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Logic for Tracking the Location of a Print Head

IP.com Disclosure Number: IPCOM000078391D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Clarkson, RD: AUTHOR [+2]

Abstract

This logic interprets pulse sequences to reflect direction of motion and distance. The circuit is particularly useful for tracking the number of print positions a print head has moved with the position information not being lost, even after several reversals of direction or stops or both.

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Logic for Tracking the Location of a Print Head

This logic interprets pulse sequences to reflect direction of motion and distance. The circuit is particularly useful for tracking the number of print positions a print head has moved with the position information not being lost, even after several reversals of direction or stops or both.

The input to the circuit is three sequences of pulses A, B and C shown in Fig. 1 such as might be produced by an emitter that is position-sensitive and does not depend on the velocity of motion. The emitter is mounted on the print head whose motion is to be tracked.

The circuit of Fig. 2 transforms the input signals into binary outputs from an up-down counter. The output of this counter indicates what print position the print head is on or less than one print position away from. The signal first passes through a latch single-shot arrangement which prevents the up-down counter from oscillating due to noise. If an input to one of the channels A, B or C fires a single-shot for that channel, then that channel is latched up and will not fire again until one of the other two channels is latched up. Thus, if the Print head were to vibrate over a print position causing the emitter to send a series of pulses to one channel, the single-shot for that channel would fire only once. Once the single- shot for either channel A, B or C has fired, the output from the single-shot is used in two ways. The leading edge of the single-shot pulse is used...