Hewlett-Packard Company

Kai K Lu

Ronald Albert Askeland

Mark L Choy

Gary W Byers

The center-to-center spacing of pens containing a 'problematic' combination of inks is increased to introduce a relatively small additional time-delay in which those particular constituents are applied to the same or adjacent areas during a single pass, thereby providing a substantial improvement in print qualities (such as Halo or Bleed) on plain (untreated) and special purpose (matt, glossy, transparent) print media, without substantially increasing the throughput rate. The center-to-center spacing of a critical combination of pens is substantially greater than the width of a single pen, thereby providing an increased delay that is equal to the increased spacing divided by the traverse speed. Different delays are provided for different combinations of ink by arranging at least three pens in a fixed sequence with different fixed spacings between different combinations of pens, such that a greater spacing and thus a longer delay is associated with one or more combinations of inks which interact adversely on print quality, and a shorter delay with at least one combination of inks which interacts less adversely on print quality. In particular, if a particular pair of two pens is a 'problematic' combination requiring a longer delay and other pairs are 'safe' combinations requiring a shorter delay, the pair requiring the longer delay may be held in two non-adjacent compartments, possibly separated by one or more other pens. In one particular example, the order is KMCY, which provides an effective center-to-center spacing of 2 pen widths for the two 'problematic' combinations of KC and YM, and a center-to-center spacing of at least 1 pen width for the four safe combinations, thereby providing an economic solution to improve print qualities such as Halo and Bleed by increasing the center-to-center spacing of the pens associated with one or more 'problematic' combinations of inks, without any noticeable change in throughput rate.

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San Diego, CA, United States of America

Kai K Lu