Current limit circuit for ringing amplifier
CA 2004690 C · Owner: Mitel Corporation · Inventors: Lavrisa, Thomas V.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A current limit circuit for a ringing amplifier in a telephone system comprised of circuitry connected to the output of an error amplifier for receiving and comparing the output ringing current to a pair of predetermined threshold levels and in response clipping the error signal output from the error amplifier to a certain level, thereby clipping the error signal amplitude at levels to maintain the current below the threshold level. A capacitor is connected to the output of the current limit circuit for storing the final value of the current limiting error signal and using the final value as the starting value of the next output ringing signal sinusoidal peak of the same polarity.
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 December 6, 1989 and granted April 5, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 6, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 6, 2011.
- 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.