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Browse Prior Art Database

Magnetic Head Position Sensing

IP.com Disclosure Number: IPCOM000079949D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 57K

Publishing Venue

IBM

Related People

Bush, HE: AUTHOR [+2]

Abstract

This method and apparatus determines the accuracy and proper adjustment of a stepper motor 10, acting through a lead screw 12 for positioning a magnetic sensing head 14 on a magnetic disk 16, by providing s feedback signal which peaks about the center of the track regardless of whether or not the disk is being driven concentrically.

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Magnetic Head Position Sensing

This method and apparatus determines the accuracy and proper adjustment of a stepper motor 10, acting through a lead screw 12 for positioning a magnetic sensing head 14 on a magnetic disk 16, by providing s feedback signal which peaks about the center of the track regardless of whether or not the disk is being driven concentrically.

The tracks on a magnetic disk, such as tracks 0, 1 and 2 on disk 16 are commonly recorded with a series of data fields 18 on each track, with each data field being preceded by an ID or identification field or identifier 20, as is illustrated in Fig. 1. The present method and apparatus utilizes a disk 16 having the record identifiers 20 alternately displaced above and below their normal positions on the nominal center line 22 of at least one of the tracks on magnetic disk 16, as shown in Fig. 3. A central processing unit 24 is connected with magnetic head 14 and is arranged to count the total number of ID fields read by head 14 for each revolution of disk 16. A display, such as a meter 26, is connected with CPU 24 and gives a visual indication of the total number of ID fields 20 that are read per revolution of disk 16.

Fig. 3 illustrates the action of the head 14 when disk 16 is driven concentrically with the center 28 of a disk driving member, when the head 14 is located exactly over the center 22 of the track, and when the displacement width w is less than the acceptance width W. The displacement width w is the distance the identifiers 20 are displaced from the center line 22 of the track, and the acceptance width W is the largest distance that the head 14 may be displaced from the center line 22 and still maintain enough signal-to-noise ratio to be able to read the information correctly. If the displacement width w is close to...