Test pattern implementation for ink-jet printhead alignment
AssigneeHewlett-Packard Company
InventorsDan Arquilevich, John A Underwood, Braulio Soto, Charles Woodruff
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Abstract
A method and means for automatic alignment of ink-jet printheads includes fitting measuring constructs to actual print data acquired form a print made using a given, predetermined, test pattern data set. Specific test patterns for use in automated alignment of ink-jet printheads are suited to providing a variety of printhead alignment information in a compact format. The test pattern data set incorporates techniques for avoiding carriage-induced dynamic errors during automated alignment of ink-jet printheads.
Claims17
A method for aligning ink-jet pens in a hard copy apparatus having a scanning carriage with a plurality of said ink-jet pens mounted therein, each of said pens having a printhead, each of said printheads having a plurality of ink drop firing nozzles, said pens being controlled by a printhead ink-jet nozzle-firing algorithm, said method comprising:
- printing a test pattern on a single sheet of print media, said test pattern including repetitious pairs of colored test objects wherein said pairs of colored test objects are respectively related to a plurality of error correction values for aligning said printheads such that in combination said values are defined for said algorithm;
- optically measuring actual offsets between the objects of each pair wherein offsets are indicative of respective printhead alignment aspects, including x-axis, y-axis, and z-axis alignments;
- calculating at least one printhead alignment error correction factor from said actual offsets;
- and
- providing a printhead alignment error correction factor to said nozzle-firing algorithm.
A computer memory for calculating factors for aligning ink-jet pens in a hard copy apparatus having a scanning carriage with a plurality of ink-jet pens mounted therein, each of said pens having a printhead, each of said printheads having a plurality of ink drop firing nozzles, and said apparatus including a printhead ink-jet nozzle-firing algorithm, comprising:
- computer code for printing a test pattern on a single sheet of print media, said test pattern including repetitious pairs of colored test objects wherein said pairs of colored test objects are respectively related to a plurality of error correction values for aligning said printheads such that in combination said values are defined for said algorithm;
- computer code for storing optically measured actual offsets between the objects of each pair wherein offsets are indicative of respective printhead alignment aspects, including x-axis, y-axis, and z-axis, alignments;
- and
- computer code for calculating at least one printhead alignment error correction factor from said actual offsets.
A method for correcting firing trajectories of a plurality of ink-jet pens mounted in a hard copy apparatus scanning carriage, each of said pens having a printhead, each of said printheads having a plurality of ink drop firing nozzles, wherein each printhead is controlled by an ink-jet nozzle-firing algorithm, said method comprising:
- printing a test pattern on predetermined regions of a single sheet of A-size print media, said test pattern including repetitious pairs of colored test objects wherein said pairs of colored test objects are respectively related to a plurality of error correction values for aligning said printheads such that in combination said values are defined for said algorithm, including printing a first region for acquiring reflectance value data indicative of x-axis error correction values, printing a second region for acquiring reflectance value data indicative of y-axis error correction values, printing a third region for acquiring reflectance value data indicative of error correction values in column-to-column spacing nozzle sets firing a same color ink from different nozzle columns of an individual printhead, printing a fourth region for acquiring reflectance value data indicative of primitive-by-primitive error correction values, and printing a fifth region for acquiring reflectance value data indicative of bidirectional, variable speed printing x-axis error correction values;
- optically measuring actual offsets between the objects of each pair wherein offsets are indicative of respective printhead alignment aspects;
- calculating at least one printhead alignment error correction factor from said actual offsets;
- and
- providing said at least one printhead alignment error correction factor to said nozzle-firing algorithm.
Dependencies are inferred from the claim text.