Invalidity dossier
US 6049475
Added 9/21/2026, 9:42:16 AM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US6049475A
Title: Power converting apparatus with drive signal path impedance increasing circuitry
Patent number: US6049475A
Application number: US09/171,708 (filed 1997-03-18)
Publication/grant date: 2000-04-11
Priority date (as listed): 1997-03-18
Inventors: Satoshi Azuma; Akinori Nishihiro; Masakatu Daijyo; Shigemi Kuriyama; Taro Ando
Original/current assignee (as listed): Mitsubishi Electric Corp. (assignment recorded 1999-04-06 to MITSUBISHI DENKI KABUSHIKI KAISHA)
Legal status (as listed): Expired – Lifetime; anticipated expiration 2017-03-18
Classification: H02M1/00 (details of conversion apparatus); H02M1/42 (power-factor compensation/adjustment in converters or inverters)
Prior-art keywords listed: terminal; electric valve; power supply; control means; resistor
Purpose and plain-language scope: The title indicates a power converting apparatus whose drive-signal path includes circuitry that increases impedance. The listed prior-art keywords (terminal, electric valve, power supply, control means, resistor) suggest the apparatus uses electric-valve switching devices controlled by drive signals routed through resistive/impedance elements from a control means and power supply. Beyond the title, keyword list, and classification, the supplied excerpt does not include the abstract, claims, or description, so the specific circuit topology, the conditions under which impedance is increased, and the technical problem solved cannot be stated from this text.
Source: https://patents.google.com/patent/[US6049475](/patent/US6049475)/en
What the excerpt does not establish: The excerpt contains no claim language, abstract, or detailed description. It does not establish the precise scope of the claimed invention, the number or content of claims, the embodiments disclosed, the cited prior art references, or the specific mechanism by which drive-signal path impedance is increased. It also does not establish inventorship disputes, ownership changes beyond the recorded assignment, validity, enforceability, or litigation. All dates and statuses above are reproduced as listed by the source, which itself notes that priority dates and legal status are assumptions, not legal conclusions.
Generated 10/1/2026, 10:01:56 PM
Cases on file (0)
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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.