| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase changeable optical disk capable of executing CAV drive by concentrically dividing a recording area and using phase change materials different in crystallization speed for respective areas. SOLUTION: This optical disk constituted so that the whole recording area 4 is divided concentrically, and phase change material with a relatively small crystallization speed is used as recording material of an inner peripheral part 4a, and the phase change material with a relatively large crystallization speed is used for an outer peripheral part 4b and they are stuck to each other is provided with a half body 1B with the same size as the size of the optical disk 1 provided with a recording part A using the phase change material with the small crystallization speed in its inner peripheral area 1Ba answering to the inner peripheral part 4a, and whose outer peripheral area 1Bb answering to the outer peripheral part 4b is made a transparent state, and the half body 1A with the same size as the size of the optical disk 1 whose inner peripheral area 1Aa answering to the inner peripheral part 4a is made the transparent state, and provided with the recording part B using the phase change material with the large crystallization speed in whose outer peripheral area 1Ab answering to the outer peripheral part 4b, and the disk half bodies 1A, 1B are stuck to each other so that the recording parts A, B are confronted to each other with a central hole 2 as the center. |
