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More Accurate Position Indication for Stepper Motor Drives

IP.com Disclosure Number: IPCOM000048211D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Bahr, DJ: AUTHOR [+2]

Abstract

The illustrated arrangement permits high resolution position indication for mechanical components actuated by stepper motors. Position indication is effected by logically combining a position indication pulse from a moving mechanical component with a selected stepper motor incrementation pulse. Thus, the accuracy of the position indication is solely dependent upon the accuracy of the stepper motor and the mechanical component it actuates.

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More Accurate Position Indication for Stepper Motor Drives

The illustrated arrangement permits high resolution position indication for mechanical components actuated by stepper motors. Position indication is effected by logically combining a position indication pulse from a moving mechanical component with a selected stepper motor incrementation pulse. Thus, the accuracy of the position indication is solely dependent upon the accuracy of the stepper motor and the mechanical component it actuates.

The illustrated example is based on a two-phase stepper motor 1 to which incrementation pluses from a motor control circuit 6 are applied via control lines 2 to 5. The incrementation pulses are associated with motor incrementation phases A, B, A and B, so that pulse A occurs on line 2, pulse A on line 3, pulse B on line 4, and pulse B on line 5. These pulses occur in a known manner in four different combinations; i.e., a phase combination reoccurs every four steps. An actuator element 9 is driven by motor shaft 7 through gear 8. A mirror 10, scanned by photoelectric scanner 14, is fixed to actuator element 9. For this purpose, scanner 14 is provided with a light-emitting diode 11 and a phototransistor 12 which are both positioned in such a manner that the light emitted by diode 11 when passing mirror 10 is reflected. As a result, phototransistor 12 is irradiated, emitting an output pulse to AND circuit 13. Further inputs of AND circuit 13 are connected to lines 3 and 5,...