| 摘要 |
PROBLEM TO BE SOLVED: To provide an information recording disk of a small diameter, which has a structure capable of holding a hub in an inner peripheral part, prevents double refraction due to the generation of the stress in a substrate and decreases reading errors. SOLUTION: In the information recording disk which has a columnar recessed part housing the hub in the central part of a disk-shaped substrate and a hole to be inserted with a spindle, formed in the base surface of the recessed part coaxially with the substrate, an information recording region of the innermost periphery is provided in a region of <=16 mm in radius and the substrate in the information recording region has 0.3-0.1 mm thickness. Annular recessed parts are formed at least at one point between the information recording region and the recessed part coaxially with the substrate so as to have thickness equal to or lower than 75% thickness of the substrate in the information recording region. |
