Invalidity dossier
US 6139131
High drop generator density printhead
Current assignee: Hewlett Packard Development Co LP
Added 9/23/2026, 10:24:27 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: US6139131A — "High drop generator density printhead"
Bibliographic data (from supplied text). Patent number US6139131A; application US09/386,028; filing date 1999-08-30; priority date 1999-08-30; publication/grant date 2000-10-31. Inventors: Rama Prasad, Todd A. Cleland, Robert C. Maze, Dale R. Oughton. Original assignee: Hewlett Packard Co; current assignee listed as Hewlett Packard Development Co LP (the source notes listed assignees may be inaccurate). Legal status: expired — lifetime; anticipated expiration 2019-08-30. Classifications include B41J2/14 (nozzle/on-demand inkjet head structure), B41J2/14112 (resistive element), B41J2/14129 (layer structure), B41J2002/14177 (segmented heater), and B41J2/045-related driving/control subclasses. Related filings noted: EP1080904B1, EP1563999B1, JP3526822B2, JP3588459B2, DE60018862T2, DE60040493D1.
Purpose. The invention "relates generally to inkjet printing devices, and more particularly to an inkjet printhead for thermal inkjet printing devices that provides a high density of ink drop generators for ejecting ink from the printhead."
Plain-language scope. The supplied text explains the operating context rather than the claims: a thermal inkjet printer uses translationally reciprocating print cartridges; the printhead's orifice plate has small nozzles; beneath each nozzle is an ink firing chamber holding ink before ejection; ink reaches the chambers via channels in fluid communication with an ink reservoir (in the cartridge or a separate container). Ejection occurs by quickly heating ink in the firing chamber with a selectively energized electrical pulse to a heater resistor ejector; an ink vapor bubble nucleates at the resistor surface or its protective layers, and its rapid expansion forces liquid ink through the nozzle. The excerpt mentions "the minimum electrical energy required to eject an ink" but the sentence is truncated.
Not established by the excerpt. The full claims are absent, so the metes and bounds of the claimed invention — particularly the structural or electrical means by which "high drop generator density" is achieved — are not shown here. The excerpt also does not establish specific numerical densities, resistor geometries, prior-art references, or the omitted portion of the energy discussion.
Source: https://patents.google.com/patent/[US6139131](/patent/US6139131)/en
Generated 10/1/2026, 9:33:25 PM
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Litigation summary
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PTAB challenges
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Assignment history
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Prior art
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Obviousness
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Extensions
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Derivative works
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