Invalidity dossier
US 5737501
Printer control unit and method
Current assignee: Canon Inc
Added 9/24/2026, 12:27:37 AM
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 5,737,501 A — "Printer Control Unit and Method"
Bibliographic data (from supplied text): Inventor Kiyohiro Tsunekawa; original assignee Canon Inc. (Canon Kabushiki Kaisha); application US 08/677,108; filed 1996-07-09; priority date 1995-07-14; granted/publication date 1998-04-07; status listed as "Expired - Lifetime," with anticipated expiration 2016-07-09. Classification: G06K 15/02 and related G06K 2215 subclasses.
Purpose: The patent addresses printer control for drawing images from drawing objects described in an intermediate data format generated from external print data. The background describes the "banding method" — rasterizing one band while sending another at fixed speed to the printer engine — and the "full-paint method" using a one-page raster memory. Banding saves memory and can speed processing, but when resources are insufficient the system may "degrade," lowering processing resolution by thinning a 600 dpi object down to 300 dpi, which loses or distorts data. Font data may also be deleted or replaced mid-printing, so thinning is applied uniformly to avoid rewriting pattern contents, further degrading output quality.
Plain-language scope: The disclosure concerns a printer control unit and method with (1) drawing object forming means to make intermediate-format drawing objects from input print data, and selection means to choose font object forming means according to the font type of a reference drawing object when an image must be formed at a resolution differing from the reference object's resolution; (2) forming means that reuses a shared, undeleted font object when the same character type and code are requested again, plus reforming means to create a second font object at a different resolution when needed; and (3) corresponding method steps. The excerpt also describes preparing a low-resolution raster memory from band-raster memory and free space recovered by thinning a drawing object. Twelve figures cover an LBP construction, block diagrams, flowcharts, and font cache structures across four embodiments.
Not established by the excerpt: Full claims, the complete specification and omitted text, exact claim language or breadth, examination history, and the accuracy of the listed legal status, assignee, or priority date (Google states these are assumptions). No litigation, ownership-transfer, validity, or prior-art conclusions are drawn, per instruction.
Generated 10/1/2026, 9:31:57 PM
Cases on file (0)
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Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
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.