Invalidity dossier
US 5961198
Added 9/23/2026, 6:39:05 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US5961198A
Title: Liquid crystal display device and method of manufacturing backlighting light guide panel therefor
Patent number: US5961198A | Application: US08/791,513
Assignee: Original assignee Hitachi, Ltd.; current assignee listed as Panasonic Liquid Crystal Display Co., Ltd.
Key dates: Priority date 1996-02-02; filing date 1997-01-30; publication/grant date 1999-10-05; anticipated expiration 2017-01-30. Legal status listed as "Expired – Lifetime."
Inventors: Yasuo Hira, Hitoshi Taniguchi, Yuji Mori, Yoshie Kodera
Purpose
The patent relates to liquid crystal display devices and methods of manufacturing a backlighting light guide panel for the same. The supplied text notes that backlighting luminance can be increased by raising light-source luminance, but that portable computers, word processors, and similar devices are usually battery- or cell-operated, limiting how much light-source luminance can be increased. The described edge-lighting arrangement addresses uniform backlight luminance.
Plain-language scope (per the excerpt)
In the conventional arrangement of FIG. 3, a lamp such as a cold-cathode or hot-cathode discharge tube serves as a light source (1) placed along one lateral side of a light-transmissive light guide plate/optical waveguide plate (2). A milk-white synthetic-resin diffusing sheet (3) is mounted over the top surface of the light guide plate to uniformize backlight luminance across the display screen. A first prism sheet (4) and second prism sheet (5) are disposed on the diffusing sheet to enhance axial luminance (luminance orthogonal to the display screen) by converging diffused light rays. A light scattering layer (6) is deposited over the rear surface of the light guide plate, opposite the light exit side, to scatter light traveling through the plate toward the diffusing sheet. The light scattering layer is manufactured in a specific structure to further uniformize luminance distribution of exiting light.
Classifications: G02F1/133615 (edge-illuminating devices), G02B6/0036, G02B6/0053, among others.
Source: https://patents.google.com/patent/[US5961198](/patent/US5961198)/en
What the excerpt does not establish: The claims themselves, the specific structure/manufacturing method of the light scattering layer, the detailed description and drawings beyond the FIG. 3 discussion, and the full text of the specification are not included in the excerpt.
Generated 10/1/2026, 9:42:39 PM
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Litigation summary
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PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
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Prior art
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Obviousness
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Extensions
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Derivative works
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