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US 6,604,808 B2Granted
Method for determining the skew of a printhead of a printer
AssigneeLexmark International, Inc.
InventorsDavid Golman King, Patrick Laurence Kroger, Randall David Mayo
Life of this patent
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Abstract
A method for determining the skew of a printhead of a printer. At least three images are printed which are at least partially aligned substantially along the printhead scan direction with the middle image printed from one of the upper and lower portions of the printhead and with the adjacent images printed from the other of the upper and lower portions of the printhead. A sensor is moved in the printhead scan direction over the images. A function is calculated from the sensor output, wherein the calculated function indicates the skew of the printhead.
Claims28
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.
4 more elements
A method for determining the skew of a printhead of a printer, wherein the method comprises the steps of:
- a) printing a first plurality of spaced-apart images and a second plurality of spaced-apart images, wherein the images of the first and second pluralities are at least partially aligned substantially along the printhead scan direction, wherein the images of the second plurality are spaced apart from and interleaved with the images of the first plurality, wherein the images of the first plurality are printed by one of an upper portion and a lower portion of the printhead, and wherein the images of the second plurality are printed by the other of the upper portion and the lower portion of the printhead so that in the absence of printhead skew the center of each image of the second plurality is equidistant along the printhead scan direction from the centers of the adjacent images of the first plurality;
- b) moving a sensor at a velocity in the printhead scan direction over the images of the first and second pluralities;
- 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 centers of the images of the first and second pluralities;
- and
- f) calculating a function of the centers of the images of the first and second pluralities, wherein the calculated function indicates the skew of the printhead.
4 more elements
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 distance from the second image to the first image is equal to the distance from the second image to the third image;
- b) moving a sensor in the printhead scan direction over the first, second and third images;
- and
- c) calculating a function of the output of the sensor, wherein the calculated function indicates the skew of the printhead,
- wherein the first, second and third images are sized to each completely fill the field of view of the sensor.
2 more elements
A method for determining the skew of a printhead of a printer, wherein the method comprises the steps of:
- a) printing a first plurality of spaced-apart images and a second plurality of spaced-apart images, wherein the images of the first and second pluralities are at least partially aligned substantially along the printhead scan direction, wherein the images of the second plurality are spaced apart from and interleaved with the images of the first plurality, wherein the images of the first plurality are printed by one of an upper portion and a lower portion of the printhead, and wherein the images of the second plurality are printed by the other of the upper portion and the lower portion of the printhead so that in the absence of printhead skew the distance from each image of the second plurality is equidistant along the printhead scan direction from the adjacent images of the first plurality;
- b) moving a sensor in the printhead scan direction over the images of the first and second pluralities;
- and
- c) calculating a function of the output of the sensor, wherein the calculated function indicates the skew of the printhead,
- wherein the images of the first and second pluralities are sized to each completely fill the field of view of the sensor.
2 more elements
Dependencies are inferred from the claim text.