Slope detection method, and information detection/writing apparatus using the method
CA 2055852 C · Owner: Kawagishi, Hideyuki · Inventors: Tagawa, Masahiro; Yamamoto, Keisuke; Takeda, Toshihiko
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Disclosed is a method of detecting a slope of a surface of an information record medium in an apparatus for detecting/writing information using one or a plurality of probes from/in the information record medium comprising, scan step of scanning the surface of the information record medium using the probe information, detection step of detecting information from the surface of the information record medium through said probe when the scan step is executed; and slope detection step of detecting the slope of the surface of the information record medium on the basis of the information detection result.
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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 November 19, 1991 and granted September 22, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 19, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 19, 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
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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.