| 摘要 |
PROBLEM TO BE SOLVED: To easily focus on a layer of a moving destination by supplying a kick voltage to an optical pickup when acceleration of a wobbly surface of an optical disk becomes a prescribed value away from the center of the acceleration. SOLUTION: When the optical pickup PU: 4 focalizes on a recording surface of a first layer 2 from a data reproducing state of the recording surface of a second layer 3 of the disk 1, it applies an opposite polarity kick voltage to a focus coil to move the movable part of the PU: 4 toward the first layer 2. A focus error signal outputted from an RF amplifier 5 is supplied to a CPU: 12, and its low-pass component is amplified by an amplifier 13 to be supplied to the CPU: 12. Then, the voltage of the focus error signal is A/D converted by the CPU: 12, and the maximum value and the minimum value of the error signal are obtained, and by calculating its middle timing, a point of time when the acceleration of the wobbly surface of the disk 1 in the vertical direction becomes nearly zero is calculated.
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