Browse Prior Art Database

Positioning System

IP.com Disclosure Number: IPCOM000097700D
Original Publication Date: 1961-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Hildebrand, JO: AUTHOR

Abstract

A servo network 11 provides fine positioning of an arm 12 radially with respect to a magnetic disk 17 having data tracks 7, a servo track 8 and a clock track 9. Arm 12 carries a plurality of data heads 13, a clock head 14 and a servo head 15. The latter senses the sectors 8a, 8b of servo track 8. The servo information is in the form of a checkerboard pattern having alternate magnetized and unmagnetized areas of a width corresponding to the data track spacing. Alternate even sectors 8a and odd sectors 8b are displaced from each other radially of the disk by an amount corresponding to one-half of the data track spacing. The selection of the odd or the even sectors is controlled by clock track 9.

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Positioning System

A servo network 11 provides fine positioning of an arm 12 radially with respect to a magnetic disk 17 having data tracks 7, a servo track 8 and a clock track 9. Arm 12 carries a plurality of data heads 13, a clock head 14 and a servo head 15. The latter senses the sectors 8a, 8b of servo track 8. The servo information is in the form of a checkerboard pattern having alternate magnetized and unmagnetized areas of a width corresponding to the data track spacing. Alternate even sectors 8a and odd sectors 8b are displaced from each other radially of the disk by an amount corresponding to one-half of the data track spacing. The selection of the odd or the even sectors is controlled by clock track
9.

The selected servo pattern is sensed by a pair of selectively connectable servo transducers 15a, 15b in head 15. Their center lines are displaced radially of the disk by an amount corresponding to one-quarter of the data track width. When the connected transducer is centered over the line formed by the abutting corners of intersections of the checkerboard squares, a voltage is induced in the transducer. It has one polarity as the transducer moves on to a matrix area and the opposite polarity when it moves off the matrix area, to produce a null. When the connected head is displaced from this line, the net voltage induced has a polarity and an amplitude indicating the direction and degree of displacement from the desired position.

This error voltage is supp...