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# Circuitry for Conserving Power in Stepping Motors

IP.com Disclosure Number: IPCOM000082687D
Original Publication Date: 1975-Jan-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 34K

IBM

## Related People

Herald, RF: AUTHOR [+2]

## Abstract

The circuitry functions to maintain only one winding C or D energized of a two-phase four-winding stepping motor having the windings A, B, C and D, for thereby holding the output shaft 22 of the motor stationary when motor 20 is inoperative to drive its load. Only the power for holding one winding energized is thus required for this state of the stepping motor.

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Circuitry for Conserving Power in Stepping Motors

The circuitry functions to maintain only one winding C or D energized of a two-phase four-winding stepping motor having the windings A, B, C and D, for thereby holding the output shaft 22 of the motor stationary when motor 20 is inoperative to drive its load. Only the power for holding one winding energized is thus required for this state of the stepping motor.

The circuitry also includes an AC motor 24, the operation of which is controlled by a relay 26. AC motor 24 may be used for driving one portion of a document card machine, while stepping motor 20 may drive another portion of the machine. Relay 26 is controlled by a logic level voltage line "-AC motor run". AC motor 24 must, by definition, be energized and up to speed before stepping motor 20 can be stepped. Likewise, AC motor 24 will always remain running after the last step of stepping motor 20.

The sequence of the start operation for stepping motor 20 is as follows: 1. At the rest condition of motor 20, lines "+phase A" and "+phase B" can each be either at an up or a down level. For the rest condition, the line -AC motor run is at an up level. This signal level of the -AC motor run line disables both of the AND circuits 3 and 4, so that neither the winding A nor the winding B of motor 20 can be energized at this time. Under these conditions, either winding C or winding D can be energized, depending on the signal level of the +phase B line. Shaft 22 is held stationary by energization of the single winding C or D. 2. The line -AC motor run moves to a down level so as to start AC motor 24 by relay 26. At this time, the logical conditions for either AND circuit 3 or 4 are met depending upon the signal level of the +phase A line. If the signal level on +phase A line is high, AIM circuit 4 is enabled causing driver 8 to energize winding B of motor 2O. If the +phase A signal is down, AND circuit 3 causes driver 7 to energize winding A in lieu of winding B. Under either of these conditions, the shaft 22 of stepping motor 20 moves a half step. The half step is just half of a step of the shaft 22 during running conditions of motor 20, in which different pairs of the windings A, B, C and D are energized sequentially to cause steps of the shaft 22. Because sufficient time is allowed for the AC motor 24 to come up to speed, stepping motor 20 can take its half step and settle out before the following sequence 3. 3. Stepping motor lines +phase A and +phase B are now toggled (for each toggling operation, the signal level on one line is allowed to remain the same at the same time as the signal level on the other line is changed), in order to...