Screw
CA 2225056 C · Owner: Chen, Sen-Yang · Inventors: Chen, Sen-Yang; Cheng, Chao-Tai
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The shank portion of a screw has a surface formed with a screw thread throughout the length thereof and a lower section formed with a flute at the surface thereof. The flute extends from a tip of the shank portion and has a longitudinal length which is inclined with respect to a longitudinal axis of the shank portion. The flute is defined by a planar side wall which is inclined relative to the longitudinal axis and a curved bottom. The planar side wall has a surface with screw thread portions that are disposed in a staggered arrangement in a direction receding from a direction of screw advancing rotation. The flute has a depth which decreases gradually from the tip of the shank portion, and …
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 17, 1997 and granted October 16, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 17, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 17, 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.