MAGNETIC-DISK GLASS SUBSTRATE AND MAGNETIC DISK

摘要

A magnetic-disk glass substrate according to the present invention is a doughnut-shaped magnetic-disk glass substrate having a circular hole provided in the center, a pair of main surfaces, and an outer circumferential end surface and an inner circumferential end surface each including a side wall surface and a chamfered surface that is formed between each main surface and the side wall surface. A measurement point is provided on the outer circumferential end surface every 30 degrees in the circumferential direction with reference to a center of the glass substrate, and when a curvature radius of a shape of a portion between the side wall surface and the chamfered surface is determined at each measurement point, the difference in the curvature radius between neighboring measurement points is 0.01 mm or less.

主权项

1. A doughnut-shaped magnetic-disk glass substrate having a circular hole provided in the center, the doughnut-shaped magnetic-disk glass substrate comprising:
a pair of main surfaces; and an outer circumferential end surface and an inner circumferential end surface each including a side wall surface and a chamfered surface that is formed between each main surface and the side wall surface, a measurement point being provided on the outer circumferential end surface every 30 degrees in the circumferential direction with reference to a center of the glass substrate, and when a curvature radius of a shape of a portion between the side wall surface and the chamfered surface is determined at each measurement point, a difference in the curvature radius between neighboring measurement points being 0.01 mm or less.