Invalidity dossier
US 2475578
Radio and visual warning device
Current assignee: Farnsworth Research Corp
Added 9/24/2026, 1:29:47 AM
Active provider: DeepSeek · deepseek-v4-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 2,475,578
Title: Radio and visual warning device
Patent number: US2475578A
Inventor: William S. Halstead
Original assignee / current assignee (as listed): Farnsworth Research Corp
Application number: US576769A
Filing / priority date: 1945-02-08
Publication (grant) date: 1949-07-05
Legal status (as listed): Expired – Lifetime; anticipated expiration 1966-07-05
Classification (as listed): B61L23/00 — Control, warning or like safety means along the route or between vehicles or trains
Purpose (from the supplied text): The invention "pertains to a radio signaling device, and more particularly to a device wherein a radiotelephone in combination with visual signaling means is provided." It is described as a portable combination radiotelephone and electric spotlight or lantern, the spotlight being capable of automatically flashing synchronously with a radio-emitted tone signal. Stated uses include vehicles such as trains or automobiles, and use by individuals on the ground; described applications include warning an approaching locomotive engineer, two-way radiotelephone communication after the warning signal, mounting on the last car of a train with remote control, and a parabolic radio wave reflector directing signals rearwardly. The spotlight may also produce a constant beam for general illumination.
Plain-language scope (from the supplied text): The disclosure describes a portable unit combining a radio transmitter and receiver with a pulsing visual signal, so that a pulsing radio tone and a flashing light are emitted together and in synchronism; a receiver of a second similar unit may receive the tone. A described feature is a transmitter lockout relay that suspends automatic pulse transmission while a carrier signal is received from another transmitter, while activating a visual and/or audible calling signal. Figures listed include a block diagram (Fig. 6), a schematic circuit diagram (Fig. 7), and a system block diagram including a lockout relay (Fig. 10).
What the excerpt does not establish: It is an excerpt only; the full specification, complete claims, and all drawing content are omitted (explicitly noted: "[Excerpt only; consult the source for omitted text.]"). Accordingly, no claim language, claim scope, or claim count can be verified here. No litigation, ownership-transfer, validity, or prior-art conclusions are drawn.
Generated 10/1/2026, 9:31:23 PM
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Litigation summary
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Proceedings on file (0)
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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
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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.