Abstract: In an inkjet printer, a first printhead forms a first mark on a print medium using a high-contrast ink. A second printhead forms a second mark on the first mark using a low-contrast ink. The printer generates image data of the low-contrast ink mark and the high-contrast ink, and a controller in the printer identifies a cross-process direction offset between the first printhead and the second printhead with reference to a distance between the center of the first mark and the second mark in the image data.

Abstract: A method of operating a printer to detect errors in an optical sensor includes forming a printed line across a first side of a print medium and generating first image data corresponding to the printed line with the optical sensor. The optical sensor generates second image data of the second side of the print medium as the print medium passes the optical sensor a second time. A detect in the optical sensor is identified with reference to a difference between process direction alignments of the line in the first image data and the second image data.

Abstract: A method for operating an inkjet printer to identify inoperable inkjets includes ejecting ink drops of a first color onto an image receiving surface to impose a control pattern on a document zone in addition to an ink image generated in the document zone. A density of the control pattern in the document zone changes at a rate that is at or less than a predetermined threshold. The method includes generating scanned image data of a portion of the control pattern on the image receiving surface and identifying a performance parameter corresponding to inkjets and printheads in the printer.

Abstract: A method analyzes image data of a test pattern printed on an image receiving member by a printer. The method includes identifying a process direction position for each row of dashes in a test pattern printed on an image receiving member, identifying a center of each dash in a cross-process direction, identifying an inkjet ejector that formed each dash in the row of dashes. These data are used to identify a process direction position for each printhead, a cross-process displacement for each column of printheads, and a stitch displacement in the cross-process direction between neighboring printheads in a print bar unit that print a same color of ink. An actuator can be operated with reference to the identified process direction positions, cross-process displacements, and the identified stitch displacements to move at least some of the printheads in the printer.

Abstract: A method compensates for changes in drop velocity of drops emitted by inkjets in a printhead of an ink jet imaging device. The method includes operating inkjet ejectors in a plurality of printheads to eject ink in a pattern of structured dashes on an image receiving member, the structured dashes corresponding to a predetermined image data pattern, generating image data corresponding to the pattern of structured dashes on the image receiving member, identifying a process direction correction parameter for each ejector in the plurality of printheads with reference to the generated image data, modifying image data to be printed by the plurality of printheads with reference to the process direction correction parameter identified for at least one of the ejectors, and operating the plurality of printheads with reference to the modified image data.

Abstract: A system and method for achieving registering of side 1 and side 2 images includes sensing marks on both sides of a web with a single IOWA sensor and relying on light transmission through paper to sense side 1 marks. Side 1, the side not facing the IOWA sensor utilizes increased contrast (black toner), mark width, and repeats in order to make effective image “show through.” The image of the marks on both sides of the sheet is compared with respect to each other and adjustments to some combination of position, timing, and image magnification are made as required.

Abstract: Engine response curves (RCs) can be used for streak compensation for printed documents. A feedback control paradigm can be included to effect RC compensation. Singular Value Decomposition (SVD) can be used to represent each RC in the collection of spatial RC data as a linear combination of basis vectors. RCs are approximated by selecting the first few basis vectors, the approximation aiding in noise rejection and reducing computation in the controller by reducing dimensionality of the RC data from gray levels to the number of SVD bases selected. An optimal subset of RCs is selectable from the set of approximated RCs by clustering the SVD weights, the clustered SVD weights producing TRCs that span all engine response RCs generated by a printer. Compensation RCs are constructible using reduced number of bases and clustered SVD weights.

Abstract: A leveling and spreading system has been developed that enables the speed and position of the web to be determined from a sensor on a first roller. In a duplex print process, the first roller also reduces a temperature of the media web and an ink image printed in the first side print operation to within a first predetermined temperature range. A second roller modulates the temperature of the media web and ink ejected onto the media web immediately before the web enters the leveling and spreading system to within a second predetermined temperature range to enable uniformity of the ink and web temperatures for spreading the ink in a nip formed with a third roller.

Abstract: A computer-implemented method for identifying the edges of web media transported on a movable transport surface includes sensing, using a linear array sensor positioned along a process path of a web, the web media and the movable transport surface to obtain image data representative of variations in optical textural properties of the web media and variations in optical textural properties of the movable transport surface, wherein the variations in the optical textural properties of the movable transport surface are different from the variations in the optical textural properties of the web media; and processing the image data to determine differences between the variations in the optical textural properties of the web media and the variations in the optical textural properties of the movable transport surface to identify an edge of the web media.

Abstract: Processes are presented for creating electronic banding compensation profiles for raster output scanner (ROS) devices by printing and scanning a test pattern having a series of strips extending along a process direction and spaced from one another along a cross process (fast scan) direction, analyzing the scanned data to determine facet-specific banding errors corresponding to individual strips, and selectively adjusting banding correction profiles to counteract the banding errors.

