| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a deterioration of accuracy of tracking control caused by lens shift. <P>SOLUTION: The optical disc apparatus 20 generates the photo detecting signals SZ1 and SZ2 respectively indicating the light amounts in the divided areas 37Z1 and 37Z2 (Fig. 4) and generates the photo detecting signals SA-SD respectively indicating the light amounts in the divided areas 37A-37D. Subsequently, the optical disc apparatus 20 generates the tracking error signal STE according to the DPD method based on the intermediate values SMA and SMB, each of which is obtained by adding half the photo detecting signal SZ1 to each of the photo detecting signals SA and SB, and the intermediate values SMC and SMD, each of which is obtained by adding half the photo detecting signal SZ2 to each of the photo detecting signals SC and SD and performs the tracking control of the objective lens 28. Therefore, even in the case where the lens shift occurs, the optical disc apparatus 20 may generate a high-quality tracking error signal STE on which the components of the phase changing ranges HA-HD are reflected. <P>COPYRIGHT: (C)2011,JPO&INPIT |
