Browse Prior Art Database

Servo Control of Multielement Magnetic Heads

IP.com Disclosure Number: IPCOM000077793D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Zimmermann, V: AUTHOR [+2]

Abstract

With magnetic multiple heads produced in vapor deposition technology, the individual head elements are essentially wider than the associated air gap lengths. The resulting reduction in the track density on the record carrier is eliminated by arranging the head elements at a spacing equal to two data tracks, with track adjustment being servo-controlled.

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Servo Control of Multielement Magnetic Heads

With magnetic multiple heads produced in vapor deposition technology, the individual head elements are essentially wider than the associated air gap lengths. The resulting reduction in the track density on the record carrier is eliminated by arranging the head elements at a spacing equal to two data tracks, with track adjustment being servo-controlled.

Fig. 1 shows a part of a multiple head 1 with several data head elements 2 and the associated pole pieces 3, as well as a servo head element 4 with pole piece 5. The spacing between the data head elements is equal to twice the track width d. In comparison with this, the spacing between the servo head element and the respective adjacent data head element is 2.5 d. Multiple head 1 scans data tracks 6 and the three servo tracks 7. For each data head element 2, two adjacent data tracks a and b are provided. With pole piece 5 of servo head element 4 being positioned between the left and the center servo track, pole pieces 3 of the various data head elements 2 are above the data tracks marked
a. With pole piece 5 being positioned on the other hand between the center and the right servo track, the data tracks marked b are scanned by pole pieces 3.

It is also possible for two such multiple heads to be arranged in tandem on a common access carriage. The multiple heads can be shifted against each other. During normal operation they are staggered in relation to each other by the width of one track, i.e., data tracks a and b are scanned by one and the other multiple head, respectively, thus reducing the access time. If one head element fails, the associated data track can be scanned by a head element of the other multiple head, with the latter being shifted by the width of one track as shown in Fig. 1. During writing, the two multiple heads are arranged one immediately behind the other without an...