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:
Jun. 10, 2003
Filed:
Mar. 01, 2001
Hiroki Yamamoto, Hitachi, JP;
Takashi Namekawa, Hitachi, JP;
Takashi Naito, Hitachiohta, JP;
Yasutaka Suzuki, Jyuou-machi, JP;
Akira Kato, Odawara, JP;
Noriyuki Takeo, Yamakita-machi, JP;
Kiyoshi Akamatsu, Yokohama, JP;
Youichi Inomata, Odawara, JP;
Masatomo Terakado, Mobara, JP;
Ken Takahashi, Tokai-mura, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A glass substrate for a magnetic disk contains a transition metal. The substrate, which is subjected to formation of zone texturing by irradiating the substrate with a laser beam, has a high mechanical strength even if it is not chemically strengthened. The glass substrate contains a transition metal element and has a transmittance of 10% or less for light in a wavelength range of 300 to 2000 nm. The surface roughness of an information recording surface portion thereof is 2.0 nm or less. In addition to a transition metal element, the glass substrate may include a rare earth metal element.