| 摘要 |
PROBLEM TO BE SOLVED: To provide a glass substrate for an information recording medium provided as a base body of a magnetic recording medium wherein operation of a magnetic head at an outer peripheral end part is stabilized especially in a LUL (Load Unload) system. SOLUTION: In the glass substrate for the information recording medium, a position R1 and a position R2 apart from the position R1 by a fixed interval in a direction to an outer peripheral end surface are determined on a contour on the same principal surface side of a cross section vertical to the principal surface in a radial direction of the glass substrate, the contour descends on the substrate side from the position R1 to the position R2, the descending contour has one inflection point between positions R1 and R2, the maximum angleθ1 formed by a first tangent tangential to the contour from the position R1 to the inflection point and a reference plane of a flat part of the principal surface as a reference and the maximum angleθ2 formed by a second tangent tangential to the contour from the inflection point to the position R2 and the first tangent satisfy a certain conditional expression and the contour from the position R2 in the direction to the outer peripheral end surface exists on the substrate side of the reference plane and extends from the reference plane to the outer peripheral end surface. COPYRIGHT: (C)2008,JPO&INPIT
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