Granted Patent B1

US 9,245,560 · App. 14/642,684 · Granted Jan 26, 2016

Abstract

Claims (42)

1. A data storage device comprising:

a disk comprising a spiral track;

a head actuated over the disk, the head comprising a read element offset radially from a write element by a reader/writer offset; and

control circuitry configured to:

first read the spiral track to write a plurality of concentric servo sectors on the disk that define at least one concentric servo track on the disk;

generate a first radial location measurement based on reading the spiral track;

generate a second radial location measurement based on reading the concentric servo sectors; and

measure the reader/writer offset based on a difference between the first and second radial location measurements.

2. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to:

read the spiral track to write the plurality of concentric servo sectors on the disk to define a plurality of concentric servo tracks on the disk; and

read the spiral track and the concentric servo sectors at a plurality of different radial locations to generate the reader/writer offset measurement at each radial location.

3. The data storage device as recited in claim 2 , wherein the control circuitry is further configured to:

curve fit the reader/writer offset measurements to a polynomial; and

generate a reader/writer offset error at each of the different radial locations based on a difference between the measured reader/writer offset and a nominal reader/writer offset generated based on the polynomial.

4. The data storage device as recited in claim 3 , wherein the control circuitry is further configured to read the spiral track and use the reader/writer offset error to rewrite at least one of the concentric servo tracks at a different radial location in order to compensate for the reader/writer offset error.

5. A data storage device comprising:

a disk comprising a spiral track;

a head actuated over the disk, the head comprising a read element offset radially from a write element by a reader/writer offset; and

control circuitry configured to:

first read the spiral track to write a plurality of concentric servo sectors on the disk that define at least one concentric servo track on the disk at a first radial location;

measure the reader/writer offset; and

second read the spiral track and use the measured reader/writer offset to rewrite at least one of the concentric servo tracks at a second radial location different from the first radial location.

6. The data storage device as recited in claim 5 , wherein rewriting the concentric servo track compensates for an error in the measured reader/writer offset.

7. The data storage device as recited in claim 6 , wherein the control circuitry is further configured to third read the spiral track and the concentric servo sectors to measure the reader/writer offset.

8. A method of operating a data storage device, the method comprising:

using a head to first read a spiral track on a disk to write a plurality of concentric servo sectors on the disk that define at least one concentric servo track on the disk;

generating a first radial location measurement based on reading the spiral track;

generating a second radial location measurement based on reading the concentric servo sectors; and

measuring a reader/writer offset between a read element of the head and a write element of the head based on a difference between the first and second radial location measurements.

9. The method as recited in claim 8 , further comprising:

reading the spiral track to write the plurality of concentric servo sectors on the disk to define a plurality of concentric servo tracks on the disk; and

reading the spiral track and the concentric servo sectors at a plurality of different radial locations to generate the reader/writer offset measurement at each radial location.

10. The method as recited in claim 9 , further comprising:

curve fitting the reader/writer offset measurements to a polynomial; and

generating a reader/writer offset error at each of the different radial locations based on a difference between the measured reader/writer offset and a nominal reader/writer offset generated based on the polynomial.

11. The method as recited in claim 10 , further comprising reading the spiral track and using the reader/writer offset error to rewrite at least one of the concentric servo tracks at a different radial location in order to compensate for the reader/writer offset error.

12. A method of operating a data storage device, the method comprising:

using a head to first read a spiral track on a disk to write a plurality of concentric servo sectors on the disk that define at least one concentric servo track on the disk at a first radial location;

measuring a reader/writer offset between a read element of the head and a write element of the head; and

using the head to second read the spiral track and using the measured reader/writer offset to rewrite at least one of the concentric servo tracks at a second radial location different from the first radial location.

13. The method as recited in claim 12 , wherein rewriting the concentric servo track compensates for an error in the measured reader/writer offset.

14. The method as recited in claim 13 , further comprising third reading the spiral track and the concentric servo sectors to measure the reader/writer offset.

Assignments (8)