Invalidity dossier
US 4729067
Light diffusing device
Current assignee: Mitsubishi Chemical Corp
Added 9/23/2026, 1:30:38 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 — US 4,729,067
Title: Light diffusing device
Patent number: US 4,729,067 (US4729067A)
Inventor: Makoto Ohe
Original assignee: Mitsubishi Rayon Co., Ltd. (recorded assignment dated 1987-11-24)
Current assignee listed: Mitsubishi Chemical Corp. (as listed by the source; not a legal conclusion)
Application number: US06/912,005
Filing/priority date: 1986-09-26
Grant/publication date: 1988-03-01
Legal status shown: Expired – Lifetime (anticipated expiration 2006-09-26)
Purpose
The patent relates to a light diffusing device for evenly illuminating a relatively large area with significantly reduced optical loss. Stated objects are: illuminating a relatively large display surface with uniform brightness; decreasing optical loss; and enabling low-cost, easy production.
Plain-language scope
The device comprises:
(A) a base plate made of (a) a transparent light transmitting layer, (b) a light diffusing layer on the front surface of the transmitting layer, and (c) an intermediate layer between them whose light transmitting and diffusing properties are intermediate between those of the other two layers, the base plate having at least one light incident edge face;
(B) a light reflecting surface layer on the rear surface of the transparent transmitting layer; and
(C) a light diffusing plate arranged on and in the vicinity of the light diffusing layer but not in contact with it.
The background discusses uses such as illumination for advertising displays and rear illumination for liquid crystal displays, and notes problems with matted/roughened-surface diffusing plates (costly, delicate production work). It identifies U.S. Pat. No. 4,059,916 and Japanese Kokai No. 61-55684 as known approaches. Chemical terms appearing in the text include titanium dioxide/titanium oxide, methyl methacrylate, and acrylic resin.
What the excerpt does not establish
The supplied text is explicitly marked as an excerpt with omitted text; it does not provide the full claims, dependent-claim scope, detailed examples, drawings, or the complete description. It does not establish litigation, ownership transfers, validity, enforceability, or the accuracy of the listed assignees or legal status. Prior-art discussion above reflects only the patent's own characterizations.
Generated 10/1/2026, 9:53:05 PM
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Litigation summary
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Proceedings on file (0)
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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.