Optical recording medium driving device, focus on how

摘要

PROBLEM TO BE SOLVED: To speed up focusing when using an L0 layer of a two-layered BD as a target layer, for example.;SOLUTION: When using the L0 layer as the target layer, the focusing is carried out by setting up the spherical aberration correction obtained by adding the compensation shift b calculated to maximize the RF signal amplitude, for example, to the spherical aberration correction for the center point between the L1 layer and the L0 layer. Thus, the distortions of the focusing error signals are improved for the L1 layer and the L0 layer even when there are cover thickness differences between disks, and the focusing is achieved by driving the objective lens in one direction since the S curve of the L1 layer is appropriately found.;COPYRIGHT: (C)2008,JPO&INPIT