| 摘要 |
PROBLEM TO BE SOLVED: To suppress thermal interference and to increase the margin of recording power even when the recording density is increased by having a thermal conductivity layer having a first low-thermal conductivity layer, first high- thermal conductivity layer, second low-thermal conductivity layer and second high-thermal conductivity layer laminated and formed in this order on a recording layer. SOLUTION: A dielectric layer 2, the recording layer 3, the first low-thermal conductivity layer 11, the first high-thermal conductivity layer 12 and a protective layer 5 are successively laminated on a transparent substrate 1. The thermal conductivity control layer 4 is composed of the four layers; the first low-thermal conductivity layer 11, the first high-thermal conductivity layer 12, the second low-thermal conductivity layer 13, and the second high-thermal conductivity layer 14. The thermal conductivity of the first and second high-thermal conductivity layers 12, 14 is selected to be larger than the thermal conductivity of the recording layer 3 and the thermal conductivity of the first and second low- thermal conductivity layers 11, 13 is selected to be smaller than the thermal conductivity of the recording layer 3. The warpage of a disk 20 with an environmental change and more particularly temp. change is thereby decreased. |
