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Reel To Reel Web Motion Control

IP.com Disclosure Number: IPCOM000084195D
Original Publication Date: 1975-Oct-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 58K

Publishing Venue

IBM

Related People

Hendee, RC: AUTHOR

Abstract

Substantially constant velocity web motion can be achieved in reel-to-reel transfer, when stepper motors are used at both the supply and take-up reels. Motor advance pulses are applied to the driving or take-up motor as a function of the pulse rate sensed at the driven or supply motor. Periodic pulse ratio sampling provides adequate control.

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Reel To Reel Web Motion Control

Substantially constant velocity web motion can be achieved in reel-to-reel transfer, when stepper motors are used at both the supply and take-up reels. Motor advance pulses are applied to the driving or take-up motor as a function of the pulse rate sensed at the driven or supply motor. Periodic pulse ratio sampling provides adequate control.

In the figure, either the left or right motor can be the driving motor at the take- up reel, with the other serving as the driven transducer at the supply reel. Assuming the left motor is driving, its ON condition is indicated at latch 1 which conditions AND's 2 and 3. The left motor then receives motor advance pulses at an initial preset rate which is sampled at analog-digital (AD) converter 4, and resulting pulses increment binary counter I through AND 3 and OR 5.

The advancement of the left motor causes the right motor, as it is rotated, to generate output pulses at some rate dependent on the ratio of radii. These pulses cause AD converter 6 to supply pulses to AND's 2 and 7, both of which are presently blocked because of the absence of a signal from trigger 24.

Drive pulses continue to increment Counter I and at a count of two, AND 8 supplies a reset signal to latches 14-18. Latches 14-16 turn on a respective oscillator 19, 20 or 21, each of which provides a characteristic output pulse frequency for driving a stepper motor. During start-up, there is a circuit, not shown, which continues to activate oscillator 19 to continue the advancement of the driving motor and pulses for counter I.

When counter I reaches a count of three at the next pulse, AND 22 provides a gating signal at AND's 9, 10, 11, 12, and 13. These conditioned ANDs gate one of the lines from the decoder to thereby set one of the latches 14-18. Since counter II was blocked, during the start-up period, no count latch is activated and oscillator 19 will continue to provide drive pulses. At a count of four, AND 23 provides a reset pulse for counter II.

Counter I continues its advance and at a count of 16 sets trigger 24 which blocks AND's 8, 22, and 23 and conditions AND's 2 and 25. Pulses now received from the driven motor through converter 6 are effective to increment counter II through AND 2 and OR 26. During this time, counter I is progressing through another count cycle from motor advance pulses from converter 4. Control pulses at counts two, three and four are blocked during thi...