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. 20, 2009
Filed:
Apr. 20, 2006
Masamichi Kezuka, Osaka, JP;
Koji Okuhata, Osaka, JP;
Kensuke Matsuno, Osaka, JP;
Takeo Watanabe, Osaki, JP;
Masamichi Kezuka, Osaka, JP;
Koji Okuhata, Osaka, JP;
Kensuke Matsuno, Osaka, JP;
Takeo Watanabe, Osaki, JP;
Nippon Sheet Glass Co., Ltd., Osaka, JP;
Hoya Corporation, Tokyo, JP;
Abstract
A substrate for use as a disk substrate in a hard disk drive or the like, an information recording medium such as a magnetic disk, and a starting material glass plate which is a starting material of the substrate for information recording media. The forming conditions of the starting material glass plate are controlled such that the starting material glass plate has a long-wavelength waviness of not more than 6 nm. This starting material glass plate is polished so as to have a long-wavelength waviness of not more than 6 nm using CeOabrasive grains having a mean grain diameter of not less than 0.01 μm and a 90% diameter of the volume grain size distribution of not less than 0.02 μm. The resulting substrate for an information recording medium has an excellent planarity, can be obtained in a short time and with a low polishing amount, and the resulting information recording medium is able to cope with increased data zone recording density.