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Servo-Burst Offset Cancellation Method for Hard Disk Drive

IP.com Disclosure Number: IPCOM000116539D
Original Publication Date: 1995-Sep-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Fukushima, Y: AUTHOR [+2]

Abstract

Disclosed is a method for servo-burst offset cancellation on Hard Disk Drive (HDD).

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Servo-Burst Offset Cancellation Method for Hard Disk Drive

      Disclosed is a method for servo-burst offset cancellation on
Hard Disk Drive (HDD).

      The servo-burst signals have some offset due to magnetic or
electrical noise, non-linearity of peak hold circuit, or electrical
offset.  Those offset causes non-linearity of positioning error
signal.  The method described below can cancel those burst offset by
the microprocessor on HDD.

      The Figure shows the one example of the servo-burst information
on the disk.  Amplitude of Burst-A,B,C is detected by the
microprocessor using A/D convertor.  The microprocessor measures and
calculates the average value of the amplitude for Burst-C during
idling.

      The microprocessor then calculates the positioning error signal
for servo control with offset cancellation.  The following flow shows
this method:
  Idling
  Gray = n + 1 ?
  when yes
  Calculate the average value of Burst-C and store in (c_min)
  Calculation for Positioning Error
  a = (Amplitude of Burst-A) - (c_min)
  b = (Amplitude of Burst-B) - (c_min)
  c = (Amplitude of Burst-C) - (c_min)
  Main positioning error signal(mpes) = a/ (a + b)
  Slave positioning error signal(spes) = c/ (a + b)

This method can also be applied for 4 burst-servo pattern.