Disk drive compensation of bias imparted by a flex circuit cable utilizing a dual bias curve estimation scheme
View Patent ↗A disk drive comprising an actuator including a head, a disk, and a processor connected to the actuator by a flex circuit cable. The processor under the control of a program to: apply a control signal for a seek operation and to apply a bias signal to the control signal to approximate the bias imparted by the flex circuit cable. The bias is determined from a data structure that stores: bias values for track zones representative of a first and second bias curves that approximate a bias imparted by the flex circuit cable upon the actuator as the actuator moves the head from the OD to the ID of the disk and from the ID to the OD of the disk, respectively. The bias values representative of the first and second bias curves are determined based upon a non-linear apportionment of track zones.
1. A disk drive comprising:
an actuator including a head;
a disk having an outer diameter (OD) and an inner diameter (ID) and a plurality of tracks therebetween, the disk being divided into a plurality of track zones each having a plurality of tracks; and
a processor for controlling operations in the disk drive including a seek operation from a first track to a second track in which the head is moved between the first track and the second track by movement of the actuator, the processor being connected to the actuator by a flex circuit cable, the processor under the control of a program to:
apply a control signal for the seek operation to command the actuator to move the head from the first track to the second track;
apply a bias signal to the control signal to approximate the bias imparted by the flex circuit cable, the bias being determined from a data structure, the data structure storing:
bias values for each of the track zones representative of a first bias curve to approximate a bias imparted by the flex circuit cable upon the actuator as the actuator moves the head from the OD to the ID; and
bias values for each of the track zones representative of a second bias curve to approximate a bias imparted by the flex circuit cable upon the actuator as the actuator moves the head from the ID to the OD;
wherein the bias values representative of the first and second bias curves are determined based upon a non-linear apportionment of track zones.
2. The disk drive of claim 1 , wherein the non-linear apportionment of track zones includes a substantially greater number of track zones being apportioned towards the OD of the disk.
3. The disk drive of claim 1 , wherein the non-linear apportionment of track zones includes a substantially greater number of track zones being apportioned towards the ID of the disk.
4. The disk drive of claim 1 , wherein the non-linear apportionment of track zones includes a substantially greater number of track zones being apportioned towards the ID of the disk and the OD of the disk and a lesser number of track zones being apportioned to a middle diameter section of the disk.
5. The disk drive of claim 1 , wherein the bias values representative of the first and second bias curves are initially determined during the calibration of the disk drive.
6. The disk drive of claim 5 , wherein the bias values representative of the first and second bias curves are determined during the calibration of the disk drive and are stored in the data structure on the disk of the disk drive.
7. The disk drive of claim 5 , wherein during power-up of the disk drive, offset values from the determined bias values representative of the first and second bias curves are calculated.
8. The disk drive of claim 7 , wherein the offset values are stored in memory and are adapted during seeking.
9. The disk drive of claim 1 , wherein the data structure is a look-up table.
10. In a disk drive including a disk having an outer diameter (OD) and an inner diameter (ID) and a plurality of tracks therebetween in which the disk is divided into a plurality of track zones, the disk drive including an actuator having a head, the actuator being connected to processing circuitry of the disk drive by a flex circuit cable, a method to implement a seek operation to move the head from a first track to a second track that includes compensating for the bias imparted by the flex circuit cable comprising:
applying a control signal for the seek operation to command the actuator to move the head from the first track to the second track; and
applying a bias signal to the control signal to approximate the bias imparted by the flex circuit cable, the bias being determined from a data structure, the data structure storing:
bias values for each of the track zones representative of a first bias curve to approximate a bias imparted by the flex circuit cable upon the actuator as the actuator moves the head from the OD to the ID; and
bias values for each of the track zones representative of a second bias curve to approximate a bias imparted by the flex circuit cable upon the actuator as the actuator moves the head from the ID to the OD;
wherein the bias values representative of the first and second bias curves are determined based upon a non-linear apportionment of track zones.
11. The method of claim 10 , wherein the non-linear apportionment of track zones includes a substantially greater number of track zones being apportioned towards the OD of the disk.
12. The method of claim 10 , wherein the non-linear apportionment of track zones includes a substantially greater number of track zones being apportioned towards the ID of the disk.
13. The method of claim 10 , wherein the non-linear apportionment of track zones includes a substantially greater number of track zones being apportioned towards the ID of the disk and the OD of the disk and a lesser number of track zones being apportioned to a middle diameter section of the disk.
14. The method of claim 10 , wherein the bias values representative of the first and second bias curves are initially determined during calibration of the disk drive.
15. The method of claim 14 , wherein the bias values representative of the first and second bias curves determined during calibration of the disk drive are stored in the data structure on the disk of the disk drive.
16. The method of claim 14 , wherein during power-up of the disk drive, offset values from the initially determined bias values representative of the first and second bias curves are calculated.
17. The method of claim 16 , wherein the offset values are stored in memory and are adapted during seeking.
18. The method of claim 10 , wherein the data structure is a look-up table.