Browse Prior Art Database

Digital Hyperbolic Function Speed Control

IP.com Disclosure Number: IPCOM000088989D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Bringol, CR: AUTHOR

Abstract

This article describes a digital circuit for generating a motor drive voltage in a magnetic disc drive that is hyperbolic in relation to the magnetic head position.

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Digital Hyperbolic Function Speed Control

This article describes a digital circuit for generating a motor drive voltage in a magnetic disc drive that is hyperbolic in relation to the magnetic head position.

The DC drive motor 1 engages the large drive wheel 2, as shown in the normal play and record modes. An emitter wheel 4 is connected to the leadscrew 5 which carries the magnetic head. A pair of optical sensors 3 are aligned on the emitter wheel 4. The emitter wheel 4 contains equal light and dark areas, and the sensors 3 are offset so that a gray code sequence is produced. The gray code sequence provides position information that can be decoded from the sensors 3 by decode 6.

The output of the decode 6 is used to update a leadscrew position counter 7. The leadscrew position counter 7 is initially set to the number of sectors starting at the center of the disc. The output of a function generator counter 8 is compared to the leadscrew position counter output by AND gate 9. The function generator counter is clocked by a CLK input which operates at a higher frequency rate than the input to the leadscrew position counter 7. When the outputs of the leadscrew position counter 7 and the function generator counter 8 are identical, a reset pulse is generated, resetting the function generator counter
8. The reset pulse also enables the pulse-width counter 10. The frequency screw position counter 7; thus, a hyperbolic function results.

The pulse-width counter 10 begins co...