| 摘要 |
PURPOSE:To decrease the eccentricity of a disk substrate and to decrease the erroneous reading and erroneous recording of information by providing a groove between the inner circumference of the disk substrate and the inner-most circumference of a guiding groove for tracking, providing a projection to fit in the groove at center fittings, fitting the groove and the projection and fitting center fittings at the disk substrate. CONSTITUTION:Between the inner circumference of a disk substrate and the inner-most circumference of the guiding groove for tracking, a groove is provided, a projection to fit in the groove is provided at center fittings, the groove and the projection are fitted in and the center fittings are fitted at a disk substrate. For example, a disk substrate 3 to provide a groove 2A with a radius 26mm, a width 1mm and a depth 0.5mm is stuck with an adhesives layer 6, a projection 2B to fit into the groove 2A is provided at center fittings 1, the groove 2A and the projection 2B are fitted in and the center fittings 1 are fitted at the disk substrate 3. Thus, the optical type information recording disk is obtained in which the eccentricity of the disk substrate is decreased and the erroneous reading and erroneous recording of information are decreased. |
