| 摘要 |
PURPOSE:To simultaneously obtain the data of an eccentricity amount by forming a pit length which is changed in every track from the inner to the outer peripheries or from the outer to the inner peripheries of the disk in the PEP(phase encoded part) control data area of a preformatting part. CONSTITUTION:A PEP control data area 3a in one track is formed so that the pit length P of a pit 9 gradually becomes longer as the pit goes from the inner periphery to the outer periphery of a disk, about 600-700 tracks exist in the area 3a and the pit duty ratio increases in every track. A recording/ reproducing optical head (not shown in the figure) scans the positions A, B, C, the reproducing signal changes as (a)-(c), by revolving an optical disk 1, since the position of the recording/reproducing optical head is moved from the inner periphery to the outer periphery with the period of one revolution due to eccentricity, the eccentricity amount of the optical disk 1 is obtained by measuring the change of the pulse width T of the reproducing signal. |
