Expired, full termArchiveSolo inventor
Telephone system
US 1,523,402 A · Inventors: CLARK EDGAR H
Overview
1 drawing sheet
Every sheet is in the USPTO PDF.
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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.
Why it's free to use
- Granted January 20, 1925. A patent granted before 1976 lasted at most 17 years from grant, so its term ended by January 20, 1942.
- We check US rights only. Old patents can still inspire new ones: improvements may be patentable.
FiledFebruary 7, 1919
GrantedJanuary 20, 1925
Term endedJanuary 20, 1942
Application number—
Classification (CPC)H04Q3/00
Length4 pages
Sources & verification
Official USPTO records
Cross-check elsewhere
Everything on this page comes from the USPTO record linked above.