Browse Prior Art Database

Tachometer Checking

IP.com Disclosure Number: IPCOM000087049D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Schaaf, RL: AUTHOR

Abstract

A two-phase tachometer T supplies A and B tachometer signals to a direction detector and decoder. The detector provides forward pulses F and reverse pulses R in response to the A and B forward and reverse tachometer signals. To ensure integrity of the tachometer system, the illustrated checking circuit responds to the rises and falls of the tachometer indicating signals A and B from the decoder, as labeled in forward waveforms for detecting symmetry drift errors, single phase dropout errors, phase misalignment and noise errors.

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Tachometer Checking

A two-phase tachometer T supplies A and B tachometer signals to a direction detector and decoder. The detector provides forward pulses F and reverse pulses R in response to the A and B forward and reverse tachometer signals. To ensure integrity of the tachometer system, the illustrated checking circuit responds to the rises and falls of the tachometer indicating signals A and B from the decoder, as labeled in forward waveforms for detecting symmetry drift errors, single phase dropout errors, phase misalignment and noise errors.

Gray code errors are continuously checked by AND circuit GC whereas the other errors are checked during motion of the tachometer by the phi A and phi B AND circuits. A rise in the A and B signals is memorized by the AL and BL latches, respectively. The detecting phi A and phi B AND circuits compare each memorized rise with an indicated fall. The latches are held reset during stop-lock (SL), i.e., when tachometer T is held in a supposedly stationary condition.

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