US5955837A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electroluminescent illumination system with an active layer of a medium having light-scattering properties for flat-panel display devices
Assignee: US Philips Corp
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Filing: 1997-10-10
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Granted: 1999-09-21
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Expires: 2017-10-10
Abstract
Abstract The illumination system (1) has a substrate (2) and an active layer (3) comprising an electroluminescent material, in which the active layer (3) is present between a first, optically transparent electrode layer (5) and a second electrode layer (7). The illumination system (1) is characterized in that a light-scattering layer (28) comprising a medium having light-scattering properties is present in a forward direction (29) with respect to the active layer (3), in which the non-scattered fraction of a (collimated) light beam, when passed through the light-scattering layer (8) in the forward direction (29), is in the range between 0.05 and 0.8, preferably in the range between 0.1 and 0.5. The light-scattering properties of the medium are preferably stronger as the light is more obliquely incident, as is achieved by using birefringent particles and/or media. A very suitable light-scattering layer (28) is a (half) monolayer of TiO 2 particles provided on the substrate (2), with an average size of the (spherical) particles of 0.1-1 μm. The light output of the illumination system (1) is further improved by providing the edges of the substrate (2) with a reflective coating (26).
Inventors
- 👤 Jeroen J. L. Horikx
- 👤 Coen T. H. F. Liedenbaum
- 👤 Martinus B. Van Der Mark
- 👤 Adrianus J. M. Berntsen
- 👤 Jeroen J. M. Vleggaar
- 👤 Henri M. J. Boots
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 23:23
CPC Classifications
H; H05; H05B; H05B33/00; H05B33/12; H05B33/22; H10; H10K; H10K50/00; H10K50/80; H10K50/85; H10K50/854; H10K59/00; H10K59/80; H10K59/875; H10K59/877
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
113 words
An illumination system (1) comprising a substrate (2) and an active layer (3) comprising an electroluminescent material, said active layer (3) being provided between a first major surface of a first, optically transparent electrode layer (5) and a second electrode layer (7), wherein a light-scattering layer (2', 8, 8', 28, 28') comprising a medium having light-scattering properties is present adjacent a second, opposite major surface of the transparent electrode layer (5), in which a non-scattered fraction of a light beam, when passed through the light-scattering layer (2', 8, 8', 28, 28') at an angle transverse to said layer (2', 8, 8', 28, 28'), is in the range of between about 0.05 and 0.8.
Claim 2
Dependent Claim
113 words
An illumination system (1) comprising a substrate (2) and an active layer (3) comprising an electroluminescent material, said active layer (3) being provided between a first major surface of a first, optically transparent electrode layer (5) and a second electrode layer (7), wherein a light-scattering layer (2', 8, 8', 28, 28') comprising a medium having light-scattering properties is present adjacent a second, opposite major surface of the transparent electrode layer (5), in which a non-scattered fraction of a light beam, when passed through the light-scattering layer (2', 8, 8', 28, 28') at an angle transverse to said layer (2', 8, 8', 28, 28'), is in the range of between about 0.05 and 0.8.
Claim 3
Dependent Claim
20 words
An illumination system as claimed in claim 1, wherein the non-scattered fraction is in the range between 0.1 and 0.5.
Claim 4
Dependent Claim
16 words
An illumination system as claimed in claim 1, wherein the substrate (2') comprises the light-scattering medium.
Claim 5
Dependent Claim
29 words
An illumination system as claimed in claim 1, wherein the light-scattering layer (8) is present at a side of the substrate (2) facing away from the active layer (3).
Claim 6
Dependent Claim
54 words
An illumination system as claimed in claim 1, wherein the light-scattering medium has anisotropic light-scattering properties, with light emitted by the active layer (3) and propagating in the light-scattering medium in a direction transverse to the active layer (3) being scattered to a smaller extent than light propagating in the medium in other directions.
Claim 7
Dependent Claim
31 words
An illumination system as claimed in claim 5, wherein the light-scattering medium (18') comprises aspherical particles (21), whose longitudinal axis is directed in a direction transverse to the active layer (3).
Claim 8
Dependent Claim
62 words
An illumination system as claimed in claim 5, wherein the light-scattering medium (18") comprises particles (22) which scatter light, in which a component (n z ) of the refractive index of the particles (22) in the direction transverse to the active layer (3) differs from the other components (n x , n y ) of the refractive index of the particles (22).
