Patent ID: 6014363
Filing Date: 2000-01-11
Classification: G11B

Abstract:
A phase change optical disk medium comprising:a disklike substrate; anda recording layer formed by a laminate of a plurality of thin layers including a phase change layer, tracks for recording information marks being recorded on said phase change layer by phase changes from/to a crystal phase to/from an amorphous phase, and groove portions and land portions being formed on said recording layer so as to take a grooved shape having concave portions that alternate with convex portions,wherein said tracks have an interval in a range of 0.54 to 0.64 .mu.m, and said recording layer has a ratio of optical reflectance equal to or less than 0.35 when said phase change layer has changed to the amorphous phase in case where an optical reflectance of said recording layer is 1 when said phase change layer is in the crystal phase.