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:
Feb. 07, 1984
Filed:
Nov. 12, 1980
Applicant:
Inventors:
Nobuo Nakagawa, Yokohama, JP;
Yoshiki Kato, Tokyo, JP;
Katsuo Abe, Yokosuka, JP;
Takao Edamura, Yokohama, JP;
Takao Nakamura, Yokohama, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
B21C / ;
U.S. Cl.
CPC ...
428579 ; 204 / ; 204 42 ; 427131 ; 360135 ; 428 64 ; 428 65 ; 428216 ; 428409 ; 428411 ; 428412 ; 4284258 ; 428469 ; 428629 ; 428636 ; 428654 ; 428651 ; 428653 ; 428656 ; 428660 ;
Abstract
A base plate for magnetic recording disc is produced by coating thin metal layers containing no impurities for forming defects by an anodizing treatment on one or both sides of a discoid substrate made of a metal such as aluminum or an aluminum alloy or from a plastic by a dry process, and anodizing the thin metal layers so as to form anodized film from the surfaces of the thin metal layers to a certain depth while the portions contacting to the substrate are retained not anodized.