Method for determining printhead misalignment of a printer

A method for determining a printhead misalignment of an inkjet printer comprising the steps of:

• a) printing a printhead alignment test pattern including a plurality of spaced-apart block images at least partially aligned substantially along a printhead scan axis;
• b) moving a printhead-carriage-mounted optical sensor along the printhead scan axis at a known printhead carriage speed over the plurality of block images;
• c) obtaining sampled data points from the optical sensor at a known sampling rate;
• d) determining the locations along the printhead scan axis of the edges of the plurality of block images using the sampled data points, the known printhead carriage speed of the optical sensor, and the known sampling rate;
• and
• e) calculating the printhead misalignment from the determined locations of the edges of the plurality of block images.

A method for determining a printhead misalignment of a printer comprising the steps of:

• a) printing a printhead alignment test pattern including a plurality of spaced-apart images at least partially aligned substantially along a printhead scan axis;
• b) moving a sensor along the printhead scan axis at a known speed over the plurality of images;
• c) obtaining sampled data points from the sensor at a known sampling rate, wherein the sampled data points are obtained as digitized data points from an analog-to-digital converter whose input is operatively connected to the output of the optical sensor;
• d) determining the locations along the printhead scan axis of the edges of the plurality of images using the sampled data points, the known speed of the sensor, and the known sampling rate, wherein the digitized data points of the odd-numbered images are compared against a first threshold value to determine the locations of the edges of the odd-numbered images, and wherein the digitized data points of the even-numbered images are compared against a second threshold value to determine the locations of the edges of the even-numbered images;
• and
• e) calculating the printhead misalignment from the determined locations of the edges of the plurality of images.

A method for determining a printhead misalignment of a printer comprising the steps of:

• a) printing a printhead alignment test pattern including a plurality of spaced-apart images at least partially aligned substantially along a printhead scan axis;
• b) moving a sensor along the printhead scan axis at a known speed over the plurality of images;
• c) obtaining sampled data points from the sensor at a known sampling rate, wherein the sampled data points are obtained as digital data points from a bi-stable comparator whose input is operatively connected to the output of the optical sensor, and wherein the bi-stable comparator compares the optical sensor output to a single threshold value to set the state of the digital data point output of the bi-stable comparator;
• d) determining the locations along the printhead scan axis of the edges of the plurality of images using the sample numbers which correspond to changes of state of the digital data points, the known speed of the sensor, and the known sampling rate;
• and
• e) calculating the printhead misalignment from the determined locations of the edges of the plurality of images.