Disk device conducting a disturbance compensation based on a time-interval measurement in reading servo sectors recorded on a disk

1. A disk device comprising:

a disk having predetermined information sectors recorded at a constant interval;

a head scanning said disk; and

a disturbance-compensation unit obtaining an amount of a disturbance based on a time-interval measurement in reading said predetermined information sectors so as to compensate a position of said head according to the amount of the disturbance.

2. The disk device as claimed in claim 1 , wherein said disturbance-compensation unit compensates a tracking error signal according to the amount of the disturbance, the tracking error signal corresponding to a positional error of said head on said disk.

3. The disk device as claimed in claim 1 , wherein said disturbance-compensation unit includes:

an angular-acceleration calculating unit calculating a rotational angular acceleration of a motor based on the time-interval measurement, the motor rotating said disk; and

a disturbance-compensation amount calculating unit calculating a disturbance-compensation amount based on said rotational angular acceleration so as to compensate the position of said head according to said disturbance-compensation amount.

4. The disk device as claimed in claim 3 , wherein said disturbance-compensation unit further includes a filter filtering a value of said rotational angular acceleration including a vibration of the disturbance so as to supply said value to said disturbance-compensation amount calculating unit.

5. The disk device as claimed in claim 1 , wherein said disturbance-compensation unit includes:

an angular-velocity calculating unit calculating a rotational angular velocity of a motor based on the time-interval measurement, the motor rotating said disk;

an angular-acceleration calculating unit calculating a rotational angular acceleration of said motor based on said rotational angular velocity; and

a disturbance-compensation amount calculating unit calculating a disturbance-compensation amount based on said rotational angular acceleration so as to compensate the position of said head according to said disturbance-compensation amount.

6. The disk device as claimed in claim 5 , wherein said disturbance-compensation unit further includes a filter filtering a value of said rotational angular velocity including a vibration of the disturbance so as to supply said value to said angular-acceleration calculating unit.

7. The disk device as claimed in claim 5 , wherein said angular-acceleration calculating unit is composed of a differential filter.

8. The disk device as claimed in claim 1 , wherein said disturbance-compensation unit includes a repeatable run-out amount obtaining unit obtaining a repeatable run-out amount of said head in relation to said disk so as to adjust the amount of the disturbance by the repeatable run-out amount.

9. The disk device as claimed in claim 8 , wherein said repeatable run-out amount obtaining unit obtains said repeatable run-out amount by preliminarily detecting a deviation amount of said head affected by few disturbances, said head deviating from a track of said disk by the deviation amount.

10. The disk device as claimed in claim 8 , wherein said repeatable run-out amount obtaining unit calculates an average of repeatable run-out amounts of said head measured at a plurality of points on said disk so as to adjust the amount of the disturbance by said average.

11. The disk device as claimed in claim 8 , wherein said repeatable run-out amount obtaining unit divides said disk into a plurality of zones so as to obtain the repeatable run-out amount in each of said zones.

12. A disturbance compensation method for a disk device including a disk having predetermined information sectors recorded at a constant interval, and a head scanning said disk, the method comprising the steps of:

obtaining an amount of a disturbance based on a time-interval measurement in reading said predetermined information sectors; and

compensating a position of said head according to the amount of the disturbance.

13. The disturbance compensation method as claimed in claim 12 , further comprising the step of compensating a tracking error signal according to the amount of the disturbance, the tracking error signal corresponding to a positional error of said head on said disk.

14. The disturbance compensation method as claimed in claim 12 , further comprising the steps of:

calculating a rotational angular acceleration of a motor based on the time-interval measurement, the motor rotating said disk; and

calculating a disturbance-compensation amount based on said rotational angular acceleration so as to compensate the position of said head according to said disturbance-compensation amount.

15. The disturbance compensation method as claimed in claim 12 , further comprising the steps of:

calculating a rotational angular velocity of a motor based on the time-interval measurement, the motor rotating said disk;

calculating a rotational angular acceleration of said motor based on said rotational angular velocity; and

calculating a disturbance-compensation amount based on said rotational angular acceleration so as to compensate the position of said head according to said disturbance-compensation amount.

16. The disturbance compensation method as claimed in claim 12 , further comprising the steps of:

obtaining a repeatable run-out amount of said head in relation to said disk; and

adjusting the amount of the disturbance by the repeatable run-out amount.

17. The disturbance compensation method as claimed in claim 16 , further comprising the step of preliminarily detecting a deviation amount of said head affected by few disturbances, said head deviating from a track of said disk by the deviation amount, so as to obtain said repeatable run-out amount.

18. The disturbance compensation method as claimed in claim 16 , further comprising the step of calculating an average of repeatable run-out amounts of said head measured at a plurality of points on said disk so as to adjust the amount of the disturbance by said average.

19. The disturbance compensation method as claimed in claim 16 , further comprising the step of dividing said disk into a plurality of zones so as to obtain the repeatable run-out amount in each of said zones.

20. A disk device operable with a disk that is prerecorded with predetermined information at constant intervals, comprising:

a head configured to read information from the disk; and

a compensation unit configured to obtain an amount of disturbance based on time intervals of the predetermined information read by said head, and to compensate a position of said head based on the obtained amount of disturbance.