Method of compensating for microjog error due to repeatable run-out
View Patent ↗A process for continually compensating for the microjog error resulting from RRO. Typically, the 1F RRO is the most significant, but the method could be applied to the microjog error caused by RRO of other frequencies. The process continually determines an instantaneous microjog error based on the RRO and adjusts the read element target position throughout one revolution, such that the write element remains centered on its intended position.
1. A disk drive comprising:
a read/write head having a read element and a write element, wherein the read element and the write element are separated by a preset distance thereby resulting in a microjog distance between the read and write elements as the read/write head is positioned at tracks of the disk;
a control circuit which positions the read/write head along a desired track of the disk, wherein the control circuit adjusts the position of the read/write head based on a repeatable runout measurement of the disk, and the control circuit further adjusts the position of the read/write head based on variations in the microjog distance resulting from adjustments based on the repeatable runout.
2. The disk drive according to claim 1 , wherein the control circuit determines the repeatable runout measurement.
3. The disk drive according to claim 1 , wherein the position adjustment of the read/write head centers the write element on a write target position.
4. The disk drive according to claim 1 , wherein the control circuit positions the read element based on the repeatable runout measurement.
5. The disk drive according to claim 1 , wherein the error due to the repeatable runout measurement is determined by the equation:
sin(w)*(calc_calibrated_microjog(head,track+RRO)−calc_calibrated_microjog(head,track));
where w refers to the angle through which the disk rotates, synchronized with the phase of the repeatable runout.
6. The disk drive according to claim 1 , further comprising a removable cartridge, wherein the cartridge contains a storage medium.
7. The disk drive according to claim 6 , wherein the storage medium is a magnetic media.
8. The disk drive according to claim 6 , wherein the control circuit disables write functionality when the repeatable runout measurement exceeds a predetermined threshold.
9. A method of compensating for microjog error due to repeatable runout comprising:
determining a nominal microjog distance based on a location of a read/write head relative to a disk;
obtaining a repeatable runout measurement of the disk;
calculating an instantaneous microjog error due to the repeatable runout; and
adjusting the nominal microjog distance in accordance with the instantaneous microjog error.
10. The method according to claim 9 , further comprising applying the instantaneous microjog error to position a write element.
11. The method according to claim 10 , further comprising centering the write element on a write target position.
12. The method according to claim 9 , further comprising calculating the instantaneous microjog error using the formula:
sin(w)*(calc_calibrated_microjog(head,track+RRO)−calc_calibrated_microjog(head,track))
where w refers to the angle through which the disk rotates, synchronized with the phase of the repeatable runout.
13. The method according to claim 9 , further comprising obtaining a new repeatable runout measurement upon insertion of a removable cartridge.
14. The method according to claim 13 , wherein the removable cartridge contains storage media.
15. The method according to claim 9 , further comprising disabling write functionality when the repeatable runout measurement exceeds a predetermined threshold.
16. A method of positioning a read/write head in a disk drive, the method comprising:
positioning a read/write head along a desired track of the disk, the read/write head having a read element and a write element, wherein the read element and the write element are separated by a preset distance thereby resulting in a microjog distance between the read and write elements as the read/write head is position at tracks of the disk;
varying the position of the read/write head based on a repeatable runout measurement of the disk; and
adjusting the position of the read/write head based on variations in the microjog distance resulting from varying the position of the read/write head based on the repeatable runout.
17. A disk drive comprising:
a read/write head having a read element and a write element, wherein the read element and the write element are separated by a preset distance;
a control circuit which positions the read element centered on a read target position while writing data with the write element to a write track, then when reading the data written to the write tack, the controller positions the read element to a nominal write track position and further adjusts the position of the read element about the nominal write track position based on microjog variations resulting from adjustments based on instantaneous repeatable runout measurements.
18. The disk drive according to claim 17 , further comprising a removable cartridge, wherein the cartridge contains a storage medium.
19. The disk drive according to claim 17 , further comprising a fixed storage medium.