other fluorescent tube. This was then repeated for the middle of the sheet and the bottom of the sheet. Each set of 3 readings was averaged and then all of these readings were averaged to give one average value for the whole light transmitting sheet. Tables 1. 2. and 3 show the 9 readings taken across the sheet for Omm, 5mm and 10mm spacings between the light transmitting sheet (13) and the reflective backing material (12). Table 4 shows the overall average output of light intensity values obtained for varying the size of the spacing.

Table 1 - Comparative

Light Intensities across the sheet Avg Light intensity in Lux in Lux

Omm Spacing Left Middle Right

Top 850 860 880 863

Middle 1600 1465 1750 1605

Bottom 930 900 930 920

Table 2

Light Intensities across the sheet Avg Light intensity in Lux in Lux

5mm Spacing Left Middle Right

Top 1265 948 1175 1129

Middle 2410 1565 2075 2017

Figure imgf000007_0001
Bottom 1312 957 1192 1154

Table 3

Light Intensities across the sheet Avg Light intensity in Lux in Lux

10mm Spacing Left Middle Right

Top 1433 980 1500 1304

Middle 3000 1600 2465 2415

Figure imgf000007_0002
Bottom 1690 1050 1520 1420 Table 4

Size of Spacing Average Sheet Light Intensity in mm in Lux

O(Comparative) 3291

5 4300

10 5139

Figure imgf000008_0001
Example 2

This was a similar experiment to Example 1 except the diffuser material was changed to 3mm 10000 clear silk cast acrylic sheet with a light transmittance of 79% . Tables 5 and 6 show the 9 readings taken across the sheet for Omm and 5mm spacings between the light transmitting sheet (13) and the reflective backing material (12). Table 7 shows the overall average output of light intensity values obtained for varying the size of the spacing.

Table 5 - Comparative

15 Light Intensities across the sheet Avg Light intensity in Lux in Lux

Omm Spacing Left Middle Right

Top 1100 1104 1180 1128

Middle 2090 1970 2345 2135

20

Figure imgf000008_0002
Bottom 1178 1182 1335 1232

Table 6

Light Intensities across the sheet Avg Light intensity in Lux in Lux

5mm Spacing Left Middle Right

25 Top 1350 1170 1580 1367

Middle 2840 1955 3045 2613

Bottom 1870 1355 1690 1638

Table 7

Size of Spacing Average Sheet Light Intensity

30 in mm in Lux

O(Comparative) 4495

Figure imgf000008_0003
Example 3

This was a similar experiment to Example 1 except the light source was changed to two Philips TLD' fluorescent tubes which each have a clear open aperture window of 30 degrees, a power output of 18 Watts, a colour rendering value (Ra) of 86, a colour temperature of 6500 Kelvin and a diameter of 25mm Tables 8 and 9 show the 9 readings taken across the sheet for Omm and 10mm spacings between the light transmitting sheet (13) and the reflective backing material (12). Table 10 shows the overall average output of light intensity values obtained for varying the size of the spacing

Table 8 - Comparative

Light I ntensities across the sheet Avg Light intensity in Lux in Lux

Omm Spacing Left Middle Right

Top 1350 1400 1350 1367

Middle 2710 1650 3060 2807

Figure imgf000009_0001
Bottom 1500 1560 1775 1612

Table 9

Light Intensities across the sheet Avg Light intensity in Lux in Lux

10mm Spacing Left Middle Right

Top 2345 1285 1867 1832

Middle 4940 1970 4185 3748

Bottom 2700 1410 2065 2058

Table 10

Size of Spacing Average Sheet Light Intensity in mm in Lux

0 (Comparative) 5786

Figure imgf000009_0002
10 7638

In all of the above 3 Examples an increase in overall illumination has been demonstrated for moving the reflective backing gap away from the light transmitting sheet. The increase is not totally even across the sheet as shown in Tables 1 , 2, 3, 5, 6, 8 and 9 but is at a slightly higher value where the light transmitting sheet is adjacent to each of the fluorescent tubes. Example 4

This Example differs from Example 3 in that the light transmitting sheet dimensions are 450mm by 620mm. In this case the matrix of dots covers substantially all of both surfaces and within the matrix the level of ink coverage ranges from 0% increasing to 16% along the light path 5 length, 225mm (9D), away from each of two fluorescent tube light sources. There is no diffuser present for this Example. The backing reflector gap is 7mm. The overall average output of light intensity from the light transmitting sheet is measured using the light meter as described in Example 1. 15 light readings were taken across the sheet by placing the meter head on the window (14). These were 5 sets of 3 readings taken, one set consisting of a reading taken

10 65mm along the light path length from the top left hand side of the light transmitting sheet adjacent to the fluorescent tube followed by a reading for the middle of the sheet and one for the bottom of the sheet. 4 further sets of 3 readings were taken at 145, 225, 305 and 385mm respectively along the light path length. Each set of 3 readings was averaged across the light transmitting sheet and the data is displayed in Table 11 as A. Also shown is data B using a dot

15 pattern as described in Examples 1 , 2 and 3 and comparative data C using a dot pattern as described in Examples 1 , 2 and 3 with no spacing between the reflective backing material and the light transmitting sheet .

