| 摘要 |
PURPOSE:To prevent the unsuccessful relief of a kickback and an excessive off-track by providing a track guide groove in the rotating direction opposite to the rotating direction of a spiral-like track guide groove, and a track guide groove in the same rotating direction, on the outside of the outermost circumference of an additional type optical disk, and the inside of the innermost circumference, respectively. CONSTITUTION:A format decoder 10 detects and discriminates by information from a device part 9 whether an additional track guide groove which has caught an optical disk device 8 is an outside circumferential side additional track guide groove 3 or an inside circumferential side additional track guide groove 4. Subsequently, information is outputted to a microprocessor 6. If a failure of a kickback or an excessive off-track occurs in the outside circumferential side of a track guide groove 1, an optical disk device which has moved through a locus shown by a broken line is caught by the outside circumferential side additional track guide groove 3 and can be returned to a normal locus. |
