Servo techniques that mitigate an effect of read and write velocity variations on position error signal calculations
First Claim
1. A data storage tape comprising:
- one or more data tracks; and
a series of servo patterns to facilitate head positioning relative to the data tracks,wherein each of the servo patterns includes a first servo mark, a second servo mark and a third servo mark,wherein at least one of the first servo mark, the second servo mark and the third servo mark is a non-linear servo mark,wherein a distance “
A”
is defined as a first distance in a down-tape direction between the first servo mark and the second servo mark,wherein a distance “
B”
is defined as a second distance in a down-tape direction between the first servo mark and the third servo mark,wherein A/B is linearly related to a cross-tape position at which A and B are defined.
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Accused Products
Abstract
In general, the invention is directed to servo techniques that make use of time-based servo patterns that can substantially mitigate error in a position error signal (PES) calculation resulting from a variation in tape velocity. A servo pattern including at least three marks is written using a single pulse and a single servo head such that the spacing of the servo marks in the servo pattern is not dependent on write velocity. By measuring the time between detection of at least three servo marks in the servo pattern, a ratio of time increments can be used to factor out read tape velocity. In order to facilitate this effect, techniques for determining the relationship between a ratio of time increments and a PES signal are described. Also described are techniques for configuring a servo pattern that provides a linear relationship between a ratio of time increments and a PES signal.
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Citations
20 Claims
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1. A data storage tape comprising:
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one or more data tracks; and a series of servo patterns to facilitate head positioning relative to the data tracks, wherein each of the servo patterns includes a first servo mark, a second servo mark and a third servo mark, wherein at least one of the first servo mark, the second servo mark and the third servo mark is a non-linear servo mark, wherein a distance “
A”
is defined as a first distance in a down-tape direction between the first servo mark and the second servo mark,wherein a distance “
B”
is defined as a second distance in a down-tape direction between the first servo mark and the third servo mark,wherein A/B is linearly related to a cross-tape position at which A and B are defined. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method comprising:
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detecting a first servo mark, a second servo mark and a third servo mark of a servo pattern on a data storage tape with a head, wherein the first servo mark, the second servo mark and the third servo mark have non-identical geometries; and calculating a position error signal according to a cross-tape position of the head relative to the data storage tape according to time intervals between the detection of the first servo mark, the second servo mark and the third servo mark, wherein calculating the position error signal substantially mitigates an error in the calculated position error signal resulting from a variation in velocity of the data storage tape during detection of the first servo mark, the second servo mark and the third servo mark. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A data storage tape comprising:
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one or more data tracks; and a series of servo patterns to facilitate head positioning relative to the data tracks, wherein each of the servo patterns include a first non-linear servo mark and a second non-linear servo mark. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification