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Telephone signaling system

US 2,278,504 A · Inventors: WINGARDNER CHARLES A

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Listed from its USPTO record in Patent Yard's full-term archive. Its claims, description and drawings are in the USPTO PDF and on Google Patents, and the Claude kit works from them.

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Why it's free to use

  • Granted April 7, 1942. A patent granted before 1976 lasted at most 17 years from grant, so its term ended by April 7, 1959.
  • We check US rights only. Old patents can still inspire new ones: improvements may be patentable.
FiledMarch 8, 1941
GrantedApril 7, 1942
Term endedApril 7, 1959
Application number—
Classification (CPC)—
Length3 pages

Timeline

Timeline From USPTO dates

194219441946194819501952195419561958Application filedMarch 8, 1941Patent grantedApril 7, 1942Term endedApril 7, 1959

Sources & verification

Official USPTO records

Full published documentText and every drawing sheet as a PDF.USPTOFile historyStatus, office actions, notices, fee records and petitions.USPTO Patent CenterPatent Public Search recordSearchable full text and bibliographic data.USPTO

Cross-check elsewhere

Google PatentsFull text, worldwide family, citing patents and legal events.patents.google.comJustia PatentsFull text, claims and classification.patents.justia.comFreePatentsOnlineFull text and PDF.freepatentsonline.comEspacenetForeign family and legal status.European Patent Office

Everything on this page comes from the USPTO record linked above.