Tracking control method for reading/writing optical disk

1. A tracking control method for use in an optical disk drive to read/write an optical disk, comprising steps of:

measuring a static offset according to an input tracking error signal generated by a detector receiving a single spot reflected from the optical disk;

subtracting the static offset from the input tracking error signal to be a tracking error signal without the static offset;

implementing a tracking servo loop with a frequency compensator-loop;

feeding the tracking error signal without static offset into the tracking servo loop;

using a first memory to learn a periodical offset in the tracking servo loop;

opening the tracking servo loop and driving an actuator by the periodical offset;

using a second memory to learn a dynamical offset according to the periodical offset;

subtracting the static offset and the dynamical offset from the input tracking error signal to be a tracking error signal without the static and dynamical offset; and

closing the tracking servo loop and feeding the tracking error signal without the static and dynamical offset into the closed tracking servo loop.

2. The method according to claim 1 wherein the static offset is obtained by processing the input tracking error signal with a peak detector.

3. The method according to claim 1 wherein the static offset is obtained by processing the input tracking error signal with a low-pass filter.

4. The method according to claim 1 wherein the periodical offset indicates low frequency periodical disturbances inherent in the optical disk.

5. The method according to claim 1 wherein the frequency compensator-loop comprises a filter and a gain element.

6. The method according to claim 1 wherein the dynamical offset is measured as a function of the optical disk's azimuth.