Printer system

Abstract

A dot matrix printer system utilizes a reciprocating shuttle having a plurality of hammer elements and externally energized hammer controls mounted with the hammers on the shuttle. Each hammer scans a number of dot printing positions within a dot matrix line, and is energized at a high repetition rate during movement to imprint serially the dot patterns in that line for several successive characters. The paper is then advanced and the next dot matrix line is printed in the reverse direction. The shuttle mechanism forms a part of a dynamically balanced system, being in one example driven in a trapezoidal motion from a cam system that also engages an oppositely moving counterweight system. A highly reliable fast acting hammer bank comprises an array of individual spring hammer elements and associated magnetic actuators, the hammer elements normally being magnetically biased to a retract position by a permanent magnet. The magnetic field is neutralized to permit hammer flight with controlled velocity for imprinting, with hammer return being automatically achieved by the magnetic bias. The system is amenable to generation of a wide variety of dot matrices and arbitrary printing patterns, and provides uniform and well defined characters through a substantial number of copies, but nevertheless operates reliably and at high speed with a low cost mechanism that does not require adjustment.