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: A method of correcting output image squareness in a laser printer system having a Raster Output Scanning (ROS) device with a pivotal mounting. The method includes printing a test pattern that includes a plurality of markers printed in a predetermined geometric arrangement and calculating a skew angle based on the measured distances, preferably using the Law of Cosines. The ROS device is then automatically rotated by an amount sufficient to correct the skew angle. The ROS rotation is performed automatically by an adjustment system connected to the ROS. The method optionally includes a scanner for scanning the test pattern image and making the measurements automatically via a program configured to analyze the scanned image.

Abstract: A method for repositioning a mark on a belt after an image on paper registration process, which includes printing a test pattern, measuring at least one test pattern parameter, detecting a mark on a belt and detecting at least one imaging error associated therewith, using the at least one test pattern parameter and the at least one imaging error to determine the lateral distance required to shift a particular image to a desired location on the belt and shifting the image to the desired location.

Abstract: A method for preserving image squareness and image on image registration in a system having a plurality of imaging stations, each imaging station having an ROS. The method includes adjusting the target skew of a reference ROS within one of the plurality of imaging stations by the angular difference between the actual reference ROS position and the target position for the reference ROS and adjusting the target skew of the reference ROS by the skew of the reference ROS relative to the desired skew for image squareness.

Abstract: The relationship between first and second side images is evaluated to determine how the position of the paper and/or the size and arrangement of an image can be manipulated to compensate for paper shrinkage caused by fusing. Show through is reduced by performing setup to adjust a pixel clock frequency and/or a photoreceptor speed, determining a residual magnification error, determining margin shifts to compensate for the residual magnification error, and applying the margin shifts. Paper shrink effects on registration can be compensated for using determinations made during a typical printer setup. Show through errors can be reduced without using a paper conditioner to pre-shrink or re-wet the paper. In simplex and duplex printing, the show through errors worsen as the image moves away from the registration edge. Using information obtained during setup, a margin shift is determined that results in a significant reduction in the maximum show through for each image.

Abstract: Initial setup of image to sheet (IOS) or image to paper (IOP) registration in a printing device such as, for example, an electrographic printer, is accomplished in a single step that uses an initial set of measurements to determine and correct each of the independent registration errors, including image squareness/ROS skew, image skew/paper skew, lateral magnification, process magnification, lateral direction IOS or IOP position, and process direction IOS or IOP position simultaneously. A set of algorithms is used to perform a series of geometrical transformations to determine each of the six errors affecting IOS or IOP registration.

Abstract: A method for repositioning a mark on a belt after an image on paper registration process, which includes printing a test pattern, measuring at least one test pattern parameter, detecting a mark on a belt and detecting at least one imaging error associated therewith, using the at least one test pattern parameter and the at least one imaging error to determine the lateral distance required to shift a particular image to a desired location on the belt and shifting the image to the desired location.

Abstract: The relationship between first and second side images is evaluated to determine how the position of the paper and/or the size and arrangement of an image can be manipulated to compensate for paper shrinkage caused by fusing. Show through is reduced by performing setup to adjust a pixel clock frequency and/or a photoreceptor speed, determining a residual magnification error, determining margin shifts to compensate for the residual magnification error, and applying the margin shifts. Paper shrink effects on registration can be compensated for using determinations made during a typical printer setup. Show through errors can be reduced without using a paper conditioner to pre-shrink or re-wet the paper. In simplex and duplex printing, the show through errors worsen as the image moves away from the registration edge. Using information obtained during setup, a margin shift is determined that results in a significant reduction in the maximum show through for each image.

Abstract: The relationship between first and second side images is evaluated to determine how the position of the paper and/or the size and arrangement of an image can be manipulated to compensate for paper shrinkage caused by fusing. Show through is reduced by performing setup to adjust a pixel clock frequency and/or a photoreceptor speed, determining a residual magnification error, determining margin shifts to compensate for the residual magnification error, and applying the margin shifts. Paper shrink effects on registration can be compensated for using determinations made during a typical printer setup. Show through errors can be reduced without using a paper conditioner to pre-shrink or re-wet the paper. In simplex and duplex printing, the show through errors worsen as the image moves away from the registration edge. Using information obtained during setup, a margin shift is determined that results in a significant reduction in the maximum show through for each image.

Abstract: The disclosed embodiments are directed to a method and apparatus for duplex imaging in a tandem print engine system. The features of the disclosed embodiments include imaging a first side of a sheet in a first marking module in the system, inverting the sheet, and imaging a second side of the sheet in a second marking module in the system one pitch after N revolutions of a photoreceptor following the first side imaging.

Abstract: Initial setup of image to sheet (IOS) or image to paper (IOP) registration in a printing device such as, for example, an electrographic printer, is accomplished in a single step that uses an initial set of measurements to determine and correct each of the independent registration errors, including image squareness/ROS skew, image skew/paper skew, lateral magnification, process magnification, lateral direction IOS or IOP position, and process direction IOS or IOP position simultaneously. A set of algorithms is used to perform a series of geometrical transformations to determine each of the six errors affecting IOS or IOP registration.

Abstract: A method of correcting output image squareness in a laser printer system having a Raster Output Scanning (ROS) device with a pivotal mounting. The method includes printing a test pattern that includes a plurality of markers printed in a predetermined geometric arrangement and calculating a skew angle based on the measured distances, preferably using the Law of Cosines. The ROS device is then automatically rotated by an amount sufficient to correct the skew angle. The ROS rotation is performed automatically by an adjustment system connected to the ROS. The method optionally includes a scanner for scanning the test pattern image and making the measurements automatically via a program configured to analyze the scanned image.

Abstract: The disclosed embodiments are directed to duplex imaging in a tandem print engine system. The features of the disclosed embodiments include imaging a first side of a sheet in a first marking module in the system, inverting the sheet, and imaging a second side of the sheet in a second marking module in the system one pitch after N revolutions of a photoreceptor following the first side imaging.

Abstract: The relationship between first and second side images is evaluated to determine how the position of the paper and/or the size and arrangement of an image can be manipulated to compensate for paper shrinkage caused by fusing. Show through is reduced by performing setup to adjust a pixel clock frequency and/or a photoreceptor speed, determining a residual magnification error, determining margin shifts to compensate for the residual magnification error, and applying the margin shifts. Paper shrink effects on registration can be compensated for using determinations made during a typical printer setup. Show through errors can be reduced without using a paper conditioner to pre-shrink or re-wet the paper. In simplex and duplex printing, the show through errors worsen as the image moves away from the registration edge. Using information obtained during setup, a margin shift is determined that results in a significant reduction in the maximum show through for each image.

Abstract: In high speed reproduction apparatus in which closely spaced printed sheets are sequentially fed downstream in a sheet path at a process velocity, a dual inverter system of two independent but cooperative sheet inverters is sheet control gated to receive alternate sheets from the sheet path for inversion in the alternate independent sheet inverters. These dual alternate sheet inverters may advantageously operate at substantially the same sheet velocity as the connecting sheet path, instead of the much higher speed and acceleration/deceleration typical of conventional single inverter systems. Yet the original collated sequential sheet order is maintained. The two independent but cooperative alternate sheet inverters may be operatively connected in series spaced along the sheet path to be alternatingly fed alternate sheets from the sheet path by separate gates and to return sheets to the same sheet path at different locations, