Hands-free telephone
CA 2225203 C · Owner: Shiraki, Koichi · Inventors: Shiraki, Koichi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention provides a hands-free telephone wherein near-end caller voice detection information is provided with little error, and wherein electric power saving effects are improved, and also wherein the far-end caller does not receive an unnatural impression. An echo canceller comprises: level calculating means 1 2, and 3, for calculating the level of reception signals input, transmission signals, and residual signals; and adaptive filter 4 for inputting the reception signals and transmission input signals and outputting residual signals; echo cancellation amount calculation means 5 for calculating the echo cancellation amount from the input transmission signal level and residual …
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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 18, 1997 and granted January 22, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 18, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 18, 2019.
- 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.