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Regulated Speed Ribbon Drive

IP.com Disclosure Number: IPCOM000051940D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 4 page(s) / 118K

Publishing Venue

IBM

Related People

Davis, GW: AUTHOR [+3]

Abstract

In a dual-motor drive system for ink ribbons of a printer one motor drags while the other is driven. In this system the stepping rate of the drive motor is periodically adjusted as the take-up reel diameter increases to allow more torque while maintaining the reserve torque almost constant. Basically, the drive system works by sensing the drag motor velocity which is directly proportional to the take-up reel diameter and using this parameter to regulate the stepping rate of the drive motor.

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Regulated Speed Ribbon Drive

In a dual-motor drive system for ink ribbons of a printer one motor drags while the other is driven. In this system the stepping rate of the drive motor is periodically adjusted as the take-up reel diameter increases to allow more torque while maintaining the reserve torque almost constant. Basically, the drive system works by sensing the drag motor velocity which is directly proportional to the take-up reel diameter and using this parameter to regulate the stepping rate of the drive motor.

The system operates in accordance with the following sequence:

1. The drive motor is started at a predetermined stepping

rate for a fixed period of time.

2. During that time the drag motor velocity is measured

and translated into a correction factor for modifying

the drive motor stepping rate up or down.

3. Adjust the drive motor speed to gradually assume the

new stepping rate.

4. Repeat the steps of paragraphs 2 and 3 continuously in

accordance with the correlation graph shown in Fig. 2.

Referring to Fig. 1, drag motor velocity is shown as a pulse rate at the output of velocity sense detector 10. This frequency is converted to a DC voltage by the frequency-to-voltage converter 11. Capacitor 13 is charged to a fixed voltage level by step generator 12 which applies voltage pulses at the rate of 180 per second which is the arbitrary number of steps at which the drive motor is started. After single-shot 14 times out, generator 12 will float, allowing capacitor 13 to gradually assume a new DC voltage representing the actual ribbon velocity as produced by velocity sense circuitry 10 and the frequency-to-voltage converter
11. The voltage appearing on capacitor 13 is inverted and converted to a frequency by blocks 15 and 16 for application to the stepper motor.

An alternate approach to achieve the same regulation is shown in Figs. 3-5. Microprocessor MPU1 starts issuing motor advance pulses at a selected rate, e.g., 180 steps/sec via programmed timer (PTM) 2/1. After a suitable delay to allow the ribbon drive to come up to speed and to stabilize, N samples of the feedback pulse duration are taken usi...