The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 21, 1997
Filed:
Jul. 27, 1994
Yoichi Osato, Yokohama, JP;
Katsumi Miyata, Tokyo, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A magnetooptical recording medium has first and second magnetic layers laminated in that order on a transparent substrate on which a received laser beam is incident. The coercive force of the second magnetic layer is greater than that of the first magnetic layer and is greater than .sigma..sub.w /2M.sub.s2 h.sub.2, where .sigma..sub.w is the magnetic wall energy between the first and second magnetic layers, M.sub.s2 is the saturation magnetization of the second magnetic layer, and h.sub.2 is the film thickness of the second magnetic layer. The coercive force of the first magnetic layer is greater that .sigma..sub.w /2M.sub.s1 h.sub.1, where M.sub.s1 is the saturation magnetization of the first magnetic layer and h.sub.1 is the film thickness of the first magnetic layer. The compensation temperature of the first magnetic layer is smaller than the Curie temperature of the first magnetic layer. Recording is performed by selectively applying a laser spot, having either a high power or a low power.