Invalidity dossier
US 4680859
Thermal ink jet print head method of manufacture
Current assignee: Hewlett-Packard Company
Added 9/17/2026, 12:47:53 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: US4680859A
Title: Thermal ink jet print head method of manufacture
Patent Number: US4680859A
Application Number: US06/915,292
Inventor: Samuel A. Johnson
Original Assignee: Hewlett Packard Co (Current Assignee listed as HP Inc)
Prior Art Date: 1985-12-06
Filing Date: 1986-10-03
Publication/Grant Date: 1987-07-21
Legal Status: Expired – Lifetime (anticipated expiration 2005-12-06)
Source: https://patents.google.com/patent/[US4680859](/patent/US4680859)/en
Purpose
The invention relates generally to thermal ink jet printing and, more particularly, to a new and improved thermal ink jet printhead assembly. The stated general purpose is to provide a printhead assembly that eliminates problems associated with using drilled holes through a common printhead substrate member—specifically, the special routing of conductive leads and the reduced packing density such channels require.
Plain-Language Scope
A single elongated slot is cut in the substrate to supply ink to multiple ink reservoirs associated with resistive heater elements formed above the substrate's top surface. These heater elements are spaced around the slot's periphery at predetermined distances. Conductive leads are provided between each resistive heater element and external electrical connections, with a barrier layer and orifices formed above. The disclosed subject matter also concerns a method of manufacture.
What the Excerpt Does Not Establish
The supplied text is explicitly marked as an excerpt; omitted text includes portions of the description and the full claims. Accordingly, this overview cannot confirm claim scope, claim count, or claim language. The defining "Definitions" section is partial, and no independent claims are quoted in the source provided. The excerpt does not establish validity, enforceability, or the substantive content of any prior art. It also does not establish the accuracy of the listed assignees or legal status, which the source itself characterizes as assumptions or unverified listings. Litigation references appear in the source but are outside this overview's scope.
Generated 10/1/2026, 10:03:22 PM
Cases on file (1)
Group view →Specific litigation cases in our database that name US patent 4680859. The free-form analysis below may also discuss cases beyond this list.
- Hewlett-Packard Company v. Microjet Technology Co., Ltd. et al.filed Dec 22, 2000337-TA-446U.S. International Trade Commissionterminated Apr 25, 2002terminated
Defendants: Microjet Technology Co., Ltd., Printer Essentials.com, Inc., Price-Less Inkjet Cartridge Company, and 2 others
Other patents asserted: 4635073, 4827294, 4872027, 4992802, 5409134
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
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 (1)
1 tracked lawsuit name US 4680859.