Abstract: A three-dimensional object printer ejects drops of a build material from a plurality of ejectors in a first printhead to form an object on a first region of a member and ejects drops of a support material from a plurality of ejectors in a second printhead to support the object on the first region of the member. The second printhead ejects drops of the support material onto a second region of the member that is separate from the first region to form a substrate layer. The first printhead ejects drops of the build material onto the substrate layer to form a printed test pattern. An image sensor generates image data of the printed test pattern to identify an inoperable ejector in the first printhead.

Abstract: A printer uses closed loop control to keep material drops ejected by a printhead within a predetermined range. The printer forms at least two objects on a support member and then operates a specular sensor array to obtain image data of the two objects on the support member. The two objects have different predetermined heights to enable a controller in the printer to identify the mass or volume of the material drops forming the objects to adjust operational parameters of the printer to maintain the mass or volume of the material drops in the predetermined range.

Abstract: A printer compensates for printing errors occurring during production of the layers for the formation of an object in a three-dimensional printer. The printer includes an optical sensor that generates data corresponding to edges of each layer of the object after each layer is printed. Differences between the raster data used to eject the material to form a layer and the data received from the optical sensor are used to modify the raster data that operates a printhead to form a next layer in the object.

Abstract: A three-dimensional object printer ejects drops of a build material from a plurality of ejectors in a first printhead to form an object on a first region of a member and ejects drops of a support material from a plurality of ejectors in a second printhead to support the object on the first region of the member. The second printhead ejects drops of the support material onto a second region of the member that is separate from the first region to form a substrate layer. The first printhead ejects drops of the build material onto the substrate layer to form a printed test pattern. An image sensor generates image data of the printed test pattern to identify an inoperable ejector in the first printhead.

Abstract: A printer compensates for printing errors occurring during production of the layers for the formation of an object in a three-dimensional printer. The printer includes an optical sensor that generates data corresponding to edges of each layer of the object after each layer is printed. Differences between the raster data used to eject the material to form a layer and the data received from the optical sensor are used to modify the raster data that operates a printhead to form a next layer in the object.

Abstract: A printer uses closed loop control to keep material drops ejected by a printhead within a predetermined range. The printer forms at least two objects on a support member and then operates a specular sensor array to obtain image data of the two objects on the support member. The two objects have different predetermined heights to enable a controller in the printer to identify the mass or volume of the material drops forming the objects to adjust operational parameters of the printer to maintain the mass or volume of the material drops in the predetermined range.

Abstract: Devices and methods detect an amount of toner on a photoreceptor caused by a printing process, and calculate a reload signal using a processor. The reload signal shows the amount of toner being reloaded on a donor roll from a toner container to replace the toner being removed from the donor roll during the printing process (as detected by an optical sensor). Such devices and methods generate a toner concentration (TC) sensor response representing a concentration of toner particles within the toner/developer mixture using a TC sensor, calculate a calibration sensor relationship between the TC sensor response and the reload signal, using the processor, based on changes in the TC sensor response and the reload signal that occur while changing the toner concentration during the printing process, and calibrate the TC sensor based on differences between the calibration sensor relationship and a previously established model relationship using the processor.

Abstract: A method of printer operation enables visual detection of defective inkjets. The method includes operating inkjets in a predetermined number of printheads that eject a same color of ink to form a test pattern having three portions. One portion is printed by the even-numbered inkjets in each printhead, one portion is printed by the odd-numbered inkjets in each printhead, and a third portion is printed by all of the inkjets in each printhead. The portions are printed immediately adjacent to one another in a process direction with the third portion between the other two portions.

Abstract: A method of printer operation enables visual detection of defective inkjets. The method includes operating inkjets in a predetermined number of printheads that eject a same color of ink to form a test pattern having three portions. One portion is printed by the even-numbered inkjets in each printhead, one portion is printed by the odd-numbered inkjets in each printhead, and a third portion is printed by all of the inkjets in each printhead. The portions are printed immediately adjacent to one another in a process direction with the third portion between the other two portions.

Abstract: A method of calibrating a printing system for positioning at least one printed image, the printing system includes a first image bearing surface, the method includes: a) forming a background pattern and at least three fiducials on the first image bearing surface, wherein the background pattern is larger than a first printed image and the at least three fiducials are within an area formed by the first printed image; b) transferring a portion of the first printed image to a second image bearing surface; c) measuring a first residual image on the first image bearing surface, wherein the first residual image is a portion of the background pattern and the at least three fiducials remaining on the first image bearing surface after the step of transferring; and, d) calculating at least one calibration parameter for the printing system based on the measuring of the first residual image.

