Backlighting device

Assignee: Tosoh Corp

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Filing: 1992-03-20

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Granted: —

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Expires: 2012-03-20

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Abstract

Abstract A backlighting device for display panels operating on the edge lighting method that comprises a light conducting plate made of a light-transmissive material, a layer of light-diffusing material that partly covers one major surface of said light conducting plate, and a light diffusing/reflecting plate that covers the thus covered area of the light conducting plate, which device is characterized in that the light conducting plate is provided on its exit face with a film that is coarser grained on the exit face than on the entrance face (the side closer to the light conducting plate) and which, when provided on the exit face of the light conducting plate, will increase the luminance of light issuing from the exit face of that light conducting plate. This backlighting device produces satisfactory luminance and can be used as a high-performance model that achieves a high efficiency of power to luminance conversion at least in the direction of the line normal to the exit face. <IMAGE>

Inventors

👤 Keiji Kashima
👤 Osamu Shoji
👤 Naoki Yoshida

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-11-01 22:01

CPC Classifications

G; G02; G02B; G02B6/00; G02B6/0001; G02B6/0011; G02B6/0033; G02B6/005; G02B6/0051; F; F21; F21V; F21V7/00; G02B6/0035; G02B6/0036; G02B6/0055

Claims Analysis

Total Claims: 7

Claim 1

Independent Claim 109 words

In a backlighting device for display panels that comprises: a light conducting plate made of a light-transmissive material, said light conducting plate having a light-diffusing element; a specular reflecting or light diffusing/reflecting plate that covers the thus covered area of the light conducting plate; and a linear light source provided in proximity to the end portion of at least one side of said light conducting plate; the improvement wherein said light conducting plate is provided on its exit face with at least one film of a light-transmissive material that is coarser grained on the exit face than on the entrance face (the side closer to said light conducting plate).

Claim 2

Dependent Claim 82 words

A backlighting device according to claim 1 wherein said film of a light-transmissive material has a coarser grained surface on the exit side than on the entrance side (which is the closer to the light conducting plate) and, when provided on the exit face of the light conducting plate, will increase the luminance of light issuing from the exit face of said light conducting plate as measured in the direction of a line substantially normal to the exit face of said film.

Claim 3

Dependent Claim 89 words

A backlighting device according to claim 1 wherein the grained exit face of the film of a light-transmissive material has surface asperities and, when examined under a microscope at a magnification of 100, said face is such that the difference in height between a concave and an adjacent convex as taken in the direction of the line normal to the exit face or the distance between adjacent concaves or convexes as taken in the direction parallel to the exit face is in the range of 10 to 1,000 µm.

Claim 4

Dependent Claim 89 words

A backlighting device according to claim 2 wherein the grained exit face of the film of a light-transmissive material has surface asperities and, when examined under a microscope at a magnification of 100, said face is such that the difference in height between a concave and an adjacent convex as taken in the direction of the line normal to the exit face or the distance between adjacent concaves or convexes as taken in the direction parallel to the exit face is in the range of 10 to 1,000 µm.

Claim 5

Dependent Claim 50 words

A backlighting device according to claim 1 wherein said light-diffusing element is formed in such a manner that a light-diffusing material partly covers one major surface of said light conducting plate, said light-diffusing material having a higher reflective index than the material of which said light conducting plate is made.

Claim 6

Dependent Claim 45 words

A backlighting device according to claim 1 wherein the coarser grained exit face of said film is a surface the vertical angle of which is in the range of 80 to 150 degree when said film is cut so as obtain a minimum vertical angle.

Claim 7

Dependent Claim 46 words

A backlighting device according to claim 2 wherein the coarser grained exit face of said film is a surface the vertical angle of which is in the range of 80 to 150 degree when said film is cut so as to obtain a minimum vertical angle.

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