Browse Prior Art Database

Disk Drive Motor Speed Control

IP.com Disclosure Number: IPCOM000052074D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Bellamy, LR: AUTHOR [+2]

Abstract

Digital control techniques are employed to control the speed of a motor driving a magnetic disk file. Disk motor speed control was formerly achieved by microprocessor algorithms which corrected the motor phase table depending on the history of former early or late sector marks recorded on the disk. The present technique achieves a 5 times improvement in speed accuracy by the use of a digital control method.

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Disk Drive Motor Speed Control

Digital control techniques are employed to control the speed of a motor driving a magnetic disk file. Disk motor speed control was formerly achieved by microprocessor algorithms which corrected the motor phase table depending on the history of former early or late sector marks recorded on the disk. The present technique achieves a 5 times improvement in speed accuracy by the use of a digital control method.

In this method, the power drivers of the motor windings are driven from logic signals supplied from an eight-bit shift register which is caused to shift the phase data on the occurrence of every fourth late sector mark. In addition, the power drivers are gated off whenever the sector marks are early, so that the motor rotor is essentially coasting.

The motor used in this technique is a 2-phase hysteresis synchronous type. The time sequence of the phase data is shown in the bottom figure, together with the shift register data.

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