WO1997015939A2 - Electroluminescent light source - Google Patents
Electroluminescent light source Download PDFInfo
- Publication number
- WO1997015939A2 WO1997015939A2 PCT/IL1996/000130 IL9600130W WO9715939A2 WO 1997015939 A2 WO1997015939 A2 WO 1997015939A2 IL 9600130 W IL9600130 W IL 9600130W WO 9715939 A2 WO9715939 A2 WO 9715939A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- light source
- layer
- transparent
- electrode
- mixture
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/20—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the material in which the electroluminescent material is embedded
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/10—Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/26—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode
Definitions
- the present invention relates to an electroluminescent (EL) light source. More particularly, it relates to a flexible, cable-like light source — an electroluminescent filament (ELF) — and to a method for producing same.
- EL electroluminescent
- Such sources in which an electroluminophor powder is located in an electric field created between two or more electrodes, are known.
- all of these devices suffer from a fundamental disadvantage which is inherent in the method of preparation of all cable-like EL sources: as the EL layer is applied to the cable core (whether conductive or insulating) by a continuous process of dip- coating, the EL particle/binder mixture must be a liquid of a fairly low viscosity, which is achieved by adding a suitable solvent. Yet once the EL layer is applied, this solvent, as is the way of solvents, evaporates and leaves behind a layer that is full of air-containing pores. These pores greatly reduce the electrical capacity of the EL sources and. thereby, their brightness.
- a further drawback of the prior art EL sources resides in the fact that the above-mentioned air-filled pores constitute an optical discontinuity in the EL layer, causing further, substantial light losses due to total internal reflection at the binder/air interface, as well as through dispersion by the irregular wall surfaces of these air bubbles. Disclosure of the Invention
- a light source consisting of at least one flexible, cable-like electroluminescent filament, each filament comprising a central electrode surrounded by an electrically insulating dielectric layer; a layer consisting of a mixture of an electroluminophor powder and a binder, said mixture being applied to said dielectric layer; a transparent electrode surrounding the layer consisting of said mixture, wherein pores formed in said mixture layer are filled in by a transparent filler substance.
- the invention further provides a method for preparing a light source, comprising the steps of covering a central electrode with an electrically insulating, dielectric layer: applying a mixture of an electroluminophor powder and a binder to said central electrode as covered by said dielectric layer; applying a transparent electrode to said mixture layer; impregnating said mixture layer, through said transparent electrode, with a filler substance to fill in pores in said mixture layer; covering said transparent electrode with a barrier layer to prevent said filler substance from seeping out of said filled-in pores or from evaporating therefrom, and covering said barrier layer with a layer of a flexible, transparent polymer.
- Fig. 1 is a longitudinal cross-section of a first embodiment of an ELF having two electrodes
- Fig. 2 represents a similar cross-section of another embodiment of an ELF which has an additional electrode
- Fig. 3 is a longitudinal cross-section, enlarged relative to Figs. 1 and 2, which illustrates the detailed structure of the EL layer, including the pores
- Fig. 4 shows, in its left half, the pores of Fig. 3 filled with a fluid monomer, and in the right half, the pores in which the monomer has been polymerized into its solid state by being exposed to UV radiation
- Fig. 5 illustrates an embodiment of the ELF suitable for attachment to flat surfaces
- Fig. 6 is an embodiment which, further to the additional electrode of Fig. 2.
- Fig. 7 is a view in cross-section along plane VII-VII of the ELF of Fig. 6;
- Fig. 8 illustrates a light-emitting filament with several electrodes;
- Fig. 9 is a cross-sectional view of an embodiment with two light-emitting filaments;
- Fig. 10 is a longitudinal cross-section of the same embodiment along plane X-X of Fig. 9;
- Fig. 1 1 shows an embodiment similar to the embodiment of Fig. 2, in which the electrical contact between the transparent electrode and the additional electrode has been enhanced by application of conductive droplets, and
- Fig. 7 is a view in cross-section along plane VII-VII of the ELF of Fig. 6;
- Fig. 8 illustrates a light-emitting filament with several electrodes;
- Fig. 9 is a cross-sectional view of an embodiment with two light-emitting filaments;
- Fig. 10 is a longitudinal cross-section of the same embodiment along plane X-X of Fig.
