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Browse Prior Art Database

Measuring and Adjusting Speed of Magnetic Disk Access Arm

IP.com Disclosure Number: IPCOM000087171D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Brownback, DE: AUTHOR [+2]

Abstract

This mechanism measures the speed of an access arm 10 carrying a magnetic transducer 12 over a magnetic disk 14 utilizing two light-emitting diodes (LEDs) 16 and 18 as indicators. It includes a potentiometer 20 for adjusting the reference level of a digital-to-analog converter (DAC) 22 for adjusting the speed of arm 10 within a desired range.

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Measuring and Adjusting Speed of Magnetic Disk Access Arm

This mechanism measures the speed of an access arm 10 carrying a magnetic transducer 12 over a magnetic disk 14 utilizing two light-emitting diodes (LEDs) 16 and 18 as indicators. It includes a potentiometer 20 for adjusting the reference level of a digital-to-analog converter (DAC) 22 for adjusting the speed of arm 10 within a desired range.

A central processing unit 24 enters the desired number of tracks on disk 14 to be accessed into down counter 26. Down counter 26 drives read-only memory (ROM) 28 which in turn drives DAC 22 so as to provide a desired velocity signal on its output 30, shown in Fig. 2 as a curve including a rising portion W, a horizontal flat portion X and a descending portion Y. The ROM 28 is preprogrammed in connection with the DAC 22 so as to provide this curve on the DAC output 30. The control signal shown in Fig. 2 is applied through operational amplifier 32 on comparator 34. Measuring logic 36 actuated by movement of access arm 10 applies an actual arm velocity signal through line 38 on comparator 34, and comparator 34 thus acts on actuator 40 to move arm 10 and transducer 12 with the velocities shown in Fig. 2. Down counter 26 is effective on ROM 28 so that ROM provides its preprogrammed output to DAC 22, in accordance with the position of transducer 12 on disk 14 by the application of track-crossing pulses on line 42 derived from measuring logic 36 and applied to down counter 26.

The speed of transducer 12 is measured particularly when transducer 12 passes from the 64th track on disk 14 to the 63rd track...