Patent ID: 8930974
Filing Date: 2015-01-06
Classification: G11B

Abstract:
1. A disk-shaped information recording medium having an outer diameter and an inner diameter, the information recording medium comprising: a substrate having a predetermined thickness; a first side that is one side of the substrate; a second side that is the other side of the substrate; a cylindrical portion forming a through hole formed at a center of the substrate; a thin portion formed so as to surround an outer diameter of the cylindrical portion, the thin portion being thinner than the predetermined thickness; a non-inclined surface formed at the thin portion; an inclined surface formed on an outer diameter side of the non-inclined surface at the thin portion, the inclined surface being inclined at a predetermined angle to the non-inclined surface and being larger than the non-inclined surface in the thin portion; and a curvature portion formed between the non-inclined surface and the inclined surface.