Invalidity dossier
US 5851062
Added 9/23/2026, 3:57:15 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US5851062A
Title: Prism sheet for surface light source
Patent number: US5851062A
Application number: US08/694,695
Inventors: Masayuki Shinohara, Yutato Okuno, Shigeru Aoyama
Assignee: Omron Corporation (original and current assignee listed)
Priority date: 1995-08-11
Filing date: 1996-08-09
Publication/grant date: 1998-12-22
Legal status: Expired – Lifetime (anticipated expiration 2016-08-09)
Purpose: The invention addresses prism sheets used in surface light sources (e.g., backlights for LCDs). In conventional prism sheets, some light exits in a "side mode" at large angles outside the desired viewing range, reducing frontal luminance. The stated objective is to reduce side-mode light and thereby increase frontal luminance.
Plain-language scope: The patent describes a prism sheet with a periodic pattern of regularly repeated angled edges, described as an M-shaped pattern. A cross section of one minimal unit of the periodic pattern has at least four surface slopes, each slope facing opposite the next — that is, positive and negative slopes alternate relative to the sheet's surface direction. Among the four slopes, the central two are shorter than the other two, and these shorter slopes form a shallow groove in each periodic pattern. The specification characterizes light behavior in three modes — front, recurrent, and side — and identifies side mode as the most significant for improving prism sheet function.
Source: https://patents.google.com/patent/[US5851062](/patent/US5851062)/en
What the excerpt does not establish: The excerpt is partial; figures 4 onward, full claim language, dependent claims, and detailed embodiments are omitted, so the precise claimed scope cannot be verified from this text. It also does not establish examination history, any prior-art references, validity, enforceability, litigation, or ownership changes beyond the recorded assignment and current-assignee listing. Classifications shown (G02B6/0053, F21V5/02) are as listed in the source.
Generated 10/1/2026, 9:51:14 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.