Patent ID: 6604808
Filing Date: 2003-08-12
Classification: B41J

Abstract:
A method for determining the skew of a printhead of a printer, wherein the method comprises the steps of:a) printing first, second and third spaced-apart images at least partially aligned substantially along the printhead scan direction, wherein the first and third images are printed by one of an upper portion and a lower portion of the printhead, and wherein the second image is printed by the other of the upper portion and the lower portion of the printhead between the first and third images so that in the absence of printhead skew the center of the second image is equidistant along the printhead scan direction from the centers of the first and third images; b) moving a sensor at a velocity in the printhead scan direction over the first, second and third images; c) obtaining temporally sampled data points from the sensor for the entire sensor movement of step b), wherein each sampled data point indicates the presence or absence of an image; d) storing all of the sampled data points in a memory, wherein the memory contains all of the sampled data points at the same time; e) calculating using the stored sampled data points the first, second and third centers of the respective first, second and third images; and f) calculating a function of the first, second and third centers, wherein the calculated function indicates the skew of the printhead.