Invalidity dossier
US 6120135
Printhead having heating element conductors arranged in spaced apart planes and including heating elements having a substantially constant cross-sectional area in the direction of current flow
Current assignee: Funai Electric Co Ltd
Added 9/23/2026, 8:51:49 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 6,120,135 A
Title: "Printhead having heating element conductors arranged in spaced apart planes and including heating elements having a substantially constant cross-sectional area in the direction of current flow"
Assignee / Inventors: Originally assigned to Lexmark International, Inc.; later reassigned (2013) to FUNAI ELECTRIC CO., LTD. Inventors: Ashok Murthy and Steven Robert Komplin.
Key Dates: Priority/filing date 1997-07-03 (Application No. US08/887,583); granted/publication date 2000-09-19. Legal status listed as "Expired – Lifetime" (anticipated expiration 2017-07-03).
Purpose: The invention relates to ink jet printheads with a heater chip carrying heating elements (resistors) and conductors that deliver energy to them. In drop-on-demand thermal ink jet printers, resistors are individually addressed with an energy pulse to vaporize ink and form a bubble that expels a droplet. The patent addresses reducing the number of first conductors and associated bond pads without resorting to decoder circuitry, which the text describes as expensive and undesirable.
Plain-language scope: A heater chip is provided with a plurality of first and second conductors arranged in spaced-apart planes and/or in a matrix. Heating elements sit between vertically spaced-apart first and second conductors. The heating elements may be portions of one or more heating element sections or of a blanket of resistive material. The first and second conductors may directly contact the heating elements, or a current transfer layer may be interposed between the heating elements and the first conductors. The heating elements preferably have a substantially constant cross-sectional area along a first axis substantially parallel to the direction of current flow between the first and second conductors. First and second conductors extend between bond pads and resistors, with current delivered via traces, bond pads, and conductors.
Not established by this excerpt: The full text of the claims, dependent claim limitations, the detailed description and figures, the specific prior-art references cited, and any prosecution history. The reassignment and expiration entries are taken from the source's bibliographic data and are not independently verified here.
Generated 10/1/2026, 9:41:06 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
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.