Invalidity dossier
US 4985710
Buttable subunits for pagewidth "Roofshooter" printheads
Current assignee: Xerox Corp
Added 9/23/2026, 10:04:12 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 — US 4985710 A
Title: "Buttable subunits for pagewidth 'Roofshooter' printheads"
Patent number / application: US 4985710 A; Application US07/442,641
Assignee: Xerox Corp (original assignee); inventors Donald J. Drake and William G. Hawkins
Key dates: Priority/filing date 1989-11-29; publication (grant) date 1991-01-15; anticipated expiration 2009-11-29. Status listed as "Expired – Lifetime." (Legal status is stated in the source as an assumption, not a legal conclusion.)
Purpose (from the excerpt): The invention "relates to methods of fabricating thermal ink jet printheads, and particularly to methods of fabricating pagewidth 'roofshooter' printheads from an array of silicon wafer subunits (or chips)." A pagewidth printer has a stationary printhead whose length equals or exceeds the paper width, with paper moved continuously past it. "Roofshooter" printheads are described (per U.S. Pat. No. 4,789,425 to Drake et al.) as those expelling droplets from nozzles in the printhead roof along trajectories perpendicular to the heating element surfaces, such as nozzles 12, channelled recess 18, heating element 34, and feed slot 20 shown in FIGS. 1–2.
Plain-language scope (based only on the title and the stated purpose): The patent concerns making full-page-width thermal ink jet printheads by combining multiple silicon wafer subunits or chips ("buttable subunits"), and methods of fabricating them. The excerpt describes background thermal ink jet systems, carriage-type versus pagewidth printers, and roofshooter structure and ink flow, but does not reproduce the claims.
Source: https://patents.google.com/patent/US4985710/en
What the excerpt does not establish: It does not reproduce the claims, dependent claims, detailed description, or drawing text, so the precise claimed scope cannot be stated. It does not establish the full technical content, embodiments, or any limitations beyond background discussion. It does not establish validity, enforceability, litigation, or ownership beyond the listed assignments, and no such matters are addressed here. The patent number and identifiers are treated literally as supplied.
Generated 10/1/2026, 9:33:48 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
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.