Abstract: Line width of images marked by an image marking device is adjusted by reading a calibration patch marked by the marking device, and then adjusting one or more settings of the marking device, such as exposure intensity or cleaning field intensity, independent of the digital control of the tone reproduction curve so that the line width of subsequently marked images becomes closer to a target value. A digital control may be implemented to compensate for the impact of the modification of the one or more settings on the tone reproduction curve.

Abstract: Streak compensation in a digital printer is provided utilizing a spatially varying Printer Model and Run Time updates to generate Spatially Varying Tone Reproduction Curves (STRCs) which are used as actuators to compensate for streaks during run time. A full width array sensor is used to measure streak profiles and the STRCs are used as actuators to compensate for streaks. Streak profile measurements taken at a limited number of area coverage levels combined with a Printer Streaks Basis Function Model are used to estimate and project the streak behavior at all area coverage levels and at all inboard-to-outboard spatial locations. The projection is then used in a pixel-wise error feedback control scheme to drive each profile to a desired shape, thereby compensating for streaks.

Abstract: A method for monitoring an image printing system that prints color images on an image bearing surface movable in a process direction is provided. The method includes placing marking material to form a row comprising a plurality of registration marks on the image bearing surface, wherein each row of registration marks extends along a cross-process direction transverse to the process direction; detecting a position of each registration mark using a linear array sensor extending in the cross-process direction, wherein the position of each registration mark is detected in both the process and cross-process direction; determining a process direction misregistration between the registration marks of each row in the process direction and cross-process direction misregistration between registration marks from each of the rows.

Abstract: A method of calibrating a printing system for positioning at least one printed image, the printing system includes a first image bearing surface, the method includes: a) forming a background pattern and at least three fiducials on the first image bearing surface, wherein the background pattern is larger than a first printed image and the at least three fiducials are within an area formed by the first printed image; b) transferring a portion of the first printed image to a second image bearing surface; c) measuring a first residual image on the first image bearing surface, wherein the first residual image is a portion of the background pattern and the at least three fiducials remaining on the first image bearing surface after the step of transferring; and, d) calculating at least one calibration parameter for the printing system based on the measuring of the first residual image.

Abstract: Line width of images marked by an image marking device is adjusted by reading a calibration patch marked by the marking device, and then adjusting one or more settings of the marking device, such as exposure intensity or cleaning field intensity, independent of the digital control of the tone reproduction curve so that the line width of subsequently marked images becomes closer to a target value. A digital control may be implemented to compensate for the impact of the modification of the one or more settings on the tone reproduction curve.

Abstract: A marking device is controlled to mark a media sheet with halftone dots selected from a set of image halftone dot representations. The marking device is controlled to mark a monitored surface with halftone dots selected from a set of control halftone dot representations to form test patches of different nominal marking densities. Measured marking densities are acquired using a density sensor for the test patches marked on the monitored surface. The set of control halftone dot representations is updated based on the measured marking densities and the nominal marking densities.

Abstract: Disclosed is a printing apparatus and method to correct for image non-uniformities. The printing apparatus comprises a photoreceptor (P/R) belt charging device positioned to charge the P/R belt after an image is transferred to a media sheet. Subsequently, an image sensing device scans the P/R belt residual image or patches to detect image non-uniformities.

Abstract: Streak compensation in a digital printer is provided utilizing a spatially varying Printer Model and Run Time updates to generate Spatially Varying Tone Reproduction Curves (STRCs) which are used as actuators to compensate for streaks during run time. A full width array sensor is used to measure streak profiles and the STRCs are used as actuators to compensate for streaks. Streak profile measurements taken at a limited number of area coverage levels combined with a Printer Streaks Basis Function Model are used to estimate and project the streak behavior at all area coverage levels and at all inboard-to-outboard spatial locations. The projection is then used in a pixel-wise error feedback control scheme to drive each profile to a desired shape, thereby compensating for streaks.

Abstract: A method for monitoring an image printing system that prints color images on an image bearing surface movable in a process direction is provided. The method includes placing marking material to form a row comprising a plurality of registration marks on the image bearing surface, wherein each row of registration marks extends along a cross-process direction transverse to the process direction; detecting a position of each registration mark using a linear array sensor extending in the cross-process direction, wherein the position of each registration mark is detected in both the process and cross-process direction; determining a process direction misregistration between the registration marks of each row in the process direction and cross-process direction misregistration between registration marks from each of the rows.

Abstract: A marking device is controlled to mark a media sheet with halftone dots selected from a set of image halftone dot representations. The marking device is controlled to mark a monitored surface with halftone dots selected from a set of control halftone dot representations to form test patches of different nominal marking densities. Measured marking densities are acquired using a density sensor for the test patches marked on the monitored surface. The set of control halftone dot representations is updated based on the measured marking densities and the nominal marking densities.