Expired Canadian patentCanada
Signalling device positively controlled by direct current and employing circuits comprising magnetic cores
CA 880552 A · Owner: Societa Italiana Telecommunicazioni Siemens S.P.A. · Inventors: Franco De Marco; Alberto Ciaccia
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 September 7, 1971. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended September 7, 1988.
- 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—
GrantedSeptember 7, 1971
Term endedSeptember 7, 1988
Patent numberCA 880552 A
Classification (IPC)H04L
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.