Method for magneto-resistive head electrostatic popping detection
AssigneeSamsung Electronics Co., Ltd.
InventorsZhaohui Li, Andrew Kao, Keung Youn Cho
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Abstract
A method and system for detecting electrostatic noise in a magneto-resistive head which may be caused by a plurality of conditions manifesting in the frequency domain as either an amplitude spike or an unstable baseline. In one embodiment, the signals generated by the head when reading a DC-erased track are compared. When viewed in the frequency domain the spectrum gap between the signals is used to determine if the head being tested suffers from defects causing an unstable baseline or from defects causing an amplitude spike.
Claims64
A method for detecting defective heads comprising:
- a) erasing a track on a disk, said disk including a plurality of tracks;
- b) reading said track with a head;
- c) determining a first signal amplitude at a first frequency using a first current supplied to said head;
- d) determining a second signal amplitude at said first frequency using a second current supplied to said head;
- e) determining a first noise measure, said first noise measure to be a function of said first signal amplitude and said second signal amplitude;
- and,
- f) identifying said head as having a first defect type where said first noise measure is greater than a first amplitude threshold.
An apparatus for detecting defective heads comprising:
- a disk connected to a spin stand, said disk including a plurality of tracks;
- a head coupled to said spin stand, said spin stand to cause said head to read from and write to said disk;
- and
- a processor to control said spin stand, said processor to execute computer readable code to:
- a) erase a track on the disk;
- b) read said track with the head;
- c) determine a first signal amplitude at a first frequency using a first current supplied to said head;
- d) determine a second signal amplitude at said first frequency using a second current supplied to said head;
- e) determine a first noise measure, said first noise measure to be a function of said first signal amplitude and said second signal amplitude;
- and,
- f) identify said head as having a first defect type where said first noise measure is greater than a first amplitude threshold.
A computer usable medium having computer readable program code embodied therein to detect defective heads, the computer readable program code in said computer program product to:
- a) erase a track on a disk, said disk to include a plurality of tracks;
- b) read a track on said disk with a head;
- c) determine a first signal amplitude at a first frequency using a first current supplied to said head;
- d) determine a second signal amplitude at said first frequency using a second current supplied to said head;
- e) determine a first noise measure, said first noise measure to be a function of said first signal amplitude and said second signal amplitude;
- f) identify said head as having a first defect type where said first noise measure is greater than a first threshold value;
- g) determine a third signal amplitude at a second frequency using said first current supplied to said head;
- h) determine a fourth signal amplitude at said second frequency using said second current supplied to said head;
- i) determine a second noise measure, said second noise measure to be a function of the third signal amplitude and the fourth signal amplitude;
- and,
- j) identify said head as having a second defect type where said second noise measure exceeds a second amplitude threshold.
An apparatus for detecting defective heads comprising:
- a) means for erasing a track on a disk, said disk including a plurality of tracks;
- b) means for reading said track with a head;
- c) means for determining a first signal amplitude at a first frequency using a first current supplied to said head;
- d) means for determining a second signal amplitude at said first frequency using a second current supplied to said head;
- e) means for determining a first noise measure, said first noise measure to be a function of said first signal amplitude and said second signal amplitude;
- and,
- f) means for identifying said head as having a first defect type where said first noise measure is greater than a first amplitude threshold.
Dependencies are inferred from the claim text.