| 摘要 |
PURPOSE:To reduce the defective eccentricity and at the same time to improve the working efficiency by dividing the inner circumferential space of a transparent substrate into >=2 pieces. CONSTITUTION:A disk is divided into upper and lower parts and adhered to a glass substrate before production of a pregroup. Thus the center of the disk is coincident with the center of a concentrical pregroup when the pregroup is produced. A recording medium layer is formed on the surface of the substrate containing the pregroup by a vapor deposition process, etc. In assembling a disk, two substrates are bonded together with coincidence secured between both centers. Thus the center of the disk is coincident with the center of the concentrical pregroup and at the same time coincident with the rotational center of the disk when it is driven after assembly. As a result, the defective eccentricity is reduced and furthermore a centering job using a tracking guide is omitted. Then the working efficiency of an optical disk is improved. |
