| 摘要 |
PURPOSE:To use an optical disk and to improve the yield by providing a track marker on a part which has passed through a defect on the recording surface of a disk, and deciding the moving direction by detecting this track marker. CONSTITUTION:In case when there is a defect 3 on the surface of an optical disk, a marker bit 2 provided with a track marker (ID) is provided on an area which has passed through the defect 3. This area is constituted of 2 parts A, B, both of them take the number of bits extending over the maximum length or the maximum width of the defect 3, from the defect end of each track, and that which has constituted a track code of the number of bits is provided respectively. According to such a constitution, a track marker bit which has passed through the defective part is detected by an ID detecting circuit, and recovery to its original track is executed in the area of the marker bit. In this way, even if there is a small defect extending over plural tracks, an optical disk can be used, and its yield is elevated. |
