Adaptive Write-Inhibit Architecture

Adaptive Write-Inhibit Architecture

      Disclosed is a Hard Disk Drive which has an adaptive
write-inhibit criteria for each head.  With a higher recording
density and a multiple source of heads and disks, write-width
tolerance of each head cannot be ignored.  Thus, a write-width
screening test was implemented to protect data lost from squeeze
write of an adjacent track  (Figure).  To achieve a higher
manufacturing yield and assure Hard Disk  Drive quality, adjust write
inhibit criteria by each head and disk combination in the
manufacturing test process.

The following describes the basic concepts of this article:
  1.  Prepare a table for the write inhibit value of each head
       on the disk.
  2.  Measure write width of each head in a manufacturing test
       process.
      If write width of a head is narrower than design
       target, then set
        Write Inhibit = Default value + A (value A can be
         changed by program)
      If write width of a head is wider than design target,
       then set
        Write Inhibit = Default value - A (value A can be
         changed by program)
  3.  Do Write Width Screening Test for each head.
      If a head is failed at the Write Width Screening test,
       then set
        Write Inhibit = Write Inhibit - B (value B can be changed
         by program)
      and do Write Width screening Test again.

      T...