Magneto-optical disk and manufacturing methods thereof
CA 2044427 C · Owner: Sharp Kabushiki Kaisha · Inventors: Nakayama, Junichiro; Ohta, Kenji; Katayama, Hiroyuki
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A magneto-optical disk according to the present invention has a substrate, a recording layer formed on the substrate and an outer layer formed on the recording layer, above which a floating head is hovered. The outer layer is constituted of a protective layer an, antisticking layer for head, having a texture formed on its surface and other layers. The magneto-optical disk is designed such that, when rotated at a constant angular velocity, the thickness of the outer layer is substantially inversely proportional to a radial position r on the magneto-optical disk raised to the 1/2nd power. In the formation of the outer layer a screen whose meshes, become gradually finer from the innermost …
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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 June 12, 1991 and granted February 11, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 12, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 12, 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
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.