Method and structure for improving performance and storage density in a data storage device
View Patent ↗A data storage device with improved data storage densities, coupled with lower hard error and write-inhibit events is described. A feed-forward write inhibit (FFWI) method enables data tracks to be written more densely. Alternatively, the FFWI method may reduce the hard error and write inhibit events to improve data storage performance. A concept of virtual tracks enables the FFWI method to be applied to the writing of circular data tracks with non-circular servo tracks, or to the writing of non-circular data tracks with PES data from circular servo tracks—in both cases, improvements to performance and/or storage densities are enabled. The FFWI method may also be applied to the case of both non-circular servo and data tracks.
1. A method for writing data in a data storage device comprising:
a rotating data storage medium, comprising:
data tracks;
servo data sectors, comprising servo burst patterns;
a read/write head assembly, comprising a read head configured to read data from the rotating data storage medium, and a write head configured to write data to the rotating data storage medium; and
a controller for controlling position of the read/write head assembly relative to the rotating data storage medium, wherein the controller is configured to receive positional error signals from the read head generated when the read head passes over a servo burst pattern;
the method comprising:
defining a multiplicity of servo tracks on the rotating data storage medium;
determining a desired pattern of data tracks to be written on the data storage medium, the desired pattern comprising radial spacings of the data tracks;
defining a coordinate system for the data tracks based on the positional error signals of the multiplicity of servo tracks; and
writing data to the rotating storage medium into a data track, wherein a location of the data track is determined using the coordinate system, and wherein at least one of a shape of the data track and a shape of the servo track is non-circular.
2. The method of claim 1 , wherein both the servo tracks and data tracks are substantially non-circular.
3. The method of claim 1 , wherein the servo tracks and data tracks overlap circumferentially around the rotating data storage medium.
4. The method of claim 1 , wherein there is a more than one data track for each servo track.
5. The method of claim 1 , wherein the data track is defined by a function fitted to the positional error signals.
6. The method of claim 5 , wherein the function is a polynomial.
7. The method of claim 5 , wherein the function is a harmonic of a single rotation of the rotating data storage medium.
8. The method of claim 7 , wherein the harmonic is a first-harmonic of a single rotation of the rotating data storage medium.
9. The method of claim 5 , wherein local slope of the virtual data track is used to generate local values for desired spacing between data tracks to be written on the rotating data storage medium by the write head.
10. A method for writing data in a data storage device comprising:
a rotating data storage medium, comprising:
data tracks;
servo data sectors, comprising servo burst patterns;
a read/write head assembly, comprising a read head configured to read data from the rotating data storage medium, and a write head configured to write data to the rotating data storage medium; and
a controller for controlling a position of the read/write head assembly relative to the rotating data storage medium, wherein the controller is configured to receive positional error signals from the read head generated when the read head passes over a servo burst pattern;
the method comprising:
defining a multiplicity of servo tracks on the rotating data storage medium;
determining a desired pattern of data tracks to be written on the data storage medium, the desired pattern comprising the radial spacings of the data tracks;
defining a coordinate system for the data tracks based on the positional error signals of the multiplicity of servo tracks; and
writing data to the rotating storage medium into a data track, wherein a location of the data track is determined using the coordinate system, and wherein both a shape of the data track and a shape of the servo track are substantially non-circular.
11. The method of claim 10 , wherein the servo tracks and data tracks overlap circumferentially around the rotating data storage medium.
12. The method of claim 10 , wherein there is a more than one data track for each servo track.
13. The method of claim 10 , wherein the data track is defined by a function fitted to the positional error signals.
14. The method of claim 13 , wherein the function is a polynomial.
15. The method of claim 13 , wherein the function is a harmonic of a single rotation of the rotating data storage medium.
16. A method for writing data in a data storage device comprising:
a rotating data storage medium, comprising:
data tracks;
servo data sectors, comprising servo burst patterns;
a read/write head assembly, comprising a read head configured to read data from the rotating data storage medium, and a write head configured to write data to the rotating data storage medium; and
a controller for controlling the position of the read/write head assembly relative to the rotating data storage medium, wherein the controller is configured to receive positional error signals from the read head generated when the read head passes over a servo burst pattern;
the method comprising:
defining a multiplicity of servo tracks on the rotating data storage medium;
determining a desired pattern of data tracks to be written on the data storage medium, the desired pattern comprising the radial spacings of the data tracks;
defining a coordinate system for the data tracks based on the positional error signals of the multiplicity of servo tracks; and
writing data to the rotating storage medium into a data track, wherein the location of the data track is determined using the coordinate system, wherein both a shape of the data track and a shape of the servo track are substantially non-circular, wherein there is a more than one data track for each servo track, and wherein the data track is defined by a function fitted to the positional error signals.
17. The method of claim 16 , wherein the data track is defined by a polynomial function fitted to the positional error signals.
18. The method of claim 16 , wherein the function is a harmonic of a single rotation of the rotating data storage medium.