Table 11

Light Intensities across the sheet Avg Light Intensity

20 in Lux in Lux

65mm 145mm 225mm 305mm 385mm

A 3053 3206 3286 3117 2939 3120

B 4453 3283 2955 3090 4327 3622

C (Comp) 1827 1458 1406 1523 1897 1622

25 It can be seen by comparing A to C there is an increase in the overall illumination from the sheet by spacing the reflective backing material apart form the light transmitting sheet. It can be further seen by comparing A to B that a reduction in the ink coverage of the dot matrix at the edges of the sheet adjacent to each of these tubes shows that the overall increase in illumination is more even across the light transmitting sheet if so required.

30 Example 5

This Example differs from Example 4 in that a defined area on the surface of the sheet starting at the edge of the sheet adjacent to each light source is free of the dot matrix. The length of such an area is the full length of the side of the sheet adjacent to the light source. In this case the two areas are 60mm by 620mm, i.e. 27% of the sheet is free of the dot matrix. Table 12 shows this data as D with data B and comparative data C as in Example 5.

Table 12

Light Intensities across the sheet Avg Light Intensity in Lux in Lux

65mm 145mm 225mm 305mm 385mm

D 2834 3467 3258 3556 3102 3243

B 4453 3283 2955 3090 4327 3622

Figure imgf000011_0001
C (Comp) 1827 1458 1406 1523 1897 1622

It can be seen by comparing D to C there is an increase in the overall illumination from the sheet by spacing the reflective backing material apart form the light transmitting sheet. It can be further seen by comparing D to B that having an area free from the dot matrix at the edges of the sheet adjacent to each of these fluorescent tubes illustrates that the overall increase in illumination is more even across the light transmitting sheet.

Example 6

In Figure 2 the light transmitting sheet (20) is a rectangular (600mm sheet width by 350mm length ( by length we mean the side of the sheet parallel and adjacent to the light source)) 8mm thickness clear cast polymethylmethacrylate sheet which has been treated by screen printing a matrix of white dots directly on to both its opposing surfaces (21 and 22). In this case the matrix covers substantially all of both surfaces and within the matrix the level of ink coverage ranges from about 2.8% increasing to 11% along the light path length, 600mm (24D), away from the single light source fluorescent tube (23) which is as defined in Example 1. The diffuser (24), artwork (25), reflective backing material (26), frame (27) and window (28) are as defined in Example 1.

The overall average output of light intensity from the light transmitting sheet is measured using the light meter as described in Example 1. 21 light readings were taken across the sheet by placing the meter head on the window (14). These were 7 sets of 3 readings taken, one set consisting of a reading taken 70mm along the light path length from the top left hand side of the light transmitting sheet adjacent to the fluorescent tube followed by a reading for the middle of the sheet and one for the bottom of the sheet. 6 further sets of 3 readings were taken at 150, 230, 310, 380, 460 and 540mm respectively along the light path length. Each set of 3 10

readings was averaged across the light transmitting sheet and the data is displayed in Table 13.

Table 13

Spacing Light Intensities across the sheet Sheet Light 5 in mm in Lux Intensity in Lux

70mm 150mm 230mm 310mm 380mm 460mm 540mm

0 (Comp)72 58 56 51 50 48 49 384

1 79 63 60 55 54 53 54 419 5 82 69 65 59 57 56 57 444

10 10 80 66 62 55 54 53 55 425

This Table shows an overall increase in illumination for various levels of spacing between the light transmitting sheet and the reflective backing material as compared to no spacing.

