Browse Prior Art Database

MR HEAD MEASUREMENT METHOD

IP.com Disclosure Number: IPCOM000014075D
Original Publication Date: 2001-May-29
Included in the Prior Art Database: 2003-Jun-19
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Abstract

Disclosed is magnetic write and read head width measurement method by using servowriter which has the positioning system to make actuator move so that read the signals around the disk as well as write/read function electronics. Write an amplitude burst pattern in FIG-1 at certain pitch (TP1) After writing several tracks, go back to the original track and read the signals written before. Assuming that 1st written burst is A, 2nd, 3rd for B and C respectively, there are the location where A amplitude is the same as C. At the location, read A,B,C burst amplitude and compute APC1. (FIG-2) After erasing the written burst, write burst again with little different pitch(TP2) than 1st time. Read back again, and compute the APC2. (FIG-3) In general, the relation between Track pitch and read/write head width is expressed as formula (1)

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MR HEAD MEASUREMENT METHOD

Disclosed is magnetic write and read head width measurement method by using servowriter

which has the positioning system to make actuator move so that read the signals around

the disk as well as write/read function electronics.

Write an amplitude burst pattern in FIG-1 at certain pitch (TP1) After writing several tracks, go back to the original track and read the signals written before. Assuming that 1st written burst is A, 2nd, 3rd for B and C respectively, there are the location where A amplitude is the same as C. At the location, read A,B,C burst amplitude and compute APC1. (FIG-2) After erasing the written burst, write burst again with little different pitch(TP2) than 1st time. Read back again, and compute the APC2. (FIG-3) In general, the relation between Track pitch and read/write head width is expressed as formula (1)

TP = Ww + (1-APC) x Wr (1)

Where

Ww = Write head width

Wr = Read head width

According to the formula (1), each of the measurement results are expressed as follows.

TP1 x 2=·Ww + (1-APC1)·x Wr (2) TP2 x 2·=·Ww +·(1-APC2)·x·Wr (3)

TP1 and TP2 is the known value which are the write burst pitch defined by positioner system. Both Ww and Wr are obtained by solving (2) and (3).

TP 1

DISK ROTATION

Track direction

FIG -1

1

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TP 1 x 2

A B C

A+C

B

=A P C 1

FIG -2

TP 2 x 2

A B C

A+C

B

=A P C 2

FIG -3

2

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