Hewlett-packard Company

Hewlett-packard Development Company, L.p.

Thomas W Linder

Timothy L Weber

David J Waller

Linda C Uhlir-Tsang

John H Dion

A print command is received and a short, single, electrical precursor pulse is generated to preheat the ink components near the surface of the heating element. The precursor pulse returns precipitated ink components near the resistor to solution. For best results, the precursor pulse occurs approximately 1.50 microseconds prior to the main drive pulse even though other times, such as 1.00 microsecond, can produce adequate results. The main drive pulse then occurs to print the required information.

Precursor electrical pulses to improve inkjet decel

A printhead for an inkjet printer employs asymmetric orifices, such as an egg-shaped orifice, at the surface of the orifice plate to cause the ink drop tail to be severed at a predictable location from the orifice. The controlled tail and diminished spray of an ink droplet expelled from the asymmetric orifice results in improved edge roughness and improved quality of print.

Asymmetric printhead orifice

In order to optimize print quality, it is desirable to minimize the distance between a inkjet printhead and the media that is being printed on. This reduces print quality degradation by stray drops of ink with different trajectories than the main drop and errors in the nominal trajectory of the main drop. Color inkjet printers commonly employ a plurality of print cartridges, usually either two or four, mounted in the printer carriage to produce a full spectrum of colors. In a multiple printhead printer, it is advantageous if the black print cartridge is closer to the print media when printing text than is the color cartridge when printing color graphics. The apparatus and method of this disclosure enables the black printhead in an inkjet printer with both black and color cartridges to be as close to the media as possible so that black text print quality will be optimized while also allowing the printing of color graphics. Since black text print quality is more sensitive to printhead-to-media distance than is color graphics quality, the overall print quality of both black text and color graphics is optimized.

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Corvallis, OR, United States of America

Thomas W Linder