Patent ID: 7989099
Filing Date: 2011-08-02
Classification: G11B

Abstract:
1. An information medium substrate that is formed as a flat plate and comprises: an information region formed on one surface of the information medium substrate, the one surface of the information medium substrate being formed with a light transmitting layer so as to cover the information region; a first convex part formed on the one surface of the information medium substrate in a region between a rim part of a center hole and an inner circumferential edge of the information region; and a second convex part formed on another surface of the information medium substrate at a position that overlaps a protruding end part of the first convex part in a thickness direction of the information medium substrate, the another surface of the information medium substrate opposing the one surface of the information medium substrate, wherein: the entire region outside the first convex part on the one surface of the information medium substrate is formed smooth, a third convex part is formed in a region outside the information region on the another surface, the first convex part is formed higher than a recording layer that is formed in the information region, the first convex part and the second convex part are integrally formed with the information medium substrate, and an information region is not formed on the another surface of the information medium substrate.