Browse Prior Art Database

Automatic Magnetic Track Seeking System

IP.com Disclosure Number: IPCOM000092969D
Original Publication Date: 1967-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Hagopian, JJ: AUTHOR

Abstract

This system automatically selects and servos a transducer, such as a magnetic head, to a prescribed magnetic track on a stationary record such as a magnetic chip. A reference track is recorded at the edge of the record perpendicular to the information tracks. Head positioning is effected by circuitry which uses the reference track and the signal from its reference head as input.

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Automatic Magnetic Track Seeking System

This system automatically selects and servos a transducer, such as a magnetic head, to a prescribed magnetic track on a stationary record such as a magnetic chip. A reference track is recorded at the edge of the record perpendicular to the information tracks. Head positioning is effected by circuitry which uses the reference track and the signal from its reference head as input.

Magnetic chip 10 contains information tracks 12 and reference track 14. The latter is recorded at the end of chip 10 perpendicular to a band of, for instance, 100 tracks 12. Track 14 is prerecorded, preferably as part of the chip fabrication process, with a magnetic pattern which reverses polarity at the exact centers of tracks 12. Heads 16 and 18 are mechanically linked for movement together in the direction of arrow 20. Head 18 is also free to move along any track 12 on which it is positioned.

Oscillator 22 is divided to supply excitation to head 16 atterminals 24 and provides a reference signal to phase detector 26. The AM 200 kc output of head 16, as it moves along track 14, is amplified and fed to phase modulator 28. The latter provides another input to detector 26.

The output of head 16 is zero when the center of its gap is directly above the magnetization transition points of track 14. With displacements in either direction, its output changes phase by 180 degrees and its amplitude increases proportionally. Depending on whether head 16 is sen...