Browse Prior Art Database

Track Following Servo System Employing Discrete Tracks Having Boundary Displacements

IP.com Disclosure Number: IPCOM000081381D
Original Publication Date: 1974-May-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Nystrom, W: AUTHOR

Abstract

This track following system obtains its track following position signal from the data signal recorded on discrete data tracks on a magnetic disk.

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Track Following Servo System Employing Discrete Tracks Having Boundary Displacements

This track following system obtains its track following position signal from the data signal recorded on discrete data tracks on a magnetic disk.

Each discrete data track is formed such that it had its edges modulated with a frequency f, as shown in Fig. 1. Data track 1 is shown as having its modulated shape.

Read/write head 2 has a write element 9 which writes the entire area of the discrete track including the modulated edges. The read element 10 of read/write head 2 is narrow enough so as to read a data signal from the center of the discrete track 1, without sensing the modulation caused by the outer edges of data track 1. The signal read by the read transducer 2 is passed through the read preamplifier 3 to the read channel where the data is sensed.

The output of read preamplifier 3 is also fed to demodulator 4, which extracts the data component from the signal being read by preamplifier 3. It can readily be realized that if the read element 10 is centered on track 1, then there will be no output of the demodulator 4. However, if read element 10 is offset either to the left or to the right, there will be a frequency component of frequency f, having a phase indicative of the direction of displacement of read element 2 with relationship to the center of discrete track 1. The output of demodulator 4 is, therefore, compared with an oscillator 5, which is synchronized to the rotati...