Optical disk of sampled servo type having synchronization a marks for simple synchronization detection

摘要

An optical disk with tracks having a sampled servo type recording format, and comprising a preformatted servo field including a synchronous mark for synchronization detection and a data field for recording data on each track. In the optical disk, the synchronous marks are aligned in the same radial direction of the disk per track and have the edge interval longer than the maximum inversion interval of the mark for the data in the track direction, and the interval of the synchronous mark between the adjacent tracks is made smaller than the spot diameter of a reading beam. Hence, in the radial direction of the disk where the synchronous marks are present, the synchronous mark is included in the spot of the reading beam of a pickup irrespective of being on-track or off-track to make it possible to obtain substantially the same level for synchronous signals.