Invalidity dossier
US 6091547
Luminance control film
Current assignee: 3M Innovative Properties Co
Added 9/23/2026, 7:16:35 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 — US6091547A
Title: Luminance control film
Assignee: 3M Innovative Properties Co. (original assignee; a reassignment record dated 2000-01-18 lists assignor Minnesota Mining and Manufacturing Company).
Key dates: Priority date 1994-09-27; filing date 1997-04-30; granted/publication date 2000-07-18; anticipated expiration 2014-09-27. Application number US08/846,955. Legal status listed as "Expired - Lifetime."
Purpose: The patent concerns an optical film for an optical display assembly that controls luminance and viewing angle when combined with a light source. Because a display's light source can represent a substantial fraction of total power draw, reducing power needed for a given luminance extends battery life, which is desirable for battery-powered equipment. The film is a sheet with a linear array of very small prisms — pitch ranging from about one micrometer to approximately thirty micrometers, i.e., roughly two to sixty times the wavelength of light, and large relative to the wavelength. The prisms interact with light from the source to control luminance by diffractive scattering and by "recycling" light (collecting off-axis light and redirecting it on-axis), increasing on-axis luminance at the expense of off-axis luminance and producing a "softer" luminance falloff as the viewer moves off-axis. The disclosed benefits include reduced moiré patterns, since smaller structures raise the spatial frequency of any resultant pattern and diffractive scattering lowers moiré contrast.
Plain-language scope: A single sheet may be placed over a light source; alternatively, two sheets can be stacked with prism axes "crossed" to form a luminance control film assembly. Figures illustrate the film and assembly, display assemblies incorporating them, and luminance-versus-viewing-angle, horizontal-versus-vertical scan, and gain-versus-pitch/apex-angle data.
What the excerpt does not establish: It does not provide the full claims, the complete written description, examples, or numerical claim limitations; the source text is explicitly marked as excerpted, with text omitted after FIG. 8's description. It also does not establish validity, enforceability, or the accuracy of the legal status/assignment listings (Google states these are assumptions, not legal conclusions).
Source: https://patents.google.com/patent/[US6091547](/patent/US6091547)/en
Generated 10/1/2026, 9:42:12 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
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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.