Calibration technique for test patterns from multiple color inkjet printheads
AssigneeHewlett-Packard Company
InventorsRobert W. Beauchamp, Isidre Rosello Martos, Josep Tarradas
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Abstract
Light emitted from an obliquely angled LED source is directed by peripheral light tube walls which extend vertically toward media displaying printed indicia. The emitted light provides an illuminated area surrounding the printed indicia, while the light tube walls shield the printed indicia from excessive external light, so that a sensor measures the intensity of emitted light directly reflected from the media through a protective aperture.
Claims13
A method of sensing calibration test patterns made by multiple inkjet printheads of different colors mounted on a carriage comprising the following:
- applying a plurality of spaced apart bars to media to form a predetermined pixel pattern of a first resolution from each of the printheads, with adjacent bars for each different color printhead spaced a same distance apart and having a multiple pixel width;
- transmitting light from a carriage mounted light source at a non-perpendicular angular direction toward an area surrounding some of the bars;
- reflecting light from the area surrounding such some of the bars to a carriage-mounted photocell;
- passing a carriage-mounted optical sensor crosswise over such some of the bars to scan at a second resolution and measure a print contrast ratio in order to determine a relative position of such some of the bars, wherein such some of the bars are located in a central portion of the plurality of spaced apart bars.
Dependencies are inferred from the claim text.