Invalidity dossier
US 5944405
Flat light source using light-diffusing sheet with projections thereon
Current assignee: Dai Nippon Printing Co Ltd
Added 9/23/2026, 9:13:49 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US5944405A
Title: Flat light source using light-diffusing sheet with projections thereon
Patent number: US5944405A
Application number: US08/619,623
Inventor(s): Michiko Takeuchi; Toshikazu Nishio; Taiji Ishii
Assignee: Dai Nippon Printing Co., Ltd. (original and current assignee)
Priority date: 1994-08-12
Filing date: 1995-08-11
Publication/grant date: 1999-08-31
Legal status: Expired – Lifetime (anticipated expiration 2015-08-11)
Source: https://patents.google.com/patent/[US5944405](/patent/US5944405)/en
Purpose / plain-language scope
The patent concerns a flat light source that employs a light-diffusing sheet having projections formed on it. The recurring textual keywords — "light," "heights," "sheet," "light source," and "diffusing sheet" — indicate the disclosure centers on a diffusing sheet whose surface projections of varying heights scatter or distribute light to produce a uniform (flat) illumination output. The abstract and description mention a distribution function, surface roughness, and transparent materials, consistent with engineered surface geometry used to diffuse light evenly. Application contexts referenced in the text include liquid crystals (e.g., backlighting) and general transmission/visualization uses.
Technical signals in the text
- Surface roughness and projection "heights" as the operative diffusion features.
- Distribution functions/measurements used to characterize the projection geometry.
- Materials: transparent materials, plastics/resins (acrylic, methacrylate, polycarbonate, polyester, PET, polystyrene, PMMA), plus particulate/ inorganic additives (silica, TiO₂, calcium carbonate).
- Fabrication mentions: casting, embossing, electroforming, injection molding, sandblasting, plating, deposition, grinding/milling.
- Phrases such as "uniform distribution," "transmittance," and "cumulative effect" reinforce the even-illumination objective.
What this excerpt does not establish
The supplied text is partial: the full claims, abstract prose, detailed description, embodiments, numerical parameters, and drawings are omitted or only keyword-indexed. It does not establish the exact claim scope, specific projection-height ranges or distribution-function formulas, layer stack configuration, measured optical performance, or the cited prior art references. It also does not establish any litigation, ownership transfer beyond the listed assignment, validity, or infringement position — and none of those were researched.
Generated 10/1/2026, 9:40:52 PM
Cases on file (0)
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Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
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
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.