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:
Nov. 27, 2001
Filed:
Apr. 15, 1997
Applicant:
Inventors:
Assignee:
NEC Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B 7/24 ; B32B 3/00 ;
U.S. Cl.
CPC ...
G11B 7/24 ; B32B 3/00 ;
Abstract
An optical disk includes at least two information recording layers on one side of the disk and at least the first information recording layer from the light incident side is of an erasable type formed with a material such as bismuth-substituted magnetic garnet or cobalt ferrite which has an extinction coefficient, a coefficient of an imaginary part of a complex index of refraction, being not more than 1.0, but not less than 0.5, and gives a large magneto-optic effect and a small light absorptivity.