Invalidity dossier
US 4938219
Electrocardiographic electrode
Current assignee: Riken Corp
Added 9/23/2026, 4:40:24 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 4938219
Title: Electrocardiographic electrode
Patent number: US 4,938,219 A
Inventors: Hiroyoshi Ishii; Kenzo Suzuki; Misao Kaneko; Hiroshi Kawamoto; Chuji Shimizu; Yasuaki Onodera
Assignees (original and current): Riken Corp; Fukuda Denshi Co Ltd
Key dates: Priority date 1987-01-16 (claimed from JP457787U and JP457587U); filing date 1989-10-17 (application US07/423,590); granted/publication date 1990-07-03; anticipated expiration 2008-01-15. Legal status listed as "Expired – Fee Related."
Purpose: To overcome drawbacks of a metal electrode element—excess weight unsuited to skin mounting, high polarization voltage, and complicated, costly, and dangerous silver-plating manufacture—and to eliminate the two clamping members previously needed to hold the expansible member to the electrode element.
Plain-language scope: The claims describe an electrocardiographic electrode with three cooperating parts. First, an electrode element made of synthetic resin, having: a head portion with a lead attached and a straight recessed portion; a neck portion with an engagement portion narrower than the head portion; a straight portion continuous with the head's recessed portion; and a bottom portion broader than and supporting the neck portion, for skin contact. The resin's outer surface is made electrically conductive by coating with metal powder (e.g., silver or an amorphous alloy), which creates surface irregularities that increase effective area. Second, an expansible member that locks onto the neck's engagement portion—its small central hole expands over a sloped conoidal head section and contracts to clamp between head and bottom portions, with no clamping members. Third, an adhesive film with a central opening, secured to the expansible member, holding the electrode against the skin. Optional features include an irregular bottom contact surface and a gel-like electrolyte material with a cover.
Source: https://patents.google.com/patent/US4938219/en
What the excerpt does not establish: The full claim set and their exact language and dependencies, the complete specification and drawing reference numerals, prosecution history, the scope of the incorporated Japanese utility-model applications, and whether any claim limitations were amended.
Generated 10/1/2026, 9:44:19 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
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.