Invalidity dossier
US 5711589
Plane light source unit
Current assignee: Mitsubishi Chemical Corp
Added 9/23/2026, 1:28:10 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 5,711,589 A
Title: Plane light source unit
Source: https://patents.google.com/patent/US5711589/en
Bibliographic data (as listed): Inventors Makoto Oe and Issei Chiba; original assignee Mitsubishi Rayon Co. Ltd.; current assignee listed as Mitsubishi Chemical Corp. Application no. US08/630,467, filed 1996-04-10; publication date 1998-01-27. Priority date listed as 1993-06-22; the record also shows priority filings to CA2099067 (1993-06-23) and EP93305025 (1993-06-28). Legal status listed as "Expired – Lifetime," with anticipated expiration 2013-06-22. Related application US08/941,041 published as US5863113A.
Purpose: The patent relates to a plane light source unit, particularly for backlighting a liquid crystal display device. The record describes conventional backlighting assemblies—a linear lamp at the focus of a parabolic reflector with a milk-white diffusing plate above it—and notes drawbacks: attaining high-quality display requires a thick unit (a 10–12 inch display requiring 20–30 mm thickness), so thin units are difficult; luminance decreases with distance from the light source, producing uneven luminance; and shaped members intended to alter light paths require precise, costly working and utilize only a small portion of incident light. Cited background includes Japanese Laid-open (Tokukai-Hei) 1-245220 and 1-107406, which use light-diffusing-material layers or fine dot patterns whose density increases with distance from the light-incidence portion.
Plain-language scope: The unit uses a transparent, plate-shaped light guide (e.g., acrylic resin) into which light enters at one end surface and is emitted from the upper or lower surface. The classifications emphasize coupling-out features that vary in density, size, shape or depth along the guide to give homogeneous output, and separate entries cover prismatic/brightness-enhancement sheets, linear grooves, and scattering dots.
What the excerpt does not establish: It contains no claims, so claim scope cannot be stated. The definitions excerpt ends mid-sentence ("a lo…"), and the omitted text presumably contains the detailed description, claims, and any drawing descriptions. The excerpt establishes nothing about litigation, ownership transfers (beyond the listed assignees), validity, or prior-art analysis, and it does not confirm that the listed legal status or assignee data was verified.
Generated 10/1/2026, 9:53:07 PM
Cases on file (0)
Specific litigation cases in our database that name US patent 5711589. The free-form analysis below may also discuss cases beyond this list.
No cases on file mention this patent. Upload a CSV or add a case manually in Admin → Manage litigation cases.
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.