Invalidity dossier
US 4729185
Display panel illumination device
Current assignee: Toshiba Corp
Added 9/23/2026, 3:11:02 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: US4729185A — "Display Panel Illumination Device"
Bibliographic data (from source):
- Patent number: US4729185A
- Application number: US06/823,391
- Inventor: Masaharu Baba
- Original assignee: Toshiba Corp (assignment recorded as KABUSHIKI KAISHA TOSHIBA, A CORP. OF JAPAN; assignor: Baba, Masaharu)
- Priority date: 1985-01-30
- Filing date: 1986-01-28
- Publication/grant date: 1988-03-08
- Legal status listed: Expired - Fee Related; anticipated expiration 2006-01-28
- Source URL: https://patents.google.com/patent/[US4729185](/patent/US4729185)/en
Purpose: The invention relates to a surface illumination device for a display panel, suitable for rear surface illumination such as a liquid crystal display panel. Such devices are described as installed in motor vehicles and airplanes to illuminate characters and figures on display panels from the rear, and must satisfactorily illuminate an area corresponding to the total area of the display panel.
Plain-language scope: The described device has three elements: a display member for transmitting predetermined information; a light source for illuminating the display member; and a light guiding member for guiding light from the light source to the display member — the light guiding member being made of a flexible transparent or translucent material.
The excerpt contrasts this with a conventional arrangement: a rigid acrylic light guiding member with a baseless incandescent lamp inserted into a lamp insertion hole, a curved rear surface, and a reflecting or satin-finish (sandblasted) surface. The excerpt states drawbacks of the rigid member — susceptibility to heat deformation, lack of flexibility/elasticity causing reduced illuminance at the panel, need for a sufficiently large lamp hole and cooling space, and the need for separate molding for differently curved panels (e.g., arcuated panel 16a vs. panel 16b). Because the flexible light guiding member can be bent, the excerpt states it offers advantages over the conventional member.
What the excerpt does not establish: The supplied text is explicitly marked as an excerpt with omitted material. It does not include the full claims, the complete description, any drawing reference numerals beyond those mentioned (10, 12, 14, 16, 16a, 16b, 18), or the specific test data behind the stated advantages. No independent claims are quoted, so the exact metes and bounds of the claimed invention are not established here. Nothing about litigation, ownership transfers, validity, or prior art is addressed. The classifications and keyword listings in the source are machine-generated metadata, not legal conclusions.
Generated 10/1/2026, 9:51:45 PM
Cases on file (0)
Specific litigation cases in our database that name US patent 4729185. 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.