Patent ID: 7136335

Claim:
An information recording medium for recording main information and auxiliary information, wherein: the information recording medium comprises a track; the main information is recorded on the information recording medium in a manner that pits or recording marks indicating the main information are provided on the information recording medium in a track direction; the auxiliary information is recorded on the information recording medium in a manner that edge positions of the pits or the recording marks are shifted either in a phase advancing direction or in a phase delaying direction along the track direction; a predetermined frequency is used to determine whether the edge position is shifted in the phase advancing direction or in the phase delaying direction in order to record the auxiliary information; the predetermined frequency is substantially consistently lower than ½ of a reference frequency of a recording clock for creating the pits or the recording marks and is higher than a response frequency of a PLL for generating a reproduction clock for reproducing the main information; the predetermined frequency is determined based on a result of a first logic operation of a predetermined binary sequence and the auxiliary information; and the frequency of the predetermined binary sequence is lower than ½ of the reference frequency of the recording clock and is higher than the response frequency of the PLL.