Expired Canadian patentCanada
Telephone call loudspeaker monitoring and relay control circuit
CA 993128 A · Owner: Nippon Tsu Shin Kogyo K.K. · Inventors: Kerman, Stephen E.; Gotoh, Kazuyuki; Ichikawa, Mikihiro
Overview
Drawings and full text
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordRead the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted July 13, 1976. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended July 13, 1993.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Filed—
GrantedJuly 13, 1976
Term endedJuly 13, 1993
Patent numberCA 993128 A
Classification (IPC)H04M1/60
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.