Claims

11Claims
1. An edge-lit illumination system comprising a light transmitting sheet and a light source; the light being positioned in proximity to and adjacent to an edge of said light transmitting sheet, said light transmitting sheet having a matrix of etched, painted or screen
5 printed dots covering at least 30% of at least one of its opposing surfaces, and further comprising a reflective backing material wherein said reflective backing material is spaced apart from and faces one surface of said light transmitting sheet such that it substantially overlies said surface.
2. An edge-lit illumination system as claimed in claim 1 wherein the density of dots
10 within the matrix is increased in a direction away from the edge of the light transmitting sheet at which the light source is positioned
3. An edge-lit illumination system as claimed in either claim 1 or 2 wherein a second light transmitting sheet is positioned in contact with substantially all of the opposing surface of the light transmitting sheet to that of the reflective backing sheet.
154. An edge-lit illumination system as claimed in claim 3 wherein the second light transmitting sheet is positioned spaced apart from the reflective backing material parallel and co-extensive to the opposing surface of the reflective backing material to that of the light transmitting sheet.
5. An edge-lit illumination system as claimed in any of claims 1 to 4 wherein the 20 matrix of dots covers at least 65% of at least one of its opposing surfaces of the light transmitting sheet.
6. An edge-lit illumination system as claimed in any of claims 1 to 4 wherein the matrix of dots covers substantially all of at least one of its opposing surfaces of the light transmitting sheet.
257. An edge-lit illumination system as claimed in any of claims 1 to 6 wherein a part of the surface which is free from the dot matrix is an area on the surface of the sheet adjacent to the light source extending along the whole edge of the sheet adjacent to the light source.
8. An edge-lit illumination system as claimed in any of claims 1 to 7 wherein the spacing between the or each light transmitting sheet and the reflective backing material is at
30 least 1 millimetre.
9. An edge-lit illumination system as claimed in any of claims 1 to 8 wherein the spacing between the or each light transmitting sheet and the reflective backing material is at least 4 millimetres . 12
10. An edge-lit illumination system as claimed in any of claims 1 to 9 wherein the light source is a fluorescent tube and the light path length is 1.5 to 100 times the diameter of said fluorescent tube.
11. An edge-lit illumination system as claimed in claim 10 wherein the light path length is 520.5 to 100 times the diameter of the fluorescent tube.
PCT/GB1999/000493 1998-02-17 1999-02-15 An edge-lit illumination system WO1999041543A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GBGB9803327.7A GB9803327D0 (en) 1998-02-17 1998-02-17 An edge-lit illumination system
GB9803327.7 1998-02-17

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AU25372/99A AU2537299A (en) 1998-02-17 1999-02-15 An edge-lit illumination system

Publications (1)

Publication Number Publication Date
WO1999041543A1 true WO1999041543A1 (en) 1999-08-19

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ID=10827126

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Country Status (4)

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GB (1) GB9803327D0 (en)
WO (1) WO1999041543A1 (en)
ZA (1) ZA9901238B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005016081A1 (en) * 2003-08-13 2005-02-24 Stephen Neal Picture frame with illumination

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4385343A (en) 1978-12-26 1983-05-24 Plumly George W Edge lighted devices
US5178447A (en) 1990-06-26 1993-01-12 Kabushiki Kaisha Meitaku Shisutemu Edge light panel
EP0549679A1 (en) 1990-09-20 1993-07-07 Illumination Research Group Pr A display system.
EP0719981A1 (en) * 1994-12-26 1996-07-03 Stanley Electric Co., Ltd. Flat lighting device
EP0750209A1 (en) * 1995-06-22 1996-12-27 International Business Machines Corporation Light guiding sheet and manufacturing method thereof
EP0800036A1 (en) * 1996-04-04 1997-10-08 Hitachi Cable, Ltd. Lighting system
EP0864905A2 (en) * 1997-02-18 1998-09-16 Dai Nippon Printing Co., Ltd. Backlight device and liquid crystal display device

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4385343A (en) 1978-12-26 1983-05-24 Plumly George W Edge lighted devices
US5178447A (en) 1990-06-26 1993-01-12 Kabushiki Kaisha Meitaku Shisutemu Edge light panel
EP0549679A1 (en) 1990-09-20 1993-07-07 Illumination Research Group Pr A display system.
EP0719981A1 (en) * 1994-12-26 1996-07-03 Stanley Electric Co., Ltd. Flat lighting device
EP0750209A1 (en) * 1995-06-22 1996-12-27 International Business Machines Corporation Light guiding sheet and manufacturing method thereof
EP0800036A1 (en) * 1996-04-04 1997-10-08 Hitachi Cable, Ltd. Lighting system
EP0864905A2 (en) * 1997-02-18 1998-09-16 Dai Nippon Printing Co., Ltd. Backlight device and liquid crystal display device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005016081A1 (en) * 2003-08-13 2005-02-24 Stephen Neal Picture frame with illumination

Also Published As

Publication number Publication date
GB9803327D0 (en) 1998-04-15
AU2537299A (en) 1999-08-30
ZA9901238B (en) 1999-08-17

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