Invalidity dossier
US 6309052
High thermal efficiency ink jet printhead
Current assignee: Hewlett Packard Development Co LP
Added 9/23/2026, 6:15:53 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 6309052 B1
Title: High thermal efficiency ink jet printhead
Patent number: US6309052B1
Application number: US09/385,297
Inventor(s): Rama Prasad; Todd A. Cleland; Robert C Maze; Dale R. Oughton
Original assignee: Hewlett Packard Co
Current assignee (per source): Hewlett Packard Development Co LP
Priority date: 1999-04-30 (claimed from US09/303,250)
Filing date: 1999-08-30
Publication/grant date: 2001-10-30
Legal status: Expired – Lifetime; anticipated expiration 2019-04-30
Purpose and plain-language scope. The patent concerns ink jet printers and, in particular, a low-cost printing system said to include a novel printhead and ink composition providing photographic-quality resolution output. According to the excerpt, ink jet printers print by ejecting small ink drops onto a print medium, positioned by a moving carriage that supports a printhead cartridge containing drop generators. An ink reservoir supplies ink to those generators, which are controlled by a microprocessor or other controller and eject drops at times corresponding to the image pixel pattern. Drops are ejected through a nozzle or orifice by rapidly heating a small volume of ink in a vaporization or firing chamber, typically using an electric heater such as a small thin-film (firing) resistor; passing current through a selected resistor superheats a thin ink layer, causing explosive vaporization and ejection. The excerpt also notes that resolution relates to ink drop size and number, and that increasing dot resolution generally requires greatly decreasing drop size, with an associated disadvantage that is cut off in the excerpt. The classification listing includes bubble jet printhead structures, heating means, resistive element shape, layer structure, segmented heater, and multiple feed channels per ink chamber.
What the excerpt does not establish. The excerpt omits the claims and detailed description (including the stated disadvantage of decreasing drop size, the ink composition, and the specific "high thermal efficiency" structure). It does not establish claim scope, validity, enforceability, litigation, or ownership transfers beyond the recorded assignments shown.
Generated 10/1/2026, 9:42:54 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.