Telephone line interface circuit with voltage switching
CA 2105376 C · Owner: Nortel Networks Limited · Inventors: Rosch, Reinhard Werner; Rosenbaum, Stanley Daniel; Sutherland, Brian A.F.S.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A two-wire telephone line interface circuit comprises a driver circuit (10) for supplying direct current on the line (13) a, controlled voltage generator (14), a sensing circuit (12) for monitoring the line current a control circuit (15) for controlling an output voltage (CV) or the voltage generator and a switching circuit (11). The control circuit controls the switching circuit to supply as a supply voltage (DV) for the driver circuit a battery voltage (BV) in an on-hook state of the line or the controlled output voltage of the voltage generator in an off-hook state of the line this output voltage being controlled to provide off-hook current limiting. The control circuit also controls the …
Read 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
- Filed April 3, 1992 and granted February 18, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 3, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 3, 2014.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
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.