Abstract: A leveling and spreading system has been developed that enables the speed and position of the web to be determined from a sensor on a first roller. In a duplex print process, the first roller also reduces a temperature of the media web and an ink image printed in the first side print operation to within a first predetermined temperature range. A second roller modulates the temperature of the media web and ink ejected onto the media web immediately before the web enters the leveling and spreading system to within a second predetermined temperature range to enable uniformity of the ink and web temperatures for spreading the ink in a nip formed with a third roller.

Abstract: A system and method for adjusting a transport path length of a continuous web of recording media in a printing system printing duplex images. The method includes detecting alignment marks, for instance top of form (TOF) marks, on the continuous web of print media and adjusting the path length to provide substantially accurate registration of first and second images on opposite sides of the web for duplex imaging. The system to adjust path length includes idler rollers movable with respect to turnbar rollers.

Abstract: A method analyzes image data of a test pattern printed on an image receiving member by a printer. The method includes identifying a process direction position for each row of dashes in a test pattern printed on an image receiving member, identifying a center of each dash in a cross-process direction, identifying an inkjet ejector that formed each dash in the row of dashes. These data are used to identify a process direction position for each printhead, a cross-process displacement for each column of printheads, and a stitch displacement in the cross-process direction between neighboring printheads in a print bar unit that print a same color of ink. An actuator can be operated with reference to the identified process direction positions, cross-process displacements, and the identified stitch displacements to move at least some of the printheads in the printer.

Abstract: A test pattern printed by printheads in an inkjet printer enables image analysis of the test pattern that identifies positions of the printheads and the inkjets operating in the printheads. The test pattern includes a plurality of arrangements of dashes, each arrangement of dashes having a predetermined number of rows and a predetermined number of columns, each dash in a row of dashes in the arrangement of dashes being separated by a first predetermined distance and each dash in a column of dashes in the arrangement of dashes being separated by a second predetermined distance, each dash in a column of an arrangement of dashes being ejected by a single inkjet ejector in a printhead of the inkjet printer, and a plurality of unprinted areas interspersed between the plurality of arrangements of dashes.

Abstract: A method generates a test pattern on an image receiving member that is less perceptible to human observation, but still detectable by an imaging device within a printer. A method implemented in the printer analyzes image data of the dashes in the test pattern that were randomly distributed in the process direction within an area of the image receiving member to identify positions for printheads in the printer and detect missing inkjets in the printheads.

Abstract: Raster Output Scanners and printing systems are presented along with methods for mitigating banding in printing systems, in which electronic banding compensation is employed using cross-process direction light source intensity banding correction profiles tailored to corresponding reflective facets of a rotating polygon.

Abstract: A method for aligning printheads, some of which are arranged in an overlapped configuration, in a printer has been developed. The method includes identifying a stitch error for each color station in a plurality of color stations in the printer. The stitch error is identified with reference to shrinkage of a print medium as the print medium passes the plurality of color stations. A portion of the stitch error is used to move at least one printhead in the color station corresponding to the stitch error to compensate for a banding issue caused by the overlapped printhead configuration. All or part of the stitch error may also be applied to other printheads in the color station to compensate for possible color to color registration issues.

Abstract: A method enables an operator to detect misalignment of printheads that eject clear ink in an inkjet printer. The method prints a first test pattern with a first color of ink and then prints a second test pattern of clear ink on top of the first test pattern. The ink of the first and the second test patterns is then spread to enable the clear ink to be dispersed in interstitial spaces in the ink of the first color. An operator is then able to detect the spatial relationship of predetermined marks in the second test pattern to predetermined marks in the first test pattern. The predetermined marks of the first and the second test patterns are arranged to enable an operator to detect a misalignment distance and the inkjet printer uses the misalignment distance entered by the operator to adjust the alignment of the printheads that eject clear ink.

Abstract: A method of detecting print head roll begins with the formation of a test pattern on an image receiving surface. The test pattern includes a plurality of marks arrayed across the image receiving surface in a cross-process direction with each mark in the plurality being formed by a different nozzle of a print head. The cross-process direction positions of each mark in the plurality of marks are then detected; and the detected cross-process direction positions are correlated to a print head roll value for the print head.

Abstract: Processes are presented for creating electronic banding compensation profiles for raster output scanner (ROS) devices by printing and scanning a test pattern having a series of strips extending along a process direction and spaced from one another along a cross process (fast scan) direction, analyzing the scanned data to determine facet-specific banding errors corresponding to individual strips, and selectively adjusting banding correction profiles to counteract the banding errors.