- FIG. 12 illustrates a similar application of conductive droplets to the transparent electrodes ofthe embodiment of Fig. 9.
- Fig. 1 a first embodiment of an ELF comprising a flexible copper wire serving as an electrode 2, and covered by an electrically insulating dielectric layer 4 advantageously consisting of BaTiO, powder in a flexible binder on the basis of cyanoethyl starch.
- Layer 4 is preferably of a thickness of 10-15 ⁇ m.
- the electroluminophor layer 6 in a flexible binder on the basis of cyanoethyl starch.
- Layer 6 which preferably has a thickness of 30 to 100 ⁇ m, is surrounded by a thin, transparent electrode 8, e.g., a gold layer of a thickness of 200-400 A. Conductive oxides or conductive polymers are also suitable. Layer 6, in its tum. is covered by a barrier layer 10 consisting of a transparent viscous substance, e.g.. a silicon fluid or grease of a viscosity exceeding 1000 mPa sec. The purpose of barrier layer 10 will be explained further below. Layer 10 is surrounded a transparent, flexible polymer layer 12. e.g.. polyethylene or PVC. of a thickness of 0.3- 1.2 mm.
- a transparent viscous substance e.g. a silicon fluid or grease of a viscosity exceeding 1000 mPa sec.
- barrier layer 10 is surrounded a transparent, flexible polymer layer 12. e.g.. polyethylene or PVC. of a thickness of 0.3- 1.2 mm.
- Fig. 2 differs from that of Fig. 1 in that it possesses an additional electrode 14 in the form of a copper wire of a thickness of, e.g.. 0.08 mm, helically wound around the surface of transparent electrode 8 to equalize the potential along the relatively high-resistance electrode 8 and to ensure continuous light emission along the entire ELF, even if the thin electrode 8 should break.
- the ELF of Fig. 2 emits light at the application of an appropriate AC voltage between electrodes 2 and 14.
- Fig. 3 enlarged relative to Figs. 1 and 2, shows the detailed structure of EL layer 6.
- the mixture of EL particles 16 and binder 18 (cyanoethyl starch or cyanoethyl cellulose with a dielectric constant of ⁇ «24) is a liquid of fairly low viscosity, which is achieved by dissolving binder 18 in a suitable organic solvent, for instance, acetone or DMF.
- a suitable organic solvent for instance, acetone or DMF.
- the pores in layer 6 may have their origin in processes other than the evaporation of solvent, e.g., in certain mixing procedures.
- the transparent electrode 8 on EL layer 6. preferably in the form of a transparent gold layer of a thickness of 200-400 A. which is preferably done by a per se known sputtering process.
- Pores 20 are eliminated at this stage by filling them in. using the capillary effect, with a filler liquid such as ethyl acetate which wets binder 18.
- a filler liquid such as ethyl acetate which wets binder 18.
- This liquid is applied through electrode 8, which, considering its microscopic thickness, is not only transparent, but also liquid-permeable.
- transparent electrode 8 is. in a subsequent stage, covered with barrier layer 10, consisting of a viscous, transparent, dielectric material which does not react chemically with layer 6 and the filler liquid.
- barrier layer 10 consisting of a viscous, transparent, dielectric material which does not react chemically with layer 6 and the filler liquid.
- cyanoethyl selected as binder 18 ethyl acetate may serve as filler substance and silicone oil of a viscosity exceeding 1000 mPa sec as barrier layer 10.
- the brightness of an ELF impregnated with ethyl acetate and covered with a barrier layer 10 of silicone oil is 15-20% higher than that of a non- impregnated ELF, other conditions and parameters being the same.
- the index of refraction of barrier layer 10 should exceed the index of refraction of the external polymer 12, but should be lower than the index of refraction of transparent electrode 8.
- a filler substance that is of low viscosity and easily penetrates pores 20 when hot (at a temperature less than, or equal to, 200°C) and sha ⁇ ly increases its viscosity, or even passes into the solid state when abruptly cooled and/or following special irradiation.
