Method for determining a compensation value for tracking error signal

1. A method for determining a compensation value for tracking error signal, applied in an optical disc drive, the optical disc drive rotating a DVD at a speed and reading data on the DVD, the DVD having a first reflection layer and a second reflection layer, the first reflection layer having a plurality of circles of first tracks, the second reflection layer having a plurality of circles of second tracks, the method comprising:

respectively reading data on two first tracks and two second tracks when the optical disc drive rotates the DVD at the speed, and accordingly generating two first compensation values for tracking error signal and two second compensation values for tracking error signal, wherein two of the first tracks are an innermost track and a middle track located between the innermost track and an outermost track;

determining a third compensation value for tracking error signal corresponding to each of the other first tracks when the optical disc drive rotates the DVD at the speed according to two of the first compensation values for tracking error signal and position of each of the other first tracks relative to two of the first tracks, wherein the third compensation value corresponding to the first tracks between the innermost track and the middle track is calculated by using a first numerical method and the third compensation value corresponding to the first tracks between the outermost track and the middle track is calculated by using a second numerical method; and

determining a forth compensation value for tracking error signal corresponding to each of the other second tracks when the optical disc drive rotates the DVD at the speed according to two of the second compensation values for tracking error signal and position of each of the other second tracks relative to two of the second tracks.

2. The method according claim 1 , wherein the first numerical method is a linear interpolation method.

3. The method according to claim 1 , wherein the first numerical method is a quadratic interpolation method.

4. The method according to claim 1 , wherein the second numerical method is a linear extrapolation method.

5. The method according to claim 1 , wherein the second numerical method is a quadratic extrapolation method.

6. The method according to claim 1 , wherein two of the second tracks are an innermost track and an outermost track, the step of determining the forth compensation values for tracking error signal comprises:

calculating the forth compensation value for tracking error signal corresponding to each of the second tracks other than the innermost track and the outermost track by using a numerical method.

7. The method according to claim 6 , wherein the numerical method is a linear interpolation method.

8. The method according to claim 6 , wherein the numerical method is a quadratic interpolation method.

9. The method according to claim 1 , wherein two of the second tracks are an innermost track and a middle track located between the innermost track and an outermost track, the step of determining the forth compensation value for tracking error signal comprises:

calculating the forth compensation value for tracking error signal corresponding to each of the second tracks between the innermost track and the middle track by using a first numerical method; and

calculating the forth compensation values for tracking error signal corresponding to the outermost track and the second tracks between the outermost track and the middle track by using a second numerical method.

10. The method according claim 9 , wherein the first numerical method is a linear interpolation method.

11. The method according claim 9 , wherein the first numerical method is a quadratic interpolation method.

12. The method according claim 9 , wherein the second numerical method is a linear extrapolation method.

13. The method according claim 9 , wherein the second numerical method is a quadratic extrapolation method.