Single surface in-drive erase

Patent metadata

Field	Value
Publication number	US-9865290-B1
Application number	US-201715453877-A
Country	US
Kind code	B1
Filing date	Mar 8, 2017
Priority date	Mar 8, 2017
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

In an in-drive erase process in a single-surface HDD, erase spirals on the surface being erased can be employed to control writer position. A reader-to-writer timing offset value is determined for a plurality of radial locations on the surface to be erased, and an erase window is determined for a radial location disposed between two erase spirals. The erase window includes an erase start time, which is based on a spiral exit time of a reader and the reader-to-writer timing offset value for the radial location, and an erase stop time, which is based on a spiral encounter time of the reader and the reader-to-writer timing offset value. The erase window prevents complete erasure of erase spirals, so that the servo system of the HDD can continue to servo off of the erase spirals. The erase spirals may be written with a lower slope than conventional spiral tracks.

First claim

We claim:

1. A method of erasing a data recording surface of a data storage device, the method comprising:
controlling a writer to write a spiral track on the data recording surface; and
while controlling the writer at a radial location on the data recording surface based on time and position information included in the spiral track, controlling the writer to write an erase pattern on the data recording surface by:
(i) determining a spiral encounter time at which a reader associated with the writer will cross a leading edge of the spiral track at the radial location;
(ii) determining an erase stop time based on the spiral encounter time and a reader-to-writer timing offset value; and
(iii) controlling the writer to discontinue writing the erase pattern at the erase stop time.

2. The method of claim 1 , wherein the reader-to-writer timing offset value is a function of the radial location of the reader.

3. The method of claim 1 , wherein the reader-to-writer timing offset value is a function of a radial offset between the writer and the reader and a circumferential offset between the writer and the reader.

4. The method of claim 1 , further comprising:
determining a spiral exit time at which the reader will cross a trailing edge of an adjacent spiral track that immediately precedes the spiral track;
determining an erase start time based on the spiral exit time and the reader-to-writer timing offset value; and
controlling the writer to continue writing the erase pattern at the erase start time.

5. The method of claim 4 , wherein determining the erase start time based on the spiral exit time and the reader-to-writer timing offset value comprises selecting the erase start time to occur a certain time interval earlier than a time indicated by modifying the spiral exit time with the reader-to-writer timing offset value.

6. The method of claim 5 , wherein determining the erase start time based on the spiral encounter time and the reader-to-writer timing offset value comprises selecting the erase start time to occur when the writer is disposed over a portion of the adjacent spiral track.

7. The method of claim 1 , wherein a signal frequency associated with the spiral track is a different frequency than any signal frequency associated with patterns previously written on the data recording surface.

8. The method of claim 7 , wherein the patterns written on the data recording surface include at least one of spiral tracks, product wedges, other servo data, or user data.

9. The method of claim 1 , wherein the erase pattern is written at the radial location for multiple revolutions of the data recording surface.

10. The method of claim 1 , wherein determining the erase stop time based on the spiral encounter time and the reader-to-writer timing offset value comprises selecting the erase stop time to occur a certain time interval later than a time indicated by modifying the spiral encounter time with the reader-to-writer timing offset value.

11. The method of claim 1 , wherein determining the erase stop time based on the spiral encounter time and the reader-to-writer timing offset value comprises selecting the erase stop time to occur when the writer is disposed over a portion of the spiral track.

12. The method of claim 1 , wherein controlling the writer to write the spiral track on the data recording surface comprises controlling the radial motion of the writer at a radial velocity that is no greater than 100 millimeters per second.

13. A data storage device comprising:
a rotatable disk with a writable surface; and
a controller configured to:
control a writer to write a spiral track on the writable surface; and
while controlling the writer at a radial location on the writable surface based on time and position information included in the spiral track, control the writer to write an erase pattern on the writable surface by:
(i) determining a spiral encounter time at which a reader associated with the writer will cross a leading edge of the spiral track at the radial location;
(ii) determining an erase stop time based on the spiral encounter time and a reader-to-writer timing offset value; and
(iii) controlling the writer to discontinue writing the erase pattern at the erase stop time.

14. The data storage device of claim 13 , wherein the reader-to-writer timing offset value is a function of the radial location of the reader.

15. The data storage device of claim 13 , wherein the reader-to-writer timing offset value is a function of a radial offset between the writer and the reader and a circumferential offset between the writer and the reader.

16. The data storage device of claim 13 , further comprising:
determining a spiral exit time at which the reader will cross a trailing edge of an adjacent spiral track that immediately precedes the spiral track;
determining an erase start time based on the spiral exit time and the reader-to-writer timing offset value; and
controlling the writer to continue writing the erase pattern at the erase start time.

17. The data storage device of claim 16 , wherein determining the erase start time based on the spiral exit time and the reader-to-writer timing offset value comprises selecting the erase start time to occur a certain time interval earlier than a time indicated by modifying the spiral exit time with the reader-to-writer timing offset value.

18. The data storage device of claim 17 , wherein determining the erase start time based on the spiral encounter time and the reader-to-writer timing offset value comprises selecting the erase start time to occur when the writer is disposed over a portion of the adjacent spiral track.

19. The data storage device of claim 13 , wherein a signal frequency associated with the spiral track is a different frequency than any signal frequency associated with patterns previously written on the data recording surface.

20. The data storage device of claim 13 , wherein determining the erase stop time based on the spiral encounter time and the reader-to-writer timing offset value comprises selecting the erase stop time to occur a certain time interval later than a time indicated by modifying the spiral encounter time with the reader-to-writer timing offset value.

Assignees

• Toshiba Kk

Inventors

• Liang Jiangang
• Liu Ting-Chun Janet
• Calfee Gary W

Classifications

• G11B5/024

  Erasing · CPC title

• G11B5/012

  Recording on, or reproducing or erasing from, magnetic disks (G11B17/00, G11B19/00 take precedence) · CPC title

• G11B5/59661 Primary

  Spiral servo format · CPC title