Spiral write launch while servoing on reference guide spirals

Patent metadata

Field	Value
Publication number	US-2016293192-A1
Application number	US-201514675482-A
Country	US
Kind code	A1
Filing date	Mar 31, 2015
Priority date	Mar 31, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

A reference spiral is written on a recording surface of a hard disk drive. By launching writing of fine guide spirals from a launch point that is disposed on a pre-existing coarse guide spiral, writing of the fine guide spiral can be launched in response to a write head crossing the pre-existing coarse guide spiral, rather than in response to a precisely timed event. To enable launch points being disposed on pre-existing coarse guide spirals, launch points are not all located at the same radial position on the recording surface.

First claim

We claim:

1 . A method of writing fine reference spirals on a recording surface of a magnetic storage device based on locations of coarse reference spirals previously written on a recording surface of the magnetic storage device, said method comprising:
controlling the write head to move to a first write start position on a recording surface of the magnetic storage device and write a first fine reference spiral therefrom; and controlling the write head to move to a second write start position on the recording surface on which the first fine reference spiral is written and write a second fine reference spiral therefrom, wherein the first and second write start positions are at different radial locations.

2 . The method of claim 1 , wherein the recording surface on which the coarse reference spirals are written is a different recording surface of the magnetic storage device than the recording surface on which the first write start position and the second write start position are disposed.

3 . The method of claim 2 , further comprising:
controlling an additional write head to move to a third write start position on an additional recording surface of the magnetic storage device and write a third fine reference spiral therefrom; and controlling the additional write head to move to a fourth write start position on the additional recording and write a fourth fine reference spiral therefrom, wherein the third and fourth write start positions are at different radial locations.

4 . The method of claim 2 , further comprising:
controlling an additional write head to move to a third write start position on the recording surface on which the coarse reference spirals are written and write a third fine reference spiral therefrom; and controlling the additional write head to move to a fourth write start position on the recording surface on which the coarse reference spirals are written and write a fourth fine reference spiral therefrom, wherein the third and fourth write start positions are at different radial locations.

5 . The method of claim 1 , further comprising calculating a radial position for the first write start position based on a slope of a first coarse reference spiral and a target slope of the first fine reference spiral.

6 . The method of claim 5 , further comprising calculating a radial position for the second write start position based on a slope of a second coarse reference spiral and a target slope of the second fine reference spiral.

7 . The method of claim 6 , wherein calculating the radial position for the second write start position is performed after controlling the write head to write the first fine reference spiral.

8 . The method of claim 1 , wherein the first write start position corresponds to an intersection point at which an ideal spiral path corresponding to a first coarse reference spiral crosses a target path for the first fine reference spiral, and the second write start position corresponds to an intersection point at which an ideal spiral path corresponding to a second coarse reference spiral crosses a target path for the second fine reference spiral.

9 . The method of claim 1 , further comprising:
selecting a nominal radial track position, wherein the first write start position corresponds to an intersection point of the nominal radial track position and one of the coarse reference spirals.

10 . The method of claim 1 , wherein controlling the write head to move to the first write start position comprises causing the write head to servo over a radial location corresponding to the first write start position using the coarse reference spirals.

11 . The method of claim 1 , wherein the radial location corresponding to the first write start position also corresponds to an additional write start position for an additional fine reference spiral.

12 . A data storage device, comprising:
a data storage disk with a recording surface; and a controller configured to: control the write head to move to a first write start position on a recording surface of the magnetic storage device and write a first fine reference spiral therefrom; and control the write head to move to a second write start position on the recording surface on which the first fine reference spiral is written and write a second fine reference spiral therefrom, wherein the first and second write start positions are at different radial locations.

13 . The data storage device of claim 12 , wherein the recording surface on which the coarse reference spirals are written is a different recording surface of the magnetic storage device than the recording surface on which the first write start position and the second write start position are disposed.

14 . The data storage device of claim 13 , wherein the controller is further configured to:
control an additional write head to move to a third write start position on an additional recording surface of the magnetic storage device and write a third fine reference spiral therefrom; and control the additional write head to move to a fourth write start position on the additional recording and write a fourth fine reference spiral therefrom, wherein the third and fourth write start positions are at different radial locations.

15 . The data storage device of claim 13 , wherein the controller is further configured to:
control an additional write head to move to a third write start position on the recording surface on which the coarse reference spirals are written and write a third fine reference spiral therefrom; and control the additional write head to move to a fourth write start position on the recording surface on which the coarse reference spirals are written and write a fourth fine reference spiral therefrom, wherein the third and fourth write start positions are at different radial locations.

16 . The data storage device of claim 12 , wherein the controller is further configured to calculate a radial position for the first write start position based on a slope of a first coarse reference spiral and a target slope of the first fine reference spiral.

17 . The data storage device of claim 16 , wherein the controller is further configured to calculate a radial position for the second write start position based on a slope of a second coarse reference spiral and a target slope of the second fine reference spiral.

18 . The data storage device of claim 17 , wherein calculating the radial position for the second write start position is performed after controlling the write head to write the first fine reference spiral.

19 . The data storage device of claim 12 , wherein the first write start position corresponds to an intersection point at which an ideal spiral path corresponding to a first coarse reference spiral crosses a target path for the first fine reference spiral, and the second write start position corresponds to an intersection point at which an ideal spiral path corresponding to a second coarse reference spiral crosses a target path for the second fine reference spiral.

20 . The data storage device of claim 12 , wherein the data storage disk has a plurality of the fine reference spirals written on the recording surface thereof and write start positions of adjacent ones of the fine reference spirals are at different radial positions.

Assignees

• Toshiba Kk

Inventors

• Liang Jiangang
• Szita Gabor
• Huang Tony
• Calfee Gary W

Classifications

• G11B2020/1238

  track, i.e. the entire a spirally or concentrically arranged path on which the recording marks are located · CPC title

• G11B20/1217

  on discs · CPC title

• G11B5/59661 Primary

  Spiral servo format · CPC title

• G11B2020/1281

  Servo information · CPC title

• G11B5/59666 Primary

  Self servo writing · CPC title