Browse Prior Art Database

Compensation for Element to Element Misregistration in a Dual Element Head

IP.com Disclosure Number: IPCOM000081521D
Original Publication Date: 1974-Jun-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 37K

Publishing Venue

IBM

Related People

Schwarz, TA: AUTHOR

Abstract

Fig. 1 shows a read/write head 1 which has a separate read element 3 and write element 2. The head 1 coacts with magnetic track 4 and causes a read/write area 5 to be utilized in track 4 by the read/write operation of head 1. It can be appreciated that any misregistration between the reading and writing operation, such that the center line between the read or write element does not appear to be the same and causes the read element to not be centered over the read/write area, decreases the signal-to-noise ratio during the read operation.

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Compensation for Element to Element Misregistration in a Dual Element Head

Fig. 1 shows a read/write head 1 which has a separate read element 3 and write element 2. The head 1 coacts with magnetic track 4 and causes a read/write area 5 to be utilized in track 4 by the read/write operation of head 1. It can be appreciated that any misregistration between the reading and writing operation, such that the center line between the read or write element does not appear to be the same and causes the read element to not be centered over the read/write area, decreases the signal-to-noise ratio during the read operation.

Fig. 2 shows one mechanism which causes the center line between the write element 2 and read element 3 to be different. This misregistration is caused by skewing the read/write head assembly 1 with respect to the magnetic track 4. As can be seen in Fig. 2, this will cause the write area 7 to be different than the read area 6.

A second mechanism of misregistration is due to misregistration of the center line between the two elements during the manufacturing process. This is shown in Fig. 3, and again it can be seen that the read area 6 and write area 7 associated with read/write head 1 and data track 4 are different.

It can be realized that in many cases both of the mechanisms shown in Figs. 2 and 3 are present at the same time, therefore, greatly increasing the misregistration, and thereby greatly decreasing the signal-to-noise ratio of the system. It would, therefore, be desirous to have read area 6 exactly overlap write area 7 regardless of any misregistration, due to either the skew or tolerance of the combination or both.

A method for providing such a correction is accomplished by having within each data track 8, as shown in Fig. 4, a small prerecorded test section 9 within that data track. When a read/write element 1 is first mounted into the system, both the write element 2 and read element 3 are connected to separate read circuitry. The read and write elements are thereafter caused to...