Browse Prior Art Database

Magnetic Tape Unit Reel Motor Servomechanism

IP.com Disclosure Number: IPCOM000075867D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Frauenfelder, LS: AUTHOR

Abstract

This motor servomechanism controls the file reel motor and machine reel motor of a magnetic tape unit, having vacuum column tape buffers 1 and 2, in accordance with the position of tape loops 3 and 4 as sensed by a capacitance sensor associated with each column. The capacitor sensors, not shown, are of the type shown in U. S. Patent 3,122,332.

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Magnetic Tape Unit Reel Motor Servomechanism

This motor servomechanism controls the file reel motor and machine reel motor of a magnetic tape unit, having vacuum column tape buffers 1 and 2, in accordance with the position of tape loops 3 and 4 as sensed by a capacitance sensor associated with each column. The capacitor sensors, not shown, are of the type shown in U. S. Patent 3,122,332.

The servomechanism for the machine reel motor 11 is shown in View B. The file reel motor servomechanism is of the same type. Capacitance loop sensor 5 provides two in-phase and oppositely variable magnitude AC signals and 7 whose magnitudes are oppositely proportional to the position of tape loop 4 relative to a reference midposition in column 2. These AC signals are demodulated by demodulator 8 to produce a variable-magnitude reversible- polarity DC signal VAB. This DC signal is applied through lead networks as an input to differential amplifier 9 whose output controls linear power amplifier 10. The output of the power amplifier is connected to reversibly energize DC machine reel motor 11.

The direction of tape movement, either forward (FWD) or backward (BKWD), is determined by the direction of rotation of capstan 12. A pair of capacitor bridges 13 and 14 are controlled in accordance with the direction of capstan rotation by the voltage on conductors 15 and 16. This voltage is shown in the table of View C for the various modes of operation of the tape unit. The output voltages o...