Patent US1861508A successfully refreshed from Google Patents.
Patent EP0271956A2 successfully refreshed from Google Patents.
EP0271956A2
Expired / Lapsed
EP
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A liquid crystal display illumination system
Assignee: Koninklijke Philips NV
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Filing: 1987-12-10
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Granted: —
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Expires: 2007-12-10
Abstract
Abstract An illumination system is provided for a liquid crystal display panel. The panel 1 is placed to transmit light 2 from a light source 3 to a viewing location, the light source being an extended area source of omnidirectional light of high efficiency, such as a fluorescent tube. A light guide 6 is placed between the source and the panel, the light guide comprising a transparent input face 7 adjacent the source, a transparent output face 10 adjacent the panel, and reflective side walls 11 transverse to the input and output faces. The light guide is tapered, the input face being smaller in area than the output face. The divergence of light from the source is thereby reduced as it passes through the panel. The LCD panel then functions with an improved contrast range.
Inventors
- 👤 John Alfred Clarke
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 21:54
CPC Classifications
G; G09; G09F; G09F13/00; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/133524
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
100 words
An illumination system for a liquid crystal display panel wherein the panel is placed to transmit light from a light source to a viewing location, characterised in that the light source is an extended area source of omnidirectional light, in that a light guide is placed between the source and the panel, the light guide comprising a transparent input face adjacent the source, a transparent output face adjacent the panel, and reflective side walls transverse to the input and output faces, and in that the light guide is tapered, the input face being smaller in area than the output face.
Claim 2
Dependent Claim
100 words
An illumination system for a liquid crystal display panel wherein the panel is placed to transmit light from a light source to a viewing location, characterised in that the light source is an extended area source of omnidirectional light, in that a light guide is placed between the source and the panel, the light guide comprising a transparent input face adjacent the source, a transparent output face adjacent the panel, and reflective side walls transverse to the input and output faces, and in that the light guide is tapered, the input face being smaller in area than the output face.
Claim 3
Dependent Claim
18 words
An illumination system as claimed in Claim 1, characterised in that the output face comprises a positive lens.
Claim 4
Dependent Claim
41 words
An illumination system as claimed in Claim 1 or Claim 2, characterised in that the guide comprises a transparent material of a refractive index higher than that of the surrounding space whereby the side walls are reflective by total internal reflection.
Claim 5
Dependent Claim
24 words
An illumination system as claimed in Claim 3, characterised in that the output face is convex toward the panel thereby forming a positive lens.
Claim 6
Dependent Claim
29 words
An illumination system as claimed in any one of the preceding claims, characterised in that the side walls are curved in planes transverse to the input and output faces.
Claim 7
Dependent Claim
54 words
An illumination system for a liquid crystal display panel, characterised in that a plurality of illumination systems as claimed in any one of the preceding claims are assembled so that the output faces of the light guides are adjacent to one another to cover the whole area of an extended liquid crystal display panel.
Claim 8
Dependent Claim
33 words
An illumination system as claimed in Claim 6, characterised in that the output faces are identical to one another and are arranged in regular rows and columns to cover the extended display panel.
Claim 9
Dependent Claim
19 words
An illumination system as claimed in Claim 7, characterised in that the output faces and input faces are rectangular.
Claim 10
Dependent Claim
47 words
An illumination system as claimed in any one of Claims 6, 7 or 8, characterised in that feeder light guides are provided one each for the tapered light guides, each feeder guide coupling an area of the source to the input face of the associated tapered guide.
Claim 11
Dependent Claim
25 words
An illumination system as claimed in any one of the preceding claims, characterised in that the source comprises a phosphor layer energised to produce light.
Claim 12
Dependent Claim
27 words
An illumination system as claimed in Claim 10, characterised in that the phosphor layer is energised by ultra-violet radiation from a gas discharge in a fluroescent tube.
Claim 13
Dependent Claim
46 words
An illumination system as claimed in Claim 11, characterised in that a part of the phosphor layer not coupled to a feeder guide is reflective to direct light back into the fluorescent tube and onto a part of the phosphor layer coupled to a feeder guide.
Claim 14
Dependent Claim
69 words
An illuminating system as claimed in Claim 11, characterised in that an envelope of the fluorescent tube is transparent to ultra-violet radiation, in that the phosphor layer is confined to the area of the tube envelope facing a feeder guide, and in that a part of the tube envelope not facing a feeder guide is reflective, to direct ultra-violet radiation back into the tube and onto the phosphor layer.
Claim 15
Dependent Claim
35 words
An illumination system as claimed in any one of the preceding claims, characterised in that a light-diffusing screen is placed adjacent to the liquid crystal display panel on the side remote from the light guide.
Claim 16
Dependent Claim
20 words
An illumination system as claimed in Claim 14, characterised in that the light diffusing screen comprises a cylindrical lens array.
References Cited (Backward Citations)
No citation records indexed.
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