Recessed screw
CA 2108743 C · Owner: Shinjo, Katsumi · Inventors: Shinjo, Katsumi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A recessed screw has a recess (12) formed in the head of screw, and the recess is defined as a superimposition of two equilaterally-triangular bores (14) which each have vertices (13) shaped arcuate and are arranged coaxially with a phase shift of 60° around the screw axis. The recess thus has alternating six grooves (15) and six driven vanes (16) having side walls (16a) extending parallel with the axis, and an inner ridge of vane is a conically curved sticking wall (18) inwardly slanted towards a bottom (17) of the recess (12). The cross-sectional area (A) of groove (15) is larger than that (B) of each vane (16). A driver bit (25) has six driving vanes (27) in conformity with the grooves …
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 19, 1993 and granted October 5, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended October 19, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 19, 2015.
- 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.