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:
Jul. 18, 1989
Filed:
Dec. 16, 1987
Applicant:
Inventors:
Kenji Uchiyama, Nagano, JP;
Hideki Ishizaki, Nagano, JP;
Hajime Utsunomiya, Nagano, JP;
Suguru Takayama, Nagano, JP;
Assignee:
TDK Corporation, Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
428694 ; 428469 ; 428472 ; 428698 ; 428699 ; 428702 ; 428704 ; 428900 ;
Abstract
An optical recording medium comprising a recording layer on a substrate and a protective layer formed adjacent to the upper and/or lower surface of the recording layer is more durable and corrosion resistant when the protective layer has a composition comprising, in % by weight, 40-60% of SiO.sub.2, 0.5-10% of an alkali metal oxide, 10-59.5% of Al.sub.2 O.sub.3 and/or B.sub.2 O.sub.3, and optionally up to 50% of a divalent metal oxide.