Invalidity dossier
US 6234598
Shared multiple terminal ground returns for an inkjet printhead
Current assignee: Hewlett-Packard Company, Hewlett-Packard Development Company, L.P.
Added 9/24/2026, 12:49:04 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 — US6234598B1
Title: "Shared multiple terminal ground returns for an inkjet printhead"
Patent number / application: US6234598B1 (application US09/386,574)
Inventors: Joseph M. Torgerson, Rama Prasad, Todd A. Cleland, Dale R. Oughton
Assignee (per source): Original assignee Hewlett Packard Co; current assignee listed as Hewlett Packard Development Co LP. The source notes Google "has not performed a legal analysis" and does not warrant the listed assignees.
Key dates (as listed): Priority/filing date 1999-08-30; publication/grant date 2001-05-22; anticipated expiration 2019-08-30; status "Expired - Lifetime."
Foreign family members identified in the text: DE60015676T2, EP1520702B1, EP00306763A / EP1080903B1, JP2000260315A / JP2001080074A. The source also displays a "Family has litigation" link to an external Darts-ip dataset; per instructions, that is not analyzed here.
Purpose and plain-language scope (from the supplied text): The invention concerns ground returns for an inkjet printhead, specifically sharing multiple ground return terminals. Classifications place it in inkjet printing, particularly bubble-jet printheads, resistive heater elements, printhead layer structure, and electrical connections between chip and the outside (B41J2/14072), with related control-circuit classifications covering power-line sections, switching sections, and controlling heads based on heating elements forming bubbles. The prior-art keywords listed are "group," "substrate," "heater," "printhead," and "electrical."
What the excerpt does not establish: The supplied text is largely bibliographic and classification data plus an image-heavy page; it does not include the claims, abstract, detailed description, or drawings. Accordingly, this overview cannot state the specific claimed structure, the number or arrangement of shared ground terminals, the independent/dependent claim set, the exact problem solved, or any measured benefits. It also cannot confirm inventorship, claim scope, or the accuracy of the litigation, reassignment, or legal-status metadata, which the source itself labels assumptions or non-legal analyses. No prior art or validity assessment is made.
Source: https://patents.google.com/patent/[US6234598](/patent/US6234598)/en
Generated 10/1/2026, 9:31:46 PM
Cases on file (2)
Group view →Specific litigation cases in our database that name US patent 6234598. The free-form analysis below may also discuss cases beyond this list.
- Hewlett-Packard Company et al. v. MicroJet Technology Co., Ltd. et al.filed May 25, 2010337-TA-723U.S. International Trade Commission, Washington, D.C.terminated Oct 24, 2011Violation found; general exclusion order issued; investigation terminated
Defendants: MicroJet Technology Co., Ltd., Asia Pacific Microsystems, Inc., Mipo Technology Limited, and 4 others
Other patents asserted: 6481817, 6309053, 6398347, 6402279, 6412917
- Hewlett-Packard Company v. MicroJet Technology Co., Ltd. et al.filed Mar 5, 2010337-TA-711U.S. International Trade CommissionInstituted; '817 inclusion probable but unverified
Defendants: MicroJet Technology Co., Ltd., Mipo Technology Limited, Mipo Science & Technology Co., Ltd., and 3 others
Other patents asserted: 6481817, 6309053, 6398347, 6402279, 6412917
Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
Current assignee: Hewlett-Packard Company, Hewlett-Packard Development Company, L.P.
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.
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This patent in court (2)
2 tracked lawsuits name US 6234598.