| 摘要 |
PURPOSE:To eliminate the need for deburring the recording layer forming surface side and to prevent the damage of a recording layer by forming an incline on a disk substrate so that the diameter of the side of the disk on which a recording layer is formed is made smaller and notching the outer peripheral edge of the side on which the recording layer is not formed. CONSTITUTION:An incline 4 is formed on a disk substrate 1 so that the disk diameter is progressively decreased from the side 1a on which a recording layer is not formed toward the side 1b on which a recording layer is formed. A horizontal burr 5 projecting toward the outer periphery along the side 1b and a vertical burr 6 vertically projecting from the outer peripheral edge of the side 1a are formed on the substrate 1 prepared by injection molding, the horizontal burr 5 is left as such, the vertical burr 6 is removed by obliquely notching the outer peripheral edge of the side 1a, and the tip of the burr is placed within the outer most peripheral edge of the disk determined by the notched part and the incline. Consequently, the recording layer is not damaged. |
