Invalidity dossier
US 5644342
Addressing system for an integrated printhead
Current assignee: Hewlett Packard Development Co LP
Added 9/24/2026, 12:51:02 AM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
US 5,644,342 — "Addressing System for an Integrated Printhead"
- Patent number: US 5,644,342 A
- Inventor: Dimitri Argyres
- Original assignee: Hewlett-Packard Co.; current assignee listed as Hewlett-Packard Development Co. LP
- Priority date: 1993-03-31; application filed: 1995-01-30 (application no. US08/381,008); granted/published: 1997-07-01
- Status listed: Expired – Lifetime (anticipated expiration 2014-07-01)
- Source: https://patents.google.com/patent/US5644342/en
Purpose. The patent addresses thermal inkjet printing—specifically selecting heater resistors in an integrated printhead to eject ink. Conventional two-dimensional multiplexing drives one primitive select line and one address select line to activate a transistor in series with a heater resistor. The stated drawback: as nozzle count and print quality rise, interconnect pad count rises, increasing die and tape automated bonding (TAB) area, drive electronics, and printer flex cost, while reducing reliability and space for ESD protection.
Plain-language scope. The described integrated printhead has an M-row by N-column array of groups of ink jet elements, each group with a unique row and column address. A first addressing control (primitive selects) chooses one of M rows; a second (ground selects) chooses one of N columns; and a third dimension comes from address line selects coupled to elements within each group. One group is addressed by the first and second controls; individual heater-resistor/transistor pairs are selected via the address line selects, so fewer interconnect pads are needed. Embodiments add adjustment resistors between the addressing means to balance energy dissipated across groups, and a layout placing primitive-select and ground-select pads together centrally with heater-resistor/transistor pairs arranged peripherally.
What the excerpt does not establish. The supplied text is marked as an excerpt with omitted content; it provides no claims, no complete figure descriptions, and no prior-art discussion. It cannot support statements about claim scope, prosecution history, validity, infringement, or litigation—none of which were researched here.
Generated 10/1/2026, 9:31:43 PM
Cases on file (0)
Specific litigation cases in our database that name US patent 5644342. The free-form analysis below may also discuss cases beyond this list.
No cases on file mention this patent. Upload a CSV or add a case manually in Admin → Manage litigation cases.
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.
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.