| 摘要 |
PURPOSE:To prevent damages of substrates when substrates are stacked so that no spacer is necessary for storage of substrates by injection molding a substrate in a manner that the outer edge of the substrate is thicker than other area and thickness of the substrate changes continuously without giving no step on the surface of the substrate. CONSTITUTION:The optical disk substrate made of polycarbonate has a flat surface where guide grooves 2 are formed, while on the back surface, thickness is continuously changed to increase from outer line of the groove area 3 and mirror area 4 to the outer edge. Thereby, when substrates are stacked, scratches or rubbing on the surfaces can be prevented. These substrates can be stacked and stored without using spacers or the like. |
