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Browse Prior Art Database

Tape Speed Control Method

IP.com Disclosure Number: IPCOM000080118D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Thorpe, AC: AUTHOR

Abstract

Fig. 1 illustrates a direct reel-to-reel tape drive employing no tape drive capstan. The reels are driven by shafts A and B, which are driven in turn by any suitable mechanism powered by a DC motor, not illustrated in Fig. 1. Fig. 2 indicates the circuitry and method for controlling the speed V of the tape in either direction. As illustrated in Fig. 2, the emitter wheels E are mounted on shafts A and B for rotation therewith and are rotated at the same speed as the reels. Each emitter wheel creates a train of pulses picked up by the sensors S at regular angular intervals. The sensors may be magnetic, optical, or mechanical and serve to pick up the leading and trailing edge of each notch or tooth in the emitter wheels.

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Tape Speed Control Method

Fig. 1 illustrates a direct reel-to-reel tape drive employing no tape drive capstan. The reels are driven by shafts A and B, which are driven in turn by any suitable mechanism powered by a DC motor, not illustrated in Fig. 1. Fig. 2 indicates the circuitry and method for controlling the speed V of the tape in either direction. As illustrated in Fig. 2, the emitter wheels E are mounted on shafts A and B for rotation therewith and are rotated at the same speed as the reels. Each emitter wheel creates a train of pulses picked up by the sensors S at regular angular intervals. The sensors may be magnetic, optical, or mechanical and serve to pick up the leading and trailing edge of each notch or tooth in the emitter wheels. Assuming that:
TA equals the width of a pulse from the emitter wheel E on shaft A;

TB equals the width of a pulse from the emitter wheel E on shaft B; rA equals the radius of tape reel A; rB equals the radius of tape reel B;

V equals the tape velocity (which is constant);

WA is the angular velocity of shaft A;

WB is the angular velocity of shaft B; fA equals the frequency of the emitter pulses from shaft A; and fB equals the frequency of emitter pulses from shaft B;

(Image Omitted)

While this would be adequate for use on most types of tape velocity controls, a better speed control may be desired and this may be achieved by utilizing the expression (TA + TB) - K1n(TA + TB) in substitution for simply (TA + TB) as the feedback control. Constant K may be solved...