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. 26, 2011
Filed:
Nov. 21, 2008
Nobuaki Orita, Tokyo, JP;
Yasuhiro Naka, Tokyo, JP;
Nobuaki Orita, Tokyo, JP;
Yasuhiro Naka, Tokyo, JP;
The Furukawa Electric Co., Ltd., Tokyo, JP;
Abstract
A glass substrate for a magnetic disk satisfies Ra≦0.8 [nm], 0 [nm]≦Ra−Ra≦0.2 [nm], Wa≦0.6 [nm], and 0 [nm]≦Wa−Wa≦0.2 [nm]. Rais an average surface roughness of a first annular area between 1 mm and 3 mm outward from an inner periphery of a main surface of the glass substrate, Rais an average surface roughness of a second annular area between 1 mm and 3 mm inward from an outer periphery of the main surface, Wais an average waviness of the first area in a circumferential direction of the glass substrate having a cycle of 300 μm to 5 mm, and Wais an average waviness of the second area in the circumferential direction having a cycle of 300 μm to 5 mm.