Detecting touch down and/or assessing quality in a hard disk drive
AssigneeSeagate Technology International
InventorsShungChang Lee, Brian Thornton, Mike Suk, SeungMo Kang
Life of this patent
Estimating the term…
Abstract
This application discloses a hard disk drive and a control circuit that are configured to determine touchdown by determining the SAGC for a track, removing the repeatable component of the SAGC to create the non-repeatable component and determining an indication of clearance irregularity and/or touch down when the standard deviation of the non-repeatable component spikes. These operations may create a defect map and/or a Flying height On Demand (FOD) control table in or for the hard disk drive as products of operating the hard disk drive.
Claims25
A hard disk drive, comprising:
- a disk base;
- a spindle motor mounted on said disk base and rotably coupled to at least one disk to create at least one rotating disk surface including multiple tracks each intersecting multiple servo wedges at an Amplitude Gain Control (AGC) calibration pattern;
- a head stack assembly pivotably mounted by an actuator pivot to said disk base and configured position a slider on said rotating disk surface to read said AGC calibration pattern to create a read AGC pattern signal;
- and
- a control circuit configured to
- receive a version of said read AGC pattern signal to create a Servo AGC (SAGC) sequence for said track,
- process said SACG sequence for said track to remove a repeatable component of said SAGC sequence to create a non-repeatable SAGC component,
- calculate a standard deviation for said non-repeatable SAGC component, and
- determine touch down of said slider on said rotating disk surface based upon said standard deviation exceeding a predetermined amount.
A control circuit for use in a hard disk drive, comprising:
- said control circuit configured to
- receive a version of a read Amplitude Gain Control (AGC) pattern signal to create a Servo AGC (SAGC) sequence for a track intersecting multiple servo wedges at an AGC calibration pattern read by a slider positioned over said track to create said read AGC pattern signal,
- process said SACG sequence for said track to remove a repeatable component of said SAGC sequence to create a non-repeatable SAGC component,
- calculate a standard deviation for said non-repeatable SAGC component, and
- determine touch down of said slider on said rotating disk surface based upon said standard deviation exceeding a predetermined amount.
A method, comprising the step of:
- operating a hard disk drive that positions a slider over a track on a rotating disk surface to create a touch down flag, with said track intersecting multiple servo wedges at an Amplitude Gain Control (AGC) calibration pattern;
- and
- operating a control circuit within said hard disk drive and in communication with said slider to create said touch down flag, further comprising the steps of:
- receiving a version of said read AGC pattern signal to create a Servo AGC (SAGC) sequence for said track,
- processing said SACG sequence for said track to remove a repeatable component of said SAGC sequence to create a non-repeatable SAGC component,
- calculating a standard deviation for said non-repeatable SAGC component, and
- determining touch down of said slider on said rotating disk surface based upon said standard deviation exceeding a predetermined amount to create said touch down flag.
Dependencies are inferred from the claim text.