| 摘要 |
<P>PROBLEM TO BE SOLVED: To shorten processing time and secure processing precision when a plurality of recording layers are subjected to a focus offset processing in an optical disk device. Ž<P>SOLUTION: A focus offset for recording or reproducing is set by learning the focus offset of the optical system with respect to a guide groove on the basis of a signal by light reflected on the guide groove formed on the recording face of the recording layer for each of recording layers adjacent to each other, and calculating it on the basis of the learned focus offset of each of the recording layers. As for the focus offset of the optical system for recording or reproducing, the average value of the learned focus offsets of each of the recording layers is set as the focus offset common to both recording layers, or a focus offset is set, of which the difference from the learned focus offset of each of the recording layers becomes a value corresponding to the characteristics of the optical system. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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