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Browse Prior Art Database

Magnetic Drum Speed Control

IP.com Disclosure Number: IPCOM000098575D
Original Publication Date: 1959-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Carter, DL: AUTHOR

Abstract

Often it is desired to control the rotational speed of a magnetic drum. The electrical block diagram illustrates a method for performing that function. The drum is driven by an air turbine having a valve for controlling its speed. The valve is designed to have two speed settings represented by a low speed stop and a high speed stop. A magnetic timing track is placed on the drum to cooperate with a magnetic head so as to derive electrical pulses having a frequency determined by, the rotational speed of the drum. These electrical pulses are then amplified and converted into a sign wave for application to a frequency discriminator which produces either a plus or minus control voltage. This depends on whether the frequency of the electrical pulses is greater or smaller than its center frequency.

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Magnetic Drum Speed Control

Often it is desired to control the rotational speed of a magnetic drum. The electrical block diagram illustrates a method for performing that function. The drum is driven by an air turbine having a valve for controlling its speed. The valve is designed to have two speed settings represented by a low speed stop and a high speed stop. A magnetic timing track is placed on the drum to cooperate with a magnetic head so as to derive electrical pulses having a frequency determined by, the rotational speed of the drum. These electrical pulses are then amplified and converted into a sign wave for application to a frequency discriminator which produces either a plus or minus control voltage. This depends on whether the frequency of the electrical pulses is greater or smaller than its center frequency.

These plus or minus control voltages are then used to control the direction of rotation of a DC motor which operates through a bi-directional slip clutch to rotate the valve to either the low speed or high speed stop. When the frequency of the pulses detected by the magnetic head is below the center frequency of the frequency discriminator, the DC motor is rotated so that the valve is driven to the high speed stop. On the other hand, when the frequency of the electrical pulses detected by the magnetic head is above the center frequency of the frequency discriminator, the DC motor is energized so that the valve is rotated to its low speed stop. If t...