Self-servo writing using staged patterning
View Patent ↗An apparatus and method for servo writing are disclosed. The method includes writing of first servo data to a medium, detecting a velocity integrated position of the first servo data, and writing second servo data in relation to the detected position of the first servo data.
1. A method comprising self-servo writing servo data to a storage medium by using a first open loop seek to write a spiral of coarse servo data to the medium, and using a second open loop seek to detect a position error of said spiral.
2. The method of claim 1 , wherein the detected position error is characterized in relation to a detected position of an outermost radial location and an innermost radial location of the spiral, and in relation to an integrated velocity of a transducer moved during the second open loop seek as the transducer crosses the spiral.
3. The method of claim 1 , wherein the spiral of coarse servo data comprises a contiguous spiral that extends between an outermost diameter (OD) and an innermost diameter (ID) of the medium written as a transducer is continuously moved between said OD and said ID during the first open loop seek.
4. The method of claim 1 , further comprising using a third open loop seek to write a second spiral of coarse servo data to the medium in relation to the detected position error, and using position information from the second spiral of coarse servo data to write a plurality of spaced apart servo wedges that radially extend across the medium from said OD to said ID.
5. The method of claim 1 , wherein the second open loop seek is carried out by moving a transducer in accordance with a predetermined detection seek profile, and wherein the position error is detected in relation to an integrated velocity value of the transducer obtained as the transducer crosses the spiral.
6. The method of claim 1 , wherein the first open loop seek is carried out by constantly moving a transducer at a first commanded non-zero velocity across the medium while writing said spiral, and wherein the second open loop seek is carried out by constantly moving the transducer at a different, second commanded non-zero velocity across the medium so as to pass over the spiral.
7. The method of claim 6 , wherein a duration of the first open loop seek and a magnitude of the first commanded non-zero velocity are selected to move the transducer from a selected one of an innermost diameter (ID) or outermost (OD) of the medium to a remaining one of the ID or OD.
8. The method of claim 6 , wherein a duration of the second open loop seek and a magnitude of the second commanded non-zero velocity are selected to move the transducer from a selected one of an innermost diameter (ID) or outermost (OD) of the medium to a remaining one of the ID or OD.
9. The method of claim 1 , further comprising storing the detected position error in a memory structure.
10. An apparatus comprising a controller of a data storage device configured to direct a transducer of the device to self-servo write servo data to a storage medium by using a first open loop seek to write a spiral of coarse servo data to the medium, and using a second open loop seek to detect a position error of said spiral.
11. The apparatus of claim 10 , wherein the position error is further characterized in relation to detected position of an outermost radial location and an innermost radial location of the spiral.
12. The apparatus of claim 10 , wherein the controller further directs the transducer to carry out a third open loop seek to write a second spiral of coarse servo data to the medium in relation to the position error detected during the second open loop seek.
13. The apparatus of claim 10 , wherein the second open loop seek is carried out by moving the transducer at a selected velocity, and wherein the position error is detected by integrating said velocity as the transducer crosses the spiral.
14. The apparatus of claim 10 , wherein the first open loop seek is carried out by constantly moving the transducer at a first commanded non-zero velocity across the medium while writing said spiral, and wherein the second open loop seek is carried out by constantly moving the transducer at a different, second commanded non-zero velocity across the medium so as to intersect the spiral.
15. The apparatus of claim 10 , wherein a duration of the first open loop seek is selected to move the transducer from a selected one of an innermost diameter (ID) or outermost (OD) of the medium to a remaining one of the ID or OD.
16. The apparatus of claim 10 , wherein a duration of the second open loop seek is selected to move the transducer from a selected one of an innermost diameter (ID) or outermost (OD) of the medium to a remaining one of the ID or OD.
17. An apparatus comprising:
a moveable transducer adjacent a storage medium; and
first means for using a succession of open loop seeks of the transducer to self-servo write servo data to the storage medium;
wherein the first means is characterized as a servo controller of a data storage device in which the transducer and the medium are disposed, wherein the servo controller directs the transducer to carry out a first open loop seek to write a spiral of coarse servo data to the medium, and to carry out a second open loop seek to detect a position error of said spiral.
18. The apparatus of claim 17 , wherein the servo controller further directs the transducer to carry out a third open loop seek to write a second spiral of coarse servo data to the medium in relation to the detected position error.
19. The apparatus of claim 17 , wherein the servo controller further directs the transducer to write a plurality of spaced apart servo wedges that radially extend across the medium from said OD to said ID in relation to position information from the second spiral.