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:
Oct. 30, 1990
Filed:
Jun. 27, 1989
Applicant:
Inventors:
Ikue Kawashima, Sendai, JP;
Futoyoshi Koh, Sendai, JP;
Masafumi Kumano, Sendai, JP;
Shinei Ryu, Sendai, JP;
Assignees:
Ricoh Company, Ltd., Tokyo, JP;
Ricoh Research Institute of General Electronics Co., Ltd., Miyagi, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
428694 ; 428611 ; 428900 ;
Abstract
A perpendicular magnetic recording medium is disclosed, which comprises a substrate, a soft magnetic layer formed on the substrate, a lower recording layer having a coercive force of Hcl formed on the soft magnetic layer, and an upper recording layer having a coercive force of Hcu, with the coercive ratio of Hcu/Hcl being in the range of 1.4 to 3.3, that is, 1.4.ltoreq.Hcu/Hcl.ltoreq.3.3.
Kawashima, Ikue. (1990). Perpendicular magnetic recording medium (U.S. Patent No. 4966821). U.S. Patent and Trademark Office. https://idiyas.com/patent/badge/4966821
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile