Centronics Data Computer Corporation

Thomas T Butterfield

Prentice I Robinson

An opaque flag mounted upon a printer carriage assembly interrupts the light emmitted by a LED from reaching a phototransistor when at the left-hand margin of the paper document. The carriage starts to move and when it reaches constant print velocity, the opaque flag moves away from the LED and the phototransistor to activate the phototransistor to trigger a gated oscillator to generate pulses of very uniform size and shape and preferably of a 50% duty cycle. The leading and trailing edges of the pulses from the gated oscillator generate strobe and delay strobe pulses of shorter pulse duration which, in turn, energize the wire actuating solenoids forming full-step and half-step dots the full-step dots creating characters within a 5 .times. 7 dot matrix and both the half-stepand full-step dots being forming characters within a 9 .times. 7 dot matrix. When printing is completed, a PRIME signal resets and abruptly stops the gated oscillator. The carriage is returned to the left-hand margin doing so, moving the flag between the LED and the phototransistor to decouple the drive from the carriage assembly before reaching the left-margin and enable the carriage to coast to a stop. The sequence is repeated for each line of print.

Growing community of inventors

Chester, NH, United States of America

Thomas T Butterfield