Hewlett-Packard Development Company, L.p.

Roger Vinas

Francesc Subirada

Pau Soler

Francisco Javier Rodriguez

Carlos Millan

Pere Josep Canti

To compensate for color-calibration sensor drift, a measurement of bare-print-medium tonal value is taken in immediate time juxtaposition to each color test pattern; measured bare-medium tone is then used to correct color-patch readings. A line sensor or the like, on the scanning printhead carriage, is used for the reading. Preferably two such readings are taken, one at each end of each test pattern; ideally separate scans of the bare medium are taken without any test-pattern patch to develop longterm and short-term drift profiles, for refining the corrections. To compensate for calibration error due to runout in the carriage track&#x2014;particularly for wide-bed printers&#x2014;sensor response to bare medium is used to represent variations in carriage-to-medium spacing along the track; these variations are corrected in later sensor use.

Compensating for drift and sensor proximity in a scanning sensor, in color calibrating incremental printers

A system and method for providing thermal protection to printheads in a large format ink jet printer. In the system and method, an adaptive thermal print swath servo (&ldquo;ATPSS&rdquo;) module configured to divide a swath of a print operation into a plurality of individual cells is utilized. In a preferred embodiment, each cell is approximately four (4) inches long, although a user may configure the cell length for any length. The ATPSS module may be further configured to predict a peak temperature of each printhead in printing each cell of a swath. If any of the printheads is predicted to exceed a maximum allowed temperature (e.g., predetermined by the printhead manufacturer) in printing any of the cells, the ATPSS module may be further configured to divide an upcoming pass of the printhead across a recording medium into a series of sub-passes. In this respect, the upcoming pass is decomposed into a series of sub-passes by the utilizing a respective predetermined mask, which subsequently reduces a drop frequency (drops/time) proportionately to the number of sub-passes while maintaining the swath height. The predetermined mask divides the upcoming pass into an equivalent number of sub-passes without advancing the recording medium. Accordingly, the ATPSS module may preserve the life of the printheads by avoiding excessive heat generation in the printheads.

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Barcelona, Spain

Roger Vinas