| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk for preventing the illegal copy of a digital work recorded thereon, and to provide a reproduction method, apparatus and recorder of the optical disk. SOLUTION: An optical disk 10 has a control region 12 on which control information is recorded, a data region 14 on which main digital information is recorded, and an identification region 13 on which sub-digital information being peculiar to the main digital information is recorded. In the identification region 13, pit sequences are recorded as sub-digital information with clock timing which is locally phase-modulated. In the case the identification information of the disk if recorded as sub-digital information, key information stored into the recorder and identification information (sub-digital information) detected from the fluctuation of the jitter value in the identification region 13 are compared at the time of playback of the optical disk 10. When a correlation is found between them, it is judged that the disk is authorized and reproduction is permitted, thereby preventing illegal copying. |
