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. 01, 2019
Filed:
Feb. 24, 2017
Applicant:
Hoya Corporation, Tokyo, JP;
Inventors:
Masanori Tamaki, Higashimurayama, JP;
Takeyoshi Takahashi, Akishima, JP;
Masaaki Ueda, Yokohama, JP;
Assignee:
HOYA CORPORATION, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B 5/82 (2006.01); G11B 5/73 (2006.01); G11B 5/84 (2006.01);
U.S. Cl.
CPC ...
G11B 5/82 (2013.01); G11B 5/7315 (2013.01); G11B 5/8404 (2013.01);
Abstract
A magnetic-disk glass substrate has a circular hole at a center, and includes a pair of main surfaces and a side wall surface orthogonal to the main surfaces. A roundness of the circular hole is 1.5 μm or less. A difference between a maximum value and a minimum value of radii of three inscribed circles that are respectively derived from outlines in the circumferential direction at three positions spaced apart by 200 μm in a substrate thickness direction on the side wall surface of the circular hole is 3.5 μm or less.