Tobacco smoke filters
CA 1191065 A · Owner: Brown & Williamson Tobacco Corporation · Inventors: Luke, John A.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A smoke filter for a smoking article (e.g. a cigarette) comprises a filter plug having an airflow duct whose floor extends along the filter plug from the mouth end of the plug such that the end of the duct remote from the mouth end is deeper than the end of the duct at the mouth end, with a region of progressively decreasing depth from the deep end towards the shallow end. The at least one duct may comprise a plurality of grooves equiangularly spaced around the periphery of the filter plug, in which case it is possible for the grooves to extend helically and to be divided into sets of opposite hand such that each groove of one set intersects several grooves of the other set. Alternatively …
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
- Granted July 30, 1985. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended July 30, 2002.
- 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.