| 摘要 |
PROBLEM TO BE SOLVED: To improve information recording and reproducing accuracy during the tracking movement of an objective lens. SOLUTION: Because a mirror driving signal DM corresponding to a shift amount of the objective lens 36 and a depth df is calculated according to expressions (6) and (7) with a signal processing part 23 of an optical disk drive 20 based on a push pull tracking error signal STEp including an offset amount caused by a tracking movement of the objective lens 36, a three spot tracking error signal STE3 not including the offset amount, and depth information Idf, a focus Fb of a blue light beam Lb1 is aligned to a target condensing position Pt by adjusting a galvanomirror 54 based on the mirror driving signal DM. COPYRIGHT: (C)2009,JPO&INPIT
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