Patent ID: 6108297
Filing Date: 2000-08-22
Classification: G11B

Abstract:
An optical disk, comprising:a plastic substrate having a circular shape; anda recording film on which information is recorded formed on the plastic substrate,wherein the plastic substrate includes a groove formed in a concentric circular shape or spiral shape, the groove having at least a bottom surface, an inner side surface, and an outer side surface, at least one of the side surfaces of the groove having a taper in the direction of the bottom surface, a supplementary angle of the angle created by the inner side surface and the bottom surface being a first angle of inclination, a supplementary angle of the angle created by the outer side surface and the bottom surface being a second angle of inclination, and said first angle of inclination being smaller than said second angle of inclination, and wherein the depth of the groove is in a range of 80 nm-600 nm.