Invalidity dossier
US 6120280
Added 9/23/2026, 10:24:07 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 6,120,280 A
Title: Microprism master mold
Assignee: Nippon Carbide Industries Co., Inc. (original assignee: Nippon Carbide Kogyo Kabushiki Kaisha)
Inventors: Ikuo Mimura; Keiji Adachi
Priority date: 1995-07-28
Filing date: 1996-07-26
Grant/publication date: 2000-09-19
Application number: US09/000,454
Legal status (as listed): Expired – Lifetime (anticipated expiration 2016-07-26)
Purpose. The patent concerns microprism master molds for producing cube-corner type retroreflectors—articles that reflect most incident light back toward the light source. The disclosed molds are intended for making retroreflective elements and sheeting used in road and construction signs, license plates, safety clothing and life-saving devices, markings and signboards, and reflectors for visible-light or laser reflection sensors. The stated aim is retroreflective sheeting with excellent wide-angle properties.
Plain-language scope. The background explains that cube-corner prism sheeting has higher retroreflection efficiency than micro glass bead sheeting but suffers reduced efficiency as the angle of incidence grows, and its brightness varies with the direction of incident light (rotation angle characteristics). Wide-angle properties are framed around three considerations: observation angle, incident angle, and rotation angle characteristics. A known approach divides the prism array surface into zones whose prisms have changed angular orientation. The excerpt also reviews formation methods—bundled metallic pins (impractical above about 2,000 microprisms per square centimeter), flat-sheet V-groove cutting (limited to triangular prisms), and pin-bundling versus sheet methods—and notes that observation angle is usually at most about 3°.
Not established by this excerpt. The excerpt is a background/definitions portion only; it does not supply the actual claims, the specific mold structure or geometry recited, embodiments, drawings, or the precise inventive scope. No litigation, ownership-transfer, validity, or prior-art conclusions are drawn here. Classifications listed include B29D11/00625 (moulds for reflex reflectors) and G02B5/124.
Generated 10/1/2026, 9:33:26 PM
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Litigation summary
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Proceedings on file (0)
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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
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.