| 摘要 |
PURPOSE:To always understand the light beam deflection degree on the target track and to ensure the optimum positioning, by storing the eccentricity degree of a disk and applying the servo control to the track at the center of eccentricity. CONSTITUTION:A differential signal (d) of a track error signal obtained when a light beam passes through a track is detected 8 with separation 7 into inner and outer circumference directions for the shift of the light beam when no tracking servo control is applied. Then the differential signals are counted by a counter 10 for each track pulse train of one side to obtain an eccentricity degree of a disk. This eccentricity degree is stored in a register 11. Then the value of the counter 10 is compared 12 with the value of the register 11, and the tracking servo control is started when the value of the counter 10 is equal to 1/2 eccentricity degree of the disk. |
