Browse Prior Art Database

Servo Concept for Buried Servo Without Use of Dual Gap Heads

IP.com Disclosure Number: IPCOM000048061D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Lissner, RW: AUTHOR [+2]

Abstract

It is difficult to accomplish reliable servo read while writing data with the same read/write (R/W) head element. A similar problem exists if a dual-gap head is used which has elements in close proximity to each other. This causes crosstalk by electromagnetic pickup and transformer coupling. To avoid both of these problems, it is necessary to have separate gaps which are spaced a sufficient distance from each other, or shielding. In each case, it is necessary to select (or switch) to the head which has access to the desired data area for two reasons: to be able to read or write data, and read servo information.

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Servo Concept for Buried Servo Without Use of Dual Gap Heads

It is difficult to accomplish reliable servo read while writing data with the same read/write (R/W) head element. A similar problem exists if a dual-gap head is used which has elements in close proximity to each other. This causes crosstalk by electromagnetic pickup and transformer coupling. To avoid both of these problems, it is necessary to have separate gaps which are spaced a sufficient distance from each other, or shielding. In each case, it is necessary to select (or switch) to the head which has access to the desired data area for two reasons: to be able to read or write data, and read servo information.

The new concept disclosed here adds no additional hardware requirements. Instead of addressing (or switching) to the head which handles data, to read servo information, the opposite head is used to obtain servo information. Fig. 1 shows one possible embodiment using four heads for two disk surfaces. However, this new concept can be utilized for any number of heads greater than two. When head 1 is used as data R/W head, head 3 always becomes the servo read head. The same is done with the other heads. They are always used in pairs so that the same dimensional relationship exists, heads 2 and 4, for example. Exact alignment is not necessary because their dimensional relationship does not change. In addition, any particular head pair (one being used as servo read head and the other as data R/W head) are on the same dis...