| 摘要 |
PROBLEM TO BE SOLVED: To stably perform the re-adjustment of a focal distance also in an optical disk having large plane wobbling. SOLUTION: This data reading device is provided with a position variation detecting means detecting a position of an optical pickup based on an adjustment quantity of a focal distance when an optical pickup irradiates a recording medium with a laser beam, a position variation recording means recording a variation of a position of the optical pickup detected by the position variation detecting means, and a focal distance re-adjusting means performing the re-adjustment of the focal distance by setting an approach limit distance between the recording medium and the optical pickup by subtracting a variation quantity of a position of an optical pickup recorded in the position variation recording means. COPYRIGHT: (C)2009,JPO&INPIT
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