Patent ID: 6290320
Filing Date: 2001-09-18
Classification: B41J,B43L,G01D,G06K

Abstract:
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.