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Overwrite Compensation Method for a Hard Disk Drive

IP.com Disclosure Number: IPCOM000013860D
Original Publication Date: 1999-Dec-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 1 page(s) / 28K

Publishing Venue

IBM

Related People

Masahiro Shimizu: AUTHOR [+4]

Abstract

Disclosed is a method to compensate poor overwrite performance at a low temperature for a Hard Disk Drive (HDD). The overwrite performance generally becomes worse at the low temperature, which depends on a write head and a d performance.

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Overwrite Compensation Method for a Hard Disk Drive

Disclosed is a method to compensate poor overwrite performance at a low temperature for a Hard Disk Drive (HDD).
The overwrite performance generally becomes worse at the low temperature, which depends on a write head and a d
performance.

And it becomes difficult to read a data that is written in the poor overwrite situation.
Increasing the write current can improve the performance at that time.

A thermal sensor helps to apply the higher write current by sensing the low temperature.

And it is possible to forecast the overwrite performance of one write head at low temperature by using a special
pattern and an accumulator of errors in a manufacturing process.

Compensation method is the following.

In the manufacturing process,

1. Measure the overwrite performance index which shall be normalized with an atmosphere temperature.
2. Store the index value on a disk by heads. Or change the default value of the write current that depends on th
value, if needed.

In normal use,

3. Increase or decrease the write current that depends on the temperature and the index value of a selected head

The following Fig.1 is an example circuit using the thermal sensor that is resistance type. A capacitance type i
available.

And the temperature is calculated from the value of an Analog Digital Converter in consideration of non-linearit
sensor output.

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