Invalidity dossier
US 6027221
Surface light source device of side light type and mold for light guide plate employed in the device
Current assignee: Enplas Corp
Added 9/23/2026, 7:52:06 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 6,027,221 A
Title: Surface light source device of side light type and mold for light guide plate employed in the device
Assignee/Inventor data (as listed in the source): Original assignee Enplas Corp; Yasuhiro Koike also listed. Inventors: Tsuyoshi Ishikawa and Hiroshi Yamazaki. Assignment to Enplas Corporation and Koike, Yasuhiro recorded 1997-12-31.
Key dates: Priority date 1996-08-05; filing date 1997-07-31 (application US08/904,348); publication/grant 2000-02-22; anticipated expiration 2017-07-31; status Expired – Lifetime. Source notes litigation-family markers, but this overview does not examine them.
Purpose (per the text): The invention "relates to a surface light source device of side light type applied to a liquid crystal display or the like, and a mold for a light guide plate employed in the device, and more particularly, to a surface light source device of side light type employing a light guide plate with emitting directivity and a mold for forming the light guide plate." Such devices illuminate a liquid crystal panel from behind and suit thin overall construction.
Plain-language scope (from the excerpt): A rod-shaped primary light source (e.g., a cold cathode tube) sits beside a plate-shaped light guide; its light enters through a side end surface and exits a major surface. The described embodiment uses a wedge-section light-scattering guide plate of PMMA matrix with light-transmitting fine particles of differing refractive index, arranged with a reflection sheet and a prism sheet (prism surface facing the guide plate) whose triangular projections run substantially parallel to the incidence surface, redirecting emitted light frontally. Emitted light is described as scattered and tilted away from the light source, i.e., having directivity. The text also mentions light guide plates having a scattering film or roughened surface, a prism sheet with prism surfaces on both sides, and classification under G02B6/00 groups including prismatic/brightness-enhancement sheets.
What the excerpt does not establish: It does not provide the full claims (31 claims are noted only in a count), full description, drawings, detailed mold structure, examples, or figures. It supplies no evidence on validity, infringement, prior art, ownership changes, or litigation outcomes.
Generated 10/1/2026, 9:41:45 PM
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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.