Claim 9
Dependent Claim
63 words
An illumination system as claimed in claim 5, wherein the light-scattering medium (18"') comprises particles (23) which scatter light, in which a component (n z ) of the refractive index of the light-scattering medium (18"') in the direction transverse to the active layer differs from the other components (n x , n y ) of the refractive index of the light-scattering medium (18"').
Claim 10
Dependent Claim
31 words
An illumination system as claimed in claim 1, wherein the light-scattering layer comprises two components having different refractive indices, the refractive index difference between the two components being larger than 0.05.
Claim 11
Dependent Claim
21 words
An illumination system as claimed in claim 1, wherein edges of the substrate (2) are provided with a reflective coating (26).
Claim 12
Dependent Claim
28 words
An illumination system as claimed in claim 1, wherein the light-scattering medium comprises a compound from the group of silicon nitride, tantalum oxide, niobium oxide and titanium oxide.
Claim 13
Dependent Claim
15 words
An illumination system as claimed in claim 11, wherein the material comprises TiO 2 .
Claim 14
Dependent Claim
15 words
An illumination system as claimed in claim 11, wherein the material comprises substantially spherical particles.
Claim 15
Dependent Claim
22 words
An illumination system as claimed in claim 13, wherein the particles have an average diameter of between 0.1 μm and 1 μm.
Claim 16
Dependent Claim
20 words
An illumination system as claimed in claim 11, wherein the layer comprises a part of a monolayer of the material.
Claim 17
Dependent Claim
83 words
An illumination system (1) comprising a substrate (2) and an active layer (3) comprising an electroluminescent material, said active layer (3) being provided between a first major surface of a first, optically transparent electrode layer (5) and a second electrode layer (7), wherein a light-scattering layer (28) comprising a medium having light-scattering properties is present adjacent a second, opposite major surface of the transparent electrode layer (5), and in that minor surfaces of the substrate (2) are provided with a reflective coating (26).
Claim 18
Dependent Claim
83 words
An illumination system (1) comprising a substrate (2) and an active layer (3) comprising an electroluminescent material, said active layer (3) being provided between a first major surface of a first, optically transparent electrode layer (5) and a second electrode layer (7), wherein a light-scattering layer (28) comprising a medium having light-scattering properties is present adjacent a second, opposite major surface of the transparent electrode layer (5), and in that minor surfaces of the substrate (2) are provided with a reflective coating (26).
Claim 19
Dependent Claim
109 words
A display device of the flat-panel type, comprising an illumination system (1) comprising a substrate (2) and an active layer (3) comprising an electroluminescent material, said active layer (3) being provided between a first major surface of a first, optically transparent electrode layer (5) and a second electrode layer (7), wherein a light-scattering layer (2',8,8',28,28') comprising a medium having light-scattering properties is present adjacent a second, opposite major surface of the transparent electrode layer (5), in which a non-scattered fraction of a light beam, when passed through the light-scattering layer (2',8,8',28,28') at an angle transverse to said layer (2',8,8',28,28'), is in the range of between about 0.05 and 0.8.
Claim 20
Dependent Claim
109 words
A display device of the flat-panel type, comprising an illumination system (1) comprising a substrate (2) and an active layer (3) comprising an electroluminescent material, said active layer (3) being provided between a first major surface of a first, optically transparent electrode layer (5) and a second electrode layer (7), wherein a light-scattering layer (2',8,8',28,28') comprising a medium having light-scattering properties is present adjacent a second, opposite major surface of the transparent electrode layer (5), in which a non-scattered fraction of a light beam, when passed through the light-scattering layer (2',8,8',28,28') at an angle transverse to said layer (2',8,8',28,28'), is in the range of between about 0.05 and 0.8.
References Cited (Backward Citations)
US3178580A
Cited
US3200279A
Cited
US3074816A
Cited
US4099091A
Cited
US4734618A
Cited
US5700591A
Cited
US5504389A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2002-09-20 | 2003-03-22 | 2003-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-09-20 | 2007-03-22 | 2007-09-21 | $3760.00 | Window Closed / Lapsed |
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