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Browse Prior Art Database

Track Following Pattern and Detection

IP.com Disclosure Number: IPCOM000074358D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Gibeau, FC: AUTHOR [+2]

Abstract

To track follow, patterns must be written on the disk or other recording media that will facilitate obtaining a signal that is proportional to the position with respect to the track center. This circuit provides a pattern and detection method in which alternate bursts of AC and DC flux are written on the servo surface. The AC burst on an odd track is adjacent to the DC burst on an even track. In addition to the timing of the AC bursts, odd and even tracks are distinguished by the fact that AC bursts on an even track begin with a positive transition and AC bursts on an odd track begin with a negative transition. The bursts are written so that when reading the two tracks, a gap will be presented between the bursts of AC signals generated from the two tracks.

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Track Following Pattern and Detection

To track follow, patterns must be written on the disk or other recording media that will facilitate obtaining a signal that is proportional to the position with respect to the track center. This circuit provides a pattern and detection method in which alternate bursts of AC and DC flux are written on the servo surface. The AC burst on an odd track is adjacent to the DC burst on an even track.

In addition to the timing of the AC bursts, odd and even tracks are distinguished by the fact that AC bursts on an even track begin with a positive transition and AC bursts on an odd track begin with a negative transition. The bursts are written so that when reading the two tracks, a gap will be presented between the bursts of AC signals generated from the two tracks.

The drawing shows a system configuration fur the detection of servo information which was recorded in the above manner. The read signal from servo head 1 indicates the position of the servo head with respect to the servo track on the magnetic disk 2. The read signal from the servo head is fed into a preamplifier 3 and then into an automatic gain circuit 4. Waveform A shows the output of the AGC amplifier under the condition that the servo head is not in the desired position. It should be noted that the signal received by the servo head is alternating bursts of AC signals, with the odd bursts being of a first amplitude and the even bursts being of a second amplitude. The out...