Abstract: A method for calibrating a multi-printhead printing system, the method includes the steps of employing an encoder to track movement of a media through the printing system; providing a first printhead that prints a first image plane that includes a first test mark at a first defined location on the media as the media moves relative to the first printhead; providing a second printhead that prints a second image plane that includes a second test mark at a second defined location on the media as the media moves relative to the second printhead; employing a first image capture device that captures an image that includes both the first and second test marks; determining an error factor based on the placement of the second mark relative to the first mark in the captured image; and creating a frequency-shifted pulse train of the encoder in which the frequency shift is based on the error factor; wherein the first printhead prints the first image plane in response to output of the encoder and the second printhead print

Abstract: A method for calibrating a multi-color inkjet printing system includes using a 3×2 test target array. The test target includes printing a first color three times in which two of the three colors are aligned along a first axis and the third is offset from the first axis and at a midway point between the other two test marks along the other axis. A second test color is aligned with at least one of the first colors along both axes.

Abstract: A method for capturing an image in a multi-color printing system, the method includes the steps of providing a test pattern on a print media having a plurality of test patterns aligned in a first direction in a repeating pattern; providing an image capture device having a shutter that controls a time interval during which a single image is captured; and flashing a strobe light multiple times within the time interval in which a single image is captured; wherein each strobe light flash is synchronized with motion of the test pattern past the image capture device so that each test pattern is illuminated by a single strobe-light flash at substantially the same location within the captured image.

Abstract: A method for calibrating a multi-color inkjet printing system includes using a 3×2 test target array. The test target includes printing a first color three times in which two of the three colors are aligned along a first axis and the third is offset from the first axis and at a midway point between the other two test marks along the other axis. A second test color is aligned with at least one of the first colors along both axes.

Abstract: A method for calibrating a multi-printhead printing system, the method includes the steps of employing an encoder to track movement of a media through the printing system; providing a first printhead that prints a first image plane that includes a first test mark at a first defined location on the media as the media moves relative to the first printhead; providing a second printhead that prints a second image plane that includes a second test mark at a second defined location on the media as the media moves relative to the second printhead; employing a first image capture device that captures an image that includes both the first and second test marks; determining an error factor based on the placement of the second mark relative to the first mark in the captured image; and creating a frequency-shifted pulse train of the encoder in which the frequency shift is based on the error factor; wherein the first printhead prints the first image plane in response to output of the encoder and the second printhead print

Abstract: A method for evaluating the stability of print module registration for a printer creates an innovative test pattern by forming two graphic images from two separate print modules. The graphic images include parallel graphic information and a desired intersection point. The graphic images are printed on by a pixel by pixel basis onto print media from the separate print modules. The resulting patterned image or test pattern is viewed to ascertain alignment based on the desired intersection point.

Abstract: An ink jet ink composition comprises a liquid vehicle, a pigment, a pH adjusting component, and a chemical with a plurality of electron donating groups. The chemical with a plurality of electron donating groups comprises a chemical with at least three electron donating groups, wherein the at least three electron donating groups are situated in close proximity to provide high dried film resistivity. With the present invention, significant improvement in dried film resistivity of carbon pigment ink jet inks is achieved, sufficient to eliminate charge lead to charge lead shorts and improve machine runnability and can, therefore, be used in ink jet printers.

Abstract: Ink concentration in a system is maintained regardless of the duty cycle under which the system is operating. In an ink jet system, a print head receives ink from the main ink supply and forms continuous drops. The drops needed for printing to form the desired image are selected from the continuously formed drops. Based on the selection, a count signal is produced indicative of the number of drops printed. An ink level sensor in the main ink reservoir generates a low ink level signal when ink in the reservoir reaches a predetermined low level, the difference between a normal level and the low level corresponding to a predetermined cycle volume. A fluid connection selectively allows flow into the main ink reservoir from either the external supply of ink or the external supply of ink replenisher.

Abstract: A system and method for emptying a refill container used in a continuous ink jet fluid system reduces the amount of ink left in the refill container and eliminates adverse effects in the event that air enters the fluid system through the refill apparatus. The system for emptying the container includes a system vacuum and a refill container. A bi-directional path is provided between the system vacuum and the refill container. The air is then removed from the refill container while maintaining the system vacuum within a predetermined range.

Abstract: A sheet stacking apparatus for receiving sheets from a printing or copying machine includes guide structure for directing output sheets onto an elevator platform and a selectively rotatable shaft having paddle arms disposed at a 108.degree. interval. The shaft rotation is controlled so that the arms guide a sheet during stacker input and then rotates 360.degree. to positively clear the sheet trail edge from the stacker input path.