| 摘要 |
PURPOSE:To obtain such a medium that can inform users that recording/ reproducing is impossible due to deterioration of a recording layer by providing a monitor layer in an area where recording on the recording layer can not be affected, and by incorporating dyes which easily fade compared to dyes contained in the recording layer into the monitor layer. CONSTITUTION:The optical disk consists of a disk substrate 3 having a center hole 2, a recording layer 4 provided on the one side 3A of the substrate 3, and a reflecting layer on the recording layer, and a protective layer 6 on the reflecting layer. On the side 3B which is opposite to the recording layer, and indication area 7 is provided on the outer circumferential edge 3a, and further a monitor layer 8 is provided on the indication area 7. The indication area 7 consists of such a material which hardly deteriorate under any environmental condition, and it indicates or warns a deteriorated state of the recording layer 4. By this constitution, disability in data recording/reproducing due to deterioration of the recording layer can be priorly warned users. |
