| 摘要 |
PURPOSE:To speedily detect a group center at high accuracy by detecting the group center based on the number and width of the pulse signals detected when an optical pickup crosses the group of optical disks. CONSTITUTION:With the group center B of the optical disk 11 deviating from the rotating center A of a rotating table 12, the table 12 is rotated with the center A as a center. The center of a circle D is the rotating center of the table 12. Since it deviates from the group center B of the disk 11, the optical pickup 16 obliquely crosses the group of the disk 11, and at that time a pulse signal is generated from the pickup 16. While a pulse width detection circuit 20 detects the width of the group detection pulse, a motor 13 is rotated, and the table is stopped at a position where the detection pulse width can be maximized. When a stage drive motor 15 linearly moved a stage 14 in a horizontal direction by the deviation quantity obtained through arithmetic, the group center B of the disk 11 moves to the center A position of the rotating table 12.
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