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Single Control Drive Circuit for Plurality of Stepper Motors

IP.com Disclosure Number: IPCOM000043789D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Dingle, WA: AUTHOR

Abstract

Each of a plurality of stepper motors (three shown at M1, M2, and Mn) is selectively activated in a desired direction from a motor selector, which receives signals from a computer 11 and a control module (CM) 12 in accordance with when each of the motors is to be energized and its direction of rotation when energized. A power control 13 supplies the required current through selected windings of the selected stepper motor to rotate the motor in the desired direction, and the current level of the motor winding is sensed by monitoring a voltage at points 1, 2, and n for the motors M1, M2, and Mn, respectively, with these voltages being supplied as inputs to the control module 12. As shown in Fig. 2a, the control module 12 receives an A signal from the computer 11 (Fig. 1) for controlling PNP transistors 14 (Fig.

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Single Control Drive Circuit for Plurality of Stepper Motors

Each of a plurality of stepper motors (three shown at M1, M2, and Mn) is selectively activated in a desired direction from a motor selector, which receives signals from a computer 11 and a control module (CM) 12 in accordance with when each of the motors is to be energized and its direction of rotation when energized. A power control 13 supplies the required current through selected windings of the selected stepper motor to rotate the motor in the desired direction, and the current level of the motor winding is sensed by monitoring a voltage at points 1, 2, and n for the motors M1, M2, and Mn, respectively, with these voltages being supplied as inputs to the control module 12. As shown in Fig. 2a, the control module 12 receives an A signal from the computer 11 (Fig. 1) for controlling PNP transistors 14 (Fig. 2b) and 15 of the power control 13 (Fig.
1). When the A signal is high, one of the two transistors 14 (Fig. 2b) and 15 is turned on in a PWM (pulse-width modulation) mode on while the other is turned on when the A signal is low. The state of a B signal from the computer 11 (Fig. 1) to the control module 12 controls whether an NPN1 (Fig. 2a) or NPN 2 signal is high. The NPN1 signal is supplied to each of three gates 16 of an integrated circuit 17, which is a TTL 7407. The NPN2 signal is supplied to each of three gates 18 of the integrated circuit 17. The integrated circuit 17 and an integrated circuit 19, which is a TTL 7406, comprise the motor selector 10 of Fig. 1. The number of the gates 16 (Fig. 2a) and the number of the gates 18 are the same and equal to the number of motors to be controlled. The integrated circuit 19 includes a plurality of inverters 20. Each of the inverters 20 of the integrated circuit 19 has a high output when its input is low. Only one pair of the inverters 20 can have a high output at any time. The number of pairs of the inverters 20 is the same as the number of motors. Only one of the motors can be energized at any time with this requiring high outputs from the inverter 20 and one of the gates 16 or 18 connected to the output of the same inverter 20. An NPN transistor 21 has its base connected to one of the inverters 20 and one of the gates 16 and is turned on when the outputs of the gate 16 and the inverter 20 are high. An NPN transistor 22 has its base connected to one of the gates 18 and one of the inverters 20 and is turned on when the outputs of the gate 18 and the inverter 20 are high. The outputs of the gates 16 and 18 can never be high simultaneously because only one of the NPN1 and NPN2 signals can be high at any time. The transistor 21 has its collector connected to windings 23 and 23' of the motor M1, and the transistor 22 has its collector connected to windings 24 and 24' of the motor M1. As shown in Fig. 3, the A signal to the control module 12 leads the B signal. When the A signal is high, the PNP1 signal is high. When the A...