Browse Prior Art Database

Adaptive Microjog Slope

IP.com Disclosure Number: IPCOM000123747D
Original Publication Date: 1999-Apr-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 2 page(s) / 81K

Publishing Venue

IBM

Related People

Hashimoto, S: AUTHOR [+3]

Abstract

Disclosed is a technique for improving Soft Error Rate (SER) and reliability of Hard Disk Drive (HDD) by optimizing microjog of each head.

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Adaptive Microjog Slope

   Disclosed is a technique for improving Soft Error Rate
(SER) and reliability of Hard Disk Drive (HDD) by optimizing
microjog of each head.

   HDD used separated write and read element design such as
Magnet Resistive head (MR head) target position at write and read
operation are different by skew angle of head.  It is called
Read-Write offset and its value are calculated by cylinder number
(head radial location).  A Read-Write offset sensitivity to radial
location is fluctuated by head dimension process variation.

   To minimize that sensitivity variation, our method is that
  1.  Using more than two linear regression lines to calculate
      head target position.
  2.  To have independent regression line for each head.

   (Fig. 1) shows the comparison of ideal head location and
calculated value.  In this chart delta of Ideal and Actual line
causes Track miss registration (TMR).  Larger TMR causes worse SER
and decreasing HDD reliability as result.  (Fig. 2) shows that using
one typical slope for all heads, TMR becomes larger by head dimension
variation.  But using optimized slope value for each head, it is
possible to reduce delta between ideal head target and actual seek
target position (see Fig. 3).  And using more than two slopes makes
possible to control more accurate for each head (Fig. 4 is the two
slopes example).