Detecting touch down and/or assessing quality in a hard disk drive

a hard disk drive and touch down technology, applied in the field/or assessing quality in hard disk drives, can solve the problems of narrow clearance tolerances, affecting the accuracy of detecting touch down,

Inactive Publication Date: 2013-07-04
SEAGATE TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This method effectively detects touch down and assesses quality by stabilizing clearance irregularity detection, enabling reliable operation and quality management in manufacturing and operation of hard disk drives at low clearances.

Problems solved by technology

The need to know when touch down occurs has been a long term concern, but the problems of detecting touch down have worsened as clearance tolerances have narrowed.
What works well at a clearance of ten nanometers (nm) may be too erratic for clearances below three nm.
For instance, in the past touchdown could be determined by considering the average SAGC for different power levels of FOD control, but this has been found unreliable at low clearances.

Method used

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  • Detecting touch down and/or assessing quality in a hard disk drive
  • Detecting touch down and/or assessing quality in a hard disk drive
  • Detecting touch down and/or assessing quality in a hard disk drive

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Embodiment Construction

[0021]This invention relates to detecting touch down and / or assessing quality in hard disk drives. It discloses a hard disk drive, a control circuit and a processor that 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.

[0022]Referring to the drawings more particularly by reference numbers, FIG. 1 shows an example of an embodiment of the invention as a hard disk drive 10 including a disk base to which a spindle motor 14 is mounted with at least one disk 12 coupled to the spindle motor to create a rotating disk surface 6. A voice coil motor 46 includes a head stack assembly 48 pivotably mounted by an actuator pivot 40 to the disk base, responsive to its voice coil 42 interacting with a fixed magnetic assembly 44 mounted on the disk base to pivot a head gi...

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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.

Description

TECHNICAL FIELD[0001]This invention relates to detecting touch down and / or assessing quality in hard disk drives.BACKGROUND OF THE INVENTION[0002]Hard disk drives access data stored on their disk surfaces by positioning a slider containing a read-write head over a track on one of the disk surfaces. They require careful control of the clearance of the slider over the accessed disk surface to insure the reliability of reading and writing the data. Since the incorporation of Flying height On Demand (FOD) capabilities, tables of FOD control values for various zones of tracks on the disk surface are often used. These tables may list an extreme control value, after which the slider experiences Head to Disk Contact, which is referred herein as Touch Down (TD).[0003]The tracks of the disk surface are often organized into servo wedges radiating from the disk drive's spindle hub. Each servo wedge contains a servo region separating a user data region from the user data region of a neighboring ...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): G11B27/36
CPCG11B5/6029G11B27/36G11B19/048G11B5/6076
InventorLEE, SUNG CHANGTHORNTON, BRIANSUK, MIKEKANG, SEUNG MO
OwnerSEAGATE TECH LLC