Adjacent track interference asymmetry mitigation

• US 9,672,845 B2
• Filed: 08/24/2015
• Issued: 06/06/2017
• Est. Priority Date: 11/24/2014
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Rausch, Tim
• Primary Examiner(s): Wong, K.
• Application Number:
  US14/833,342
• Publication Number:
  US 20160148630A1
• Time in Patent Office: 652 Days
• Field of Search: None
• CPC Class Codes: G11B 11/10506 by modulating only the light beam of the transducer
• CPC Class Codes: G11B 11/10515 Reproducing compensating pit shift G11B11/1053
• CPC Class Codes: G11B 11/10521 using a single light spot
• CPC Class Codes: G11B 11/10595 Control of operating function
• CPC Class Codes: G11B 20/12 Formatting, e.g. arrangement of data block or words on the record carriers within interface between computers and data recorders G06F3/06
• CPC Class Codes: G11B 20/1217 on discs
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence
• CPC Class Codes: G11B 20/1889 with discs
• CPC Class Codes: G11B 2005/0021 Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal
• CPC Class Codes: G11B 2020/1222 ECC block, i.e. a block of error correction encoded symbols which includes all parity data needed for decoding pure error correction aspects G11B20/18
• CPC Class Codes: G11B 2020/1232 sector, i.e. the minimal addressable physical data unit
• CPC Class Codes: G11B 2020/1238 track, i.e. the entire a spirally or concentrically arranged path on which the recording marks are located
• CPC Class Codes: G11B 2020/1292 Enhancement of the total storage capacity
• CPC Class Codes: G11B 27/3027 used signal is digitally coded
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/09 Digital recording
• CPC Class Codes: G11B 5/59633 Servo formatting G11B5/59627, G11B5/59677, G11B5/59683, G11B5/59688 take precedence
• CPC Class Codes: G11B 5/59638 Servo formatting apparatuses, e.g. servo-writers
• CPC Class Codes: G11B 5/6088 Optical waveguide in or on flying head

Abstract

A storage device includes a controller that selects an offset when preparing to write data to a target data track. The offset defines a position for a write head relative to a center of the target track and is selected based on a radial position of a write head at the target data track.

Claims

1. An apparatus, comprising:

a storage device controller configured to position a write head at an offset from a center of a target data track and write data to the target data track with the write head positioned at the offset, the offset selected based on a radial position of a write head at the target data track.

2. The apparatus of claim 1, wherein the offset is in a direction toward an inner diameter of a storage medium when the write head is at a first radial position and the offset is in an opposite direction when the write head is at a second radial position, the second radial position closer to an outer diameter of the storage medium than the first radial position.

3. The apparatus of claim 1, wherein the storage device controller is further configured to position the write head in alignment with the center of the target data track for the data write if the target data track is not included in a predefined subset of data tracks.

4. The apparatus of claim 1, wherein the storage device controller positions the write head at the offset from the center of the target data track exclusively when the target data track is included in a predefined subset of alternating data tracks on a storage medium.

5. The apparatus of claim 1, wherein the storage device controller is further configured to retrieve the offset from a firmware table.

6. The apparatus of claim 1, wherein the offset is of greater magnitude when a skew angle of the write head is larger than when the skew angle of the write head is smaller.

7. The apparatus of claim 1, wherein the target data track has a smaller written track width than either directly adjacent data track.

8. A method comprising:

positioning a write head at an offset from a center of a target data track; and

writing data to the target data track with the write head positioned at the offset, the offset selected based on a radial position of a write head at the target data track.

9. The method of claim 8, wherein the offset is in a direction toward an inner diameter of a storage medium when the write head is at a first radial position and the offset is in an opposite direction when the write head is at a second radial position, the second radial position closer to an outer diameter of the storage medium than the first radial position.

10. The method of claim 8, wherein the positioning operation is performed exclusively if the target data track is included in a predefined subset of tracks.

11. The method of claim 10, further comprising:

determining whether the target data track is included in a predefined subset of data tracks; and

if the target data track is not included in the predefined subset of data tracks, positioning the write head to align with the center of the target data track for the data write.

12. The method of claim 10, wherein the predefined subset of tracks includes alternating data tracks on a storage medium.

13. The method of claim 8, wherein the offset is of greater magnitude when a skew angle of the write head is larger than when a skew angle of the write head is smaller.

14. The method of claim 10, wherein the data track has a smaller written track width than either directly adjacent data track.

15. An apparatus comprising:

a storage device controller configured to write data to a first data track with a write head aligned with a center of the first data track, to write data to a second data track with the write head aligned with a center of the second data track, and to write data to a third data track with the write head positioned at a selected offset from a center of the third data track, the third data track between and directly adjacent to the first data track and the second data track.

16. The apparatus of claim 15, wherein the selected offset is selected based on a radial position of the write head at the third data track.

17. The apparatus of claim 15, wherein the selected offset is of greater magnitude when a skew angle of the write head is larger than when a skew angle of the write head is smaller.

18. The apparatus of claim 15, wherein the selected offset is in a direction toward an inner diameter of a storage medium when the write head is at a first radial position and the selected offset is in an opposite direction when the write head is at a second radial position, the second radial position closer to an outer diameter of the storage medium than the first radial position.

19. The apparatus of claim 15, wherein the third data track has a smaller written track width than either of the first data track or the second data track.

20. The apparatus of claim 15, wherein the storage device controller is further configured to retrieve the selected offset from a firmware table responsive to receipt of a command to write data to the third data track.