Thomas S Butterfield

US Patent:

40761118, Feb 28, 1978

Filed:

Jul 8, 1976

Appl. No.:

5/703623

Inventors:

Prentice I. Robinson - Pelham NH
Thomas T. Butterfield - Chester NH

Assignee:

Centronics Data Computer Corporation - Hudson NH

International Classification:

B41J 304

US Classification:

197 1R

Abstract:

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.