A disc drive detects and uses the information included in a header of a sector positioned near a track change between a land track and a groove track.

• A land track and a groove track are switched successively and alternately every spiral track.
• A sector among plural sectors arranged along the spiral track, which positions directly before a track change, includes a header having information indicating such track change.
• A Optical disc device detects the information of a track change and thereby controls a tracking.

[References]

• DVD Specifications for Rewritable Disc: Part 1 Version 1.0, 2.0, Index 5.2.4

[Offering Patent]

• USP6,172,961
• Others (JP, GB, FR, KR, TW, CN)