Noise reducing system
CA 2076390 C · Owner: Noise Cancellation Technologies Inc. · Inventors: Ross, Colin Fraser; Langley, Andrew John; Eatwell, Graham Paul
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An active control system for attenuating tonal noise in a defined region is described. In its most basic form the system includes sensors (1, 8) for generating signals indicative of the residual noise in the region after attenuation and the uncontrolled sound affecting the region, signal processing circuits (10 26) for processing the generated signals differently depending on the tonal content thereof, an adaptive filter (5) supplied with at least one of the generated signals whose characteristic is controlled by the processing circuitry (10), a transducer (6) for producing tonal-noise-attenuating disturbance in the region and delay means (4) for delaying signals relating to the …
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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 February 20, 1991 and granted July 14, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 20, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 20, 2013.
- 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.