| 摘要 |
PURPOSE:To prevent the center hole, the track, the outside diameter of an optical disc from being eccentric, by providing a ring-shaped information forming layer on one face of a substrate with the rotation center hole as the center and providing a substrate center positioning mark in the part other than the information forming layer. CONSTITUTION:Al or the like is vapor-deposited to form an information forming layer 5 in a surface rugged part 4 as an information signal or tracking guide, which is formed to a shape like a ring with a rotation center hole 2 as the center, on one face of a substrate 3, thus obtaining an information storage medium 1 (optical disc). In case that the rotation center hole 2 of this optical disc 1 is drilled, a substrate center positioning mark 6 is provided in a part other than the region of the information forming layer 5 for the purpose of preventing eccentricity. A protection sheet is covered on the information forming layer 5 of the substrate 3, and the rotation center hole 2 is worked on a basis of the substrate center positioning mark 6. Thus, the center hole 2 of the optical disc 1, the surface rugged part 4 of the track, and the outside diameter of the substrate 3 are prevented from being eccentric. |
