Servo burst pattern defect detection
AssigneeSeagate Technology LLC
InventorHieu V. Nguyen
Life of this patent
Estimating the term…
Abstract
Apparatus and method for improving operational performance of a disc drive by detecting defective servo burst patterns. A rotatable disc is provided with servo data which include a plurality of servo burst patterns to define a plurality of tracks. A head transduces the burst patterns to provide burst signals to a servo circuit which controllably positions the head with respect to the surface of the disc by determining a position error signal from a combination of the burst signals. The servo circuit identifies a selected servo burst pattern as defective in relation to differences between absolute values of successive pairs of peak amplitude samples from the burst signal.
Claims12
In a disc drive having a rotatable disc on which servo data are stored to enable a servo circuit of the disc drive to position a head relative to the disc, the servo data including a position field comprising a plurality of burst patterns from which burst signals are transduced, the servo circuit sampling and combining the burst signals to generate a position error signal indicative of the position of the head with respect to a corresponding track, a method for detecting a defective burst pattern comprising steps of:
- (a) determining a sequence of servo burst amplitude samples indicative of peak amplitudes of a servo burst signal obtained from a selected burst pattern;
- (b) determining a sequence of difference values in relation to differences between absolute values of successive pairs of the servo burst amplitude samples from step (a);
- (c) comparing the sequence of difference values to a defect threshold;
- and
- (d) identifying the selected burst pattern as defective when at least one of the difference values exceeds the defect threshold.
A disc drive, comprising:
- a head supported adjacent a surface of a rotatable disc on which servo data are stored, the servo data including a plurality of servo burst patterns which define a plurality of tracks;
- a servo circuit, responsive to the head, which controllably positions the head with respect to the surface of the disc in relation to a position error signal determined from a combination of burst signals transduced from the servo burst patterns, the servo circuit identifying a selected servo burst pattern as defective in relation to differences between absolute values of successive pairs of peak amplitude samples from the burst signal obtained from the selected servo burst pattern.
A disc drive, comprising:
- a head supported adjacent a surface of a rotatable disc on which servo data are stored, the servo data including a plurality of servo burst patterns which define a plurality of tracks;
- and
- defect detection means for detecting a defective servo burst pattern in relation to a burst signal transduced by the head solely from said defective servo burst pattern.
Dependencies are inferred from the claim text.