Browse Prior Art Database

Hard Disk Drive Servo Track Writing Method with Adaptive Write Current

IP.com Disclosure Number: IPCOM000118832D
Original Publication Date: 1997-Jul-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 92K

Publishing Venue

IBM

Related People

Asano, H: AUTHOR [+3]

Abstract

Disclosed is a servo track writing method for Hard Disk Devices (HDDs) with adaptive write current induced into the recording head. The optimization is performed on each disk surface banded into several recording zones prior to the servo writing. The servo pattern is after written by the desired current referring to the optimization result. The objective is to improve linearity of the Position Error Signal (PES) to make smooth and accurate head positioning with covering wider track offset range.

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Hard Disk Drive Servo Track Writing Method with Adaptive Write Current

      Disclosed is a servo track writing method for Hard Disk Devices
(HDDs) with adaptive write current induced into the recording head.
The optimization is performed on each disk surface banded into
several recording zones prior to the servo writing.  The servo
pattern is after written by the desired current referring to the
optimization result.  The objective is to improve linearity of the
Position Error Signal (PES) to make smooth and accurate head
positioning with covering  wider track offset range.

      This disclosure introduces two methods for the
optimization.  Both methods are based on measuring the saturation
curve of the write current vs. read-back amplitude sensitivity.
Conventional Servo Track Writer (STW) can perform on both methods
through the process  (Fig. 1).  The functional requirements for STW
are an anti-vibration, a system clock generator synchronous to the
disk revolution, a fine positioner, a read/write channel and a read
signal amplitude detector.

      The first method determines the optimal write current at a
point of the desired amplitude, which is obtained by multiplying a
constant k and the maximum value of the saturation curve.  The
constant k is set off-line as a head-media unique value.  The typical
value is in between 0.7 and 0.95.  The saturation curve is traced by
measuring the averaged amplitude of the read back burst signal at
each write curr...