- liquid methyl methacrylate containing methylic ether of benzoin as photoinitiator may be used to fill pores 20 at room temperature. After that, the system is irradiated with UV light of a wavelength of 254 nm. Methyl methacrylate photopolymerization leads to formation of polymethyl-methacrylate.
- the viscosity of the filler substance is sharply increased by several orders, so that the pores remain permanently filled.
- barrier layer 10 while not required for blocking liquid in the pores, is still necessary, since it plays several advantageous roles in increasing ELF reliability:
- this layer prevents friction of the external polymer layer 12 against the thin, transparent electrode 8. thus mechanically protecting electrode 8.
- Barrier layer 10 may be hydrophobic, such as silicone oil, and serve as an additional barrier against water vapor penetration into the electroluminescent layer. It may be hydrophilic, such as glycerin or ethylene glycol, in this case playing the role of a dessicant. In both cases, barrier layer 10 increases ELF service life.
- - Barrier layer 10 allows easy removal of external polymer layer 12 without damaging underlying layers, which is necessary when mating connectors to the ELF.
- Fig. 4 is identical to Fig. 3, but with pores 20 filled with a fluid monomer, while the right half of Fig. 4 shows that, exposed to UV radiation in a subsequent manufacturing step, the monomer is polymerized into its solid state, indicated by the heavy lines 22.
- Fig. 5 illustrates an ELF construction specifically designed for attachment to flat surfaces.
- transparent electrode 8 is applied only on half of the ELF surface to prevent light emission from the back side (not visible to the consumer), thus reducing power consumption.
- the transparent, flexible polymer layer 12 has a special flat portion 23 which facilitates attachment to flat surfaces.
- Layers 4. 6 and 10 have the same function as layers with the same numbers in the other drawings.
- Fig. 6 illustrates an embodiment which, in addition to the thin, helically wound wire electrode 14 of the embodiment of Fig. 2, is also provided with a longitudinally disposed, relatively heavy auxiliary electrode 24 which is in conductive contact with the windings of thin wire electrode 14. Due to the capability of electrode 24 to carry relatively heavy electrical currents, this design facilitates operation of ELFs of lengths of up to 100 m.
- Fig. 7 is a cross-sectional view of the ELF of Fig. 6. showing the pear-like shape of this embodiment.
- the embodiment shown in Fig. 8 has several light- emitting filaments enclosed in the transparent, flexible polymer layer 12. This design is capable of a higher light output compared to the embodiment, say, of Fig. 2. Electrical potential to the transparent electrodes 8 of each of the light-emitting filaments is supplied by a common central electrode 14 which is in contact with the transparent electrodes 8 of the separate filaments. As electrode 14 does not screen off the light, it can have a relatively large diameter that permits operation of very long ELFs.
- Figs. 9 and 10 has two filaments touching each other with their transparent electrodes 8. Except for the area of the contact of layers 8, both filaments are covered by a barrier layer 10 and are enclosed together in polymer layer 12.
- the electrical voltage is supplied between electrodes 2 of the filaments and to achieve a normal level of emission from each of the filaments, twice the voltage is required in this embodiment.
- the main advantage of the embodiment is the possibility of using very long continuous filaments (up to 300 m). Normally, the helically wound thin wire 14 (Figs. 2 to 6) limits the electrical current that can be applied to the filament, thus limiting the length of a continuous filament. In this embodiment, the current flows through the much larger core electrodes 2.
- droplets 26 of a conductive adhesive or a conductive ink are applied to additional electrode 14 during the winding thereof onto transparent electrode 8 at suitable distances from one droplet to the other ( 1 cm-20 cm).
- the conductive droplets, the pu ⁇ ose of which is to improve the long-term electrical contact between electrode 14 and electrode 8. are cured by moving the entire filament through an oven or exposing it to UV radiation.
- a similar advantage is achieved by applying droplets 26 between transparent electrodes 8 in the embodiment of Fig. 12. After application of droplets 26, the filaments are mechanicallly pressed against each other and are subjected to a curing process.
