Browse Prior Art Database

Transducer Position Sensor

IP.com Disclosure Number: IPCOM000097937D
Original Publication Date: 1961-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Tsilibes, GN: AUTHOR

Abstract

The left-hand drawing represents a segment of a magnetizable recording disc used as a random access storage in a data processing system. A single addressing of mechanically coupled transducers A and B, separated by a predetermined distance, provides access to two of the several data tracks.

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Transducer Position Sensor

The left-hand drawing represents a segment of a magnetizable recording disc used as a random access storage in a data processing system. A single addressing of mechanically coupled transducers A and B, separated by a predetermined distance, provides access to two of the several data tracks.

Areas of data are periodically separated by patterns of permanently recorded servo patterns. The servo patterns are alternately recorded at different frequencies F1 and F2 and the borderline of the two frequencies defines the centerline of ADDRESS positions 1...3. Transducer A is utilized for data and also to determine whether or not A and B are precisely centered on the data tracks. If A is accurately positioned at ADDRESS 1 as shown, a choice may be made between A or B to provide access to TRACK 1 or 2.

The right-hand drawing shows the manner in which the actual position of A is determined. The signal read by A is a mixture of frequencies F1 and F2. Tuned circuits F1 and F2 filter this signal and each produces an output with an amplitude proportional to the amplitude of the F1 and F2 signals read by A. The F1 and F2 outputs are logically compared in a Difference Amplifier to indicate which way A must be moved to produce F1 and F2 signals of equal amplitude.

The coarse positioning of the transducers may deviate as much as one and one-half data tracks, but fine positioning can still be accomplished. Such a deviation is shown by the dotted representat...