Lexmark International, Inc.

David Steven Waldrop

George Keith Parish

Randall David Mayo

Robert Wilson Cornell

John Philip Bolash

Thomas Jon Eade

Lawrence Russell Steward

Curt Paul Breswick

David Keith Lane

An ink jet printing apparatus includes a printhead controller including a printhead driver circuit having a set of ink jet nozzle control outputs and a printhead select circuit having a plurality of printhead select outputs. A plurality of printheads are provided, wherein each printhead includes a plurality of ink jet nozzles, a plurality of individually controllable ink jet nozzle firing circuits, and a printhead enable circuit, wherein the printhead enable circuit is electrically coupled between the plurality of individually controllable ink jet nozzle firing circuits and the set of ink jet nozzle control outputs, and wherein the printhead enable circuit is electrically coupled to one of the plurality of printhead select outputs and enables the electrical conduction of the plurality of controllable ink jet nozzle firing circuits upon receipt of a printhead select signal from one of the printhead select outputs of the printhead select circuits.

Apparatus for driving multiple ink jet printheads with a single set of

A print quality enhancement arrangement for a dot matrix printer such as a thermal ink jet printer. The arrangement includes a buffer for receiving 300 dots per inch (dpi) resolution data in the horizontal (print head movement) direction and creates 600 dpi resolution data using image enhancement techniques. The arrangement further includes correction of the higher resolution data to remove pels which are unprintable due to the frequency response of the print elements in the print head. The correction is performed using knowledge of the history of printed pels and the original 300 dpi data. The creation of the higher resolution data and its correction occur 'on-the-fly' as data is being fed to the print head, rather than through the creation of a 300 by 600 dpi bitmap.

Print quality enhancement method and apparatus

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Lexington, KY, United States of America

David Steven Waldrop