Invalidity dossier
US 5418583
Added 9/23/2026, 6:16:41 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US5418583A
Title: Optical illumination system and projection display apparatus using the same
Patent number: US5418583A
Application number: US08/039,770
Inventor: Yoshihiro Masumoto
Original assignee: Matsushita Electric Industrial Co., Ltd. (current assignee listed as Panasonic Holdings Corp)
Priority date: 1992-03-31
Filing date: 1993-03-30
Publication/grant date: 1995-05-23
Legal status: Expired – Lifetime (anticipated expiration 2013-03-30)
Purpose (from the supplied text): The invention "relates to an optical illumination system to be used mainly to illuminate a light modulator," and also to a projection display apparatus that illuminates a light modulator and projects an enlarged image formed on it onto a screen. An example application is a projection display apparatus using a liquid crystal panel.
Plain-language scope (from the supplied text): The patent addresses nonuniform brightness in lamp-and-concave-mirror illumination (e.g., FIG. 18) and the loss of efficiency when illuminating angle is limited. It describes an optical integrator approach (FIG. 19) in which a first lens array plate and a second lens array plate, each comprising lenses arrayed two-dimensionally, divide a single luminous flux with high brightness nonuniformity into partial luminous fluxes, transmit them, and superimpose them via a third lens to obtain high brightness uniformity. The text notes the conventional system's efficiency depends mainly on optical loss at the second lens array plate, and that the disadvantage is conspicuous with a large radiation source.
Source: https://patents.google.com/patent/[US5418583](/patent/US5418583)/en
What the excerpt does not establish: It is an excerpt only; it does not include the claims, the full description, or the complete list of referenced prior art, so the exact claimed scope and any specific prior-art citations cannot be verified from the supplied text. The excerpt also does not establish litigation outcomes, ownership transfers, or validity. The assignee and legal-status entries are noted as assumptions per the source, not legal conclusions.
Generated 10/1/2026, 9:42:53 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)
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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.