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:
Aug. 17, 2021
Filed:
Mar. 28, 2019
Hoya Corporation, Tokyo, JP;
Takeyoshi Takahashi, Akishima, JP;
Masaaki Ueda, Yokohama, JP;
HOYA CORPORATION, Tokyo, JP;
Abstract
A hard disk drive includes a doughnut-shaped magnetic-disk substrate having a circular hole provided in the center. The doughnut-shaped magnetic-disk substrate includes a pair of main surfaces, and an outer circumferential end surface and an inner circumferential end surface each including a side wall surface and a chamfered surface that is formed between each main surface and the side wall surface. A measurement point is provided on the outer circumferential end surface every 30 degrees in the circumferential direction with reference to a center of the substrate, and when a curvature radius of a shape of a portion between the side wall surface and the chamfered surface is determined at each measurement point, a difference in the curvature radius between neighboring measurement points is 0.01 mm or less.