Low tar retention filter
CA 2502587 C · Owner: Essentra Filter Products Development Co. Pte. Ltd. · Inventors: Clarke, Paul Francis
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A tobacco smoke filter which has a tar retention of at most 50% and comprises a , relatively high draw resistance downstream filtering plug (2) of at most 50% tar , retention, a relatively low draw resistance upstream filter plug (3) of at most 22% , tar retention spaced longitudinally upstream therefrom and a filter wrapper , (4) , engaging around and joining the spaced plugs to define a cavity (6) therebetween.
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 October 13, 2003 and granted January 24, 2012. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended October 13, 2023.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 13, 2025.
- 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.