GLASS SUBSTRATE FOR MAGNETIC DISK AND MAGNETIC DISK

The purpose of the present invention is to provide a glass substrate for magnetic discs, said glass substrate enabling to improve yield. This disc-like glass substrate for magnetic discs has a main surface, a circular hole at a center section, and an inner circumferential-side surface section on the...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser:	Kara YOSHIDA, Shigeki TAKANO, Masabumi ITO
Format:	Patent
Sprache:	eng
Schlagworte:	INFORMATION STORAGE INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER PHYSICS
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Beschreibung
Zusammenfassung:	The purpose of the present invention is to provide a glass substrate for magnetic discs, said glass substrate enabling to improve yield. This disc-like glass substrate for magnetic discs has a main surface, a circular hole at a center section, and an inner circumferential-side surface section on the center section side. The arithmetic average roughness Ra of the inner circumferential-side surface section is equal to or less than 0.7 nm, and the value of (Ra_deg_max)-(Ra_deg_min) in a predetermined region of the inner circumferential-side surface section is not less than 0.15 nm but not more than 1.0 nm.