Patent ID: 7145843

Claim:
An optical disk which comprises a track groove and on which positional information indicating a physical location on the track groove is represented by a wobble shape of the track groove, wherein the optical disk includes a plurality of positional information units that are arranged on the track groove, and wherein each said positional information unit includes: a positional information section that represents the positional information by a combination of wobble patterns selected from multiple types of wobble patterns that have been defined so as to correspond to respective signal waveforms that rise and fall mutually differently; a sync mark section having a wobble pattern in a shape distinguishable from the wobble patterns of the positional information section; and a precision positioning mark section ahead of each said positional information section, wherein the positional information is read out from the optical disk by: detecting the sync mark section that has been formed on the optical disk; detecting the precision positioning mark section; establishing a bit synchronization for the positional information using the sync mark section detected and/or the precision positioning mark section detected; and reading out the positional information in accordance with the bit synchronization established in the step of establishing the bit synchronization for the positional information.