Invalidity dossier
US 5671994
Flat and transparent front-lighting system using microprisms
Current assignee: CLIO TECHNOLOGIES Inc
Added 9/23/2026, 2:41:33 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 5,671,994 A
Title: Flat and transparent front-lighting system using microprisms
Patent number: US 5,671,994 A
Application number: US 08/255,378
Inventors: Ping-Kaung Tai; Han Zou
Original assignee: Clio Tech Inc (current assignee listed as CLIO TECHNOLOGIES Inc / Clio Tech Inc)
Priority/filing date: 1994-06-08
Publication (grant) date: 1997-09-30
Legal status (as listed): Expired – Lifetime; anticipated expiration 2014-09-30
Purpose: Per the supplied excerpt, the invention "relates generally to lighting systems and particularly to an efficient, flat and transparent front-lighting system suitable for a wide range of applications such as illuminating automobile meters, road signs, reflective displays, shopping windows, high lighting pictures, jewelry, and art work." The excerpt also states it "functions as a se…" (sentence truncated in the supplied text).
Plain-language scope: The title and prior-art keywords ("light," "light pipe," "pipe assembly," "microprisms," "assembly") indicate a lighting system in which light is guided through a flat, transparent light pipe and directed by microprisms. The classification entries confirm subject matter directed to planar/plate-like light guides, coupling light in and out, prismatic refractors, front illuminating devices, and their use with liquid crystal displays.
Family/related filings noted: PCT/US1995/007293 (WO1995034009A1); US 08/824,002 (US5860722A); US 08/899,986 (US6092904A).
Source: https://patents.google.com/patent/US5671994/en
What the excerpt does not establish:
- The full text of the specification, drawings, or claims (the excerpt is truncated and contains no claim language or detailed description). Therefore the precise claimed scope cannot be stated.
- The complete sentence beginning "It also functions as a se…" is cut off.
- No information is provided on examination, cited prior art, litigation, or ownership transfers; consistent with the instructions, none is asserted here.
- The assignee listing is expressly noted in the source as possibly inaccurate and not legally analyzed.
Generated 10/1/2026, 9:52:03 PM
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Litigation summary
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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.