| 摘要 |
PURPOSE:To reduce the probability of the occurrence of a read error by preventing the adverse effect of a preformat at the time of reading data from an optical disk provided with projecting/recessing parts for the preformat on the disk plate surface of the lower side of the recording medium of a phase change. type. CONSTITUTION:The depth (d) of the projecting/recessing parts 14 of the preformat part PF on a track 12 and the area ratio of the recessing parts and the projecting parts is deviated slightly from a value that the interference of the reflected beam of a laser beam for reading from the projecting/recessing parts becomes a maximum. Thus, the amplitudes of waveform changes in the preformat part PF of a detective signal DS by a head and a storage data part MD are nearly uniformed, and the occurrence of the error is prevented by eliminating timing deviation from the write pitch (p) of a data code to the storage data part MD of the waveform of a read signal RSa after the amplitudes are converted by an AGC circuit. |
