Invalidity dossier
US 4542449
Lighting panel with opposed 45° corrugations
Current assignee: 3M Co
Added 9/23/2026, 10:12:14 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 — US4542449A
Title: Lighting panel with opposed 45° corrugations
Assignee/Applicant of record (per source): Original assignee Canadian Patents and Development Ltd; current assignee listed as 3M Co (source notes assignee listings may be inaccurate and that no legal analysis was performed).
Key dates (per source): Priority/filing 1983-08-29; publication/grant 1985-09-17; status "Expired – Lifetime." Source states the priority date is an assumption.
Inventor: Lorne A. Whitehead.
Purpose. The patent addresses lighting panels for distributing light from fixtures or luminaires, particularly for diffusing light with a desired directionality—i.e., controlling the angle at which light emerges to reduce direct glare. It notes earlier prismatic panels described in U.S. Pat. No. 2,474,317 (McPhail, 1947) and U.S. Pat. No. 4,064,433 (Korn, 1977).
Plain-language scope. The panel has two transparent dielectric sheets, each with one smooth face and one corrugated face. The corrugation surfaces intersect at 90°, and those surfaces sit at 45° to the smooth face. The first sheet's smooth surface is the light-entry face; its corrugated surface sits adjacent the second sheet's smooth surface; the second sheet's corrugation direction is set at a predetermined angle α to the first sheet's. Light enters the first smooth surface and exits the second corrugated surface. Sheets may be substantially planar; at least one may include light release mechanisms; α may be substantially 90° for maximum directionality, or the sheets may be rotated relative to each other to vary α. The description credits the corrugated sheets with "octature" properties described in U.S. Pat. No. 4,260,220 (Whitehead), incorporated by reference. Figures 3–4 show a U-shaped channel fixing two sheets; FIG. 5 shows a circular panel linked by a rivet/bolt pivot to adjust α. FIG. 2 compares output versus angle for a K-12 prismatic panel (line A) and the invention (line B), with the invention's light concentrated within 30° of normal.
What the excerpt does not establish. The supplied text omits the claims and some description ("[Excerpt only]"), so exact claim scope, dependents, and full limitations are not verifiable here. It gives no litigation, validity, enforceability, or ownership-transfer analysis (transfer entries appear only as source metadata, not legal conclusions).
Source: https://patents.google.com/patent/[US4542449](/patent/US4542449)/en
Generated 10/1/2026, 9:33:42 PM
Cases on file (0)
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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.