- the electroluminophor used is advantageously a commercially available zinc sulfide doped with copper and/or manganese in various proportions to produce the colours desired.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU72266/96A AU7226696A (en) | 1995-10-26 | 1996-10-23 | Electroluminescent light source |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IL115776 | 1995-10-26 | ||
IL11577695A IL115776A0 (en) | 1995-10-26 | 1995-10-26 | Electroluminescent light source |
Publications (2)
Publication Number | Publication Date |
---|---|
WO1997015939A2 true WO1997015939A2 (en) | 1997-05-01 |
WO1997015939A3 WO1997015939A3 (en) | 1997-07-31 |
Family
ID=11068124
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IL1996/000130 WO1997015939A2 (en) | 1995-10-26 | 1996-10-23 | Electroluminescent light source |
Country Status (3)
Country | Link |
---|---|
AU (1) | AU7226696A (en) |
IL (1) | IL115776A0 (en) |
WO (1) | WO1997015939A2 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5869930A (en) * | 1996-10-22 | 1999-02-09 | Elam-Electroluminescent Industries Ltd. | Electroluminescent light source with a mixture layer filled with a transparent filler substance |
NL1013742C2 (en) * | 1999-12-03 | 2001-06-06 | Mark Kok | System for generating light by means of electroluminescence. |
WO2002098177A1 (en) * | 2001-05-31 | 2002-12-05 | Agfa Gevaert N.V. | System for generating light by means of electroluminescence |
DE10232759A1 (en) * | 2002-07-18 | 2004-03-25 | Martin Eickhoff | Novel products - e.g. clothing, fashion accessories, construction site signs - feature enhanced safety and illuminating function and incorporate electroluminescent (EL) cable(s) |
WO2006069517A1 (en) * | 2004-12-29 | 2006-07-06 | Yan Zheng | Electroluminescent line |
GB2433645A (en) * | 2005-12-13 | 2007-06-27 | Tenso Technologies Ltd | Durable electroluminescent fibre |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5469020A (en) * | 1994-03-14 | 1995-11-21 | Massachusetts Institute Of Technology | Flexible large screen display having multiple light emitting elements sandwiched between crossed electrodes |
US5485355A (en) * | 1992-12-10 | 1996-01-16 | Elam-Electroluminescent Industries Ltd. | Electroluminescent light sources |
-
1995
- 1995-10-26 IL IL11577695A patent/IL115776A0/en unknown
-
1996
- 1996-10-23 AU AU72266/96A patent/AU7226696A/en not_active Abandoned
- 1996-10-23 WO PCT/IL1996/000130 patent/WO1997015939A2/en active Application Filing
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5485355A (en) * | 1992-12-10 | 1996-01-16 | Elam-Electroluminescent Industries Ltd. | Electroluminescent light sources |
US5469020A (en) * | 1994-03-14 | 1995-11-21 | Massachusetts Institute Of Technology | Flexible large screen display having multiple light emitting elements sandwiched between crossed electrodes |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5869930A (en) * | 1996-10-22 | 1999-02-09 | Elam-Electroluminescent Industries Ltd. | Electroluminescent light source with a mixture layer filled with a transparent filler substance |
NL1013742C2 (en) * | 1999-12-03 | 2001-06-06 | Mark Kok | System for generating light by means of electroluminescence. |
WO2001041511A1 (en) * | 1999-12-03 | 2001-06-07 | Mark Kok | System for generating light by means of electroluminescence |
WO2002098177A1 (en) * | 2001-05-31 | 2002-12-05 | Agfa Gevaert N.V. | System for generating light by means of electroluminescence |
DE10232759A1 (en) * | 2002-07-18 | 2004-03-25 | Martin Eickhoff | Novel products - e.g. clothing, fashion accessories, construction site signs - feature enhanced safety and illuminating function and incorporate electroluminescent (EL) cable(s) |
WO2006069517A1 (en) * | 2004-12-29 | 2006-07-06 | Yan Zheng | Electroluminescent line |
GB2433645A (en) * | 2005-12-13 | 2007-06-27 | Tenso Technologies Ltd | Durable electroluminescent fibre |
Also Published As
Publication number | Publication date |
---|---|
WO1997015939A3 (en) | 1997-07-31 |
AU7226696A (en) | 1997-05-15 |
IL115776A0 (en) | 1996-01-19 |
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