| 摘要 |
PURPOSE:To improve the alignment accuracy by using an optical head for multi-beam, obtaining the servo signal of each track and averaging the servo signal. CONSTITUTION:A multi-beam optical head 1 is used, the servo signal is detected from a track other than the track recording and reproducing the data signal to extract a position error from each track of multi-beam. Then the sum of error signals is calculated and the value dividing the sum by the number of beams is used as the servo error signal, the signal is used to align the optical head. That is, if the number of beams of the optical head 1, is e.g., 5, an abnormal servo signal due to the flaw of a medium 20 is corrected by the servo signals reproduced by other four beams. Then the accuracy of positioning of the optical head 1 of flaw part in the medium 20 can be improved. |
