| 摘要 |
PURPOSE: To obtain a high density thin optical disc substrate having a favorable accuracy of a plate thickness. CONSTITUTION: On the basis of a value obtained by measuring the plate thickness or weight of an injection-molded or compression-injection-molded optical disc substrate or by measuring the cavity thickness at the injection-molding or compression-injection-molding of the optical disc substrate with cavity thickness measurement equipment 27, the injection speed and injection speed changing-over position of the screw 33 of an injection molding machine or a compression injection molding machine is automatically changed-over. |
