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Browse Prior Art Database

Servo Positioning of Magnetic Head

IP.com Disclosure Number: IPCOM000074207D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Commander, RD: AUTHOR

Abstract

A magnetic read/write head in a disk file can be accurately positioned over a selected data track by means of a track-following servo mechanism, not shown, employing a secondary head coupled to the read/write head. Figure 1 shows two adjacent servo tracks A and 8 of fixed frequency, one being the inverse of the other and shifted in phase by 90 degrees.

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Servo Positioning of Magnetic Head

A magnetic read/write head in a disk file can be accurately positioned over a selected data track by means of a track-following servo mechanism, not shown, employing a secondary head coupled to the read/write head. Figure 1 shows two adjacent servo tracks A and 8 of fixed frequency, one being the inverse of the other and shifted in phase by 90 degrees.

The arrangement is such that the read/write head is accurately positioned above a data track when the secondary head is located midway between the corresponding pair of servo tracks A and 8. Figure 2 shows the various composite waveforms derived from the servo head when it is (a) nearer to track A than track 8, (b) midway between track A and track 8 and (c) when it is nearer to track 8 than track A. The position error of the servo head is given by the amplitude and polarity of the DC component of the derived waveform and is used to move the servo head to its correct position midway between tracks when the DC component of the derived composite signal is zero.

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