Invalidity dossier
US 6172809
Added 9/23/2026, 2:51:37 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 6,172,809 B1
Title: Surface light source device with polarization function
Patent number: US 6,172,809 B1
Application number: US09/127,822
Inventors: Yasuhiro Koike; Takayuki Arai
Assignee: Enplas Corp (original assignee; current assignee listed as Enplas Corp)
Key dates: Priority date 1994-03-16 (also claims priority from JP07274694A dated 1994-03-16 and JP08371794A dated 1994-03-31); filing date 1998-08-03; granted/publication date 2001-01-09; anticipated expiration 2015-03-13. Legal status: Expired – Lifetime (as listed, and noted as an assumption, not a legal conclusion).
Purpose and plain-language scope: The patent concerns a surface light source device that also performs a polarization function, aimed at applications such as liquid crystal displays (the abstract/description reference liquid crystal substances). It describes a device that produces and outputs light with a controlled polarization state.
According to the supplied text, the device uses a light flux, a "parallelizer," and a polarization function. A key material approach is a light-scattering material comprising a transparent material (matrix) with a modifier and fine particles—including granular material and powdered inorganic compounds such as titanium dioxide (TiO₂), silicon dioxide (SiO₂), and zirconium dioxide (ZrO₂). Polymer materials mentioned include polymethyl methacrylate (PMMA), polycarbonate, polystyrene, and acrylic resin. The text mentions light-scattering by "argon plasma sintering" and references a correlation function. Manufacturing methods noted include mixing, kneading, injection molding, and polymerization.
The excerpt indicates the invention relates to controlling polarization while scattering/diffusing light from a surface light source, though it does not provide full claim language here.
Source: https://patents.google.com/patent/US6172809/en
What the excerpt does not establish: It does not provide the complete claims, specification, or drawings; a full explanation of the parallelizer or polarization mechanism; exact composition ratios or structural configurations; the full abstract; or any findings on validity, enforceability, infringement, or ownership changes. Litigation and prior-art analysis were not researched.
Generated 10/1/2026, 9:51:55 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.