| 摘要 |
PURPOSE:To prevent a C/N at an inner peripheral side from being lowered and to perform satisfactory recording and reproduction by providing a part where no bonding agent is filled at the inner peripheral side of a disk. CONSTITUTION:On the substrate 1 of the disk, a protection layer 2, a recording layer 3, a protection layer 4, a bonding layer 5, and polycarbonate 6 same as the substrate 1 are formed and laminated. And a gap 7 in which no bonding agent is filled is provided outside the center hole 8 of the disk. As a result, double refraction at the inner peripheral side of the substrate 1 can be suppressed at minimum even when the heat of a spindle motor is increased, and the lowering of the C/N at the inner peripheral side of the disk in use can be prevented from occurring. |
