| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk drive in which a tracking error signal can be switched to a DPD (Differential Phase Detection) system or a PP (Push Pull) system in accordance with change in a region to be tracked. SOLUTION: When a HD (High Definition) DVD 100 which is provided with an area 101 for reproduction only in which information is formed by pits, a recordable area 2 in which information is recorded in land/groove, and a flat signal-less area 103 existing between the area for reproduction only and the recordable area is played back, tracking is performed by the DPD system in the area 101 for reproduction only, and tracking is performed by the PP system in the recordable area 102. The tracking system is switched by detecting a signal by a laser beam reflected by the signal-less area 103 included in a RF signal and thereby detecting change from the area 101 for reproduction only of the tracking area to the recordable area 102 or change from the recordable area 102 to the area 101 for reproduction only. Thus, the tracking of the HD DVD 100 can be smoothly performed. COPYRIGHT: (C)2005,JPO&NCIPI
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