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Asynchronous Direction of Motion Detection

IP.com Disclosure Number: IPCOM000077103D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Crisp, JM: AUTHOR

Abstract

This digital logic network asynchronously derives direction-of-motion information from the two 90 degrees displaced output signals of 2-phase digital tachometer 1. The tachometer is driven by clockwise (CW) or counter-clockwise (CCW) rotation of motor 2.

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Asynchronous Direction of Motion Detection

This digital logic network asynchronously derives direction-of-motion information from the two 90 degrees displaced output signals of 2-phase digital tachometer 1. The tachometer is driven by clockwise (CW) or counter-clockwise (CCW) rotation of motor 2.

The two possible tachometer output signal patterns, phase A on conductor 3 and phase B on conductor 4, are shown in Figs. 2 and 3. For CW rotation, the state sequence is AB, AB, AB, AB. For CCW rotation, the state sequence is AB, AB, AB, AB.

When the motor is rotating CCW, latch 5 (Fig. 4) is set and an active output is provided on conductor 6. This latch is set by either of the following two conditions: the AB state, followed by the AB state, with A delayed; or the AB state followed by the :AB state, with A delayed.

The AB state is sensed by AND 7. The output of this AND resets latch 8, providing an active output on conductor 9. The following AB state provides an active input to AND 10 on conductor 11, and provides a delayed active input on conductor 12, as delayed by exclusive OR 13. AND 10 is thus enabled and latch 5 is set.

The next state, AB, provides an active output from exclusive OR 19 to hold latch 5. This same AB state is sensed by AND 14a. The output of this AND sets latch 8, providing an active output on conductor 14. The following AB state provides an active input to AND 15 on conductor 16, and provides a delayed active input on conductor 17, as delayed by e...