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HDD Pre-Condition method to reduce RRO by STW

IP.com Disclosure Number: IPCOM000015778D
Original Publication Date: 2002-May-26
Included in the Prior Art Database: 2003-Jun-21
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Abstract

This is to reduce servo pattern's RRO, which is caused by non-roughness of disk's rube, by STW (Servo Track Writer).

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HDD Pre-Condition method to reduce RRO by STW

   This is to reduce servo pattern's RRO, which is caused by non-roughness of disk's rube, by STW (Servo Track Writer).

Disk is coated by rube which protects to crush disk and head. The problem, which we faced in early production phase, was that rube condition was changed after servo writing. Rube condition change made RRO bigger and we found higher failure ratio by bad positioning stability at test process. "Pre-condition" is the idea to make change rube condition before servo writing and to reduce RRO problem.

This idea needs STW's positioner which make position head to any tracks. By using this, Pre-condition is done before writing servo pattern and its sequence is shown below.

1. Set lower spindle rotation speed
2. Seek target track by positioner
3. Wait defined time
4. Repeat 2 and 3 until reaches last track
5. Reset spindle rotation speed to normal speed

Rotation speed change (1) makes heads flying height lower and has better effect. Seek width (2) and wait (3) are most important parameter for STW job time. Therefore these parameter are needed to set carefully so that effectiveness and job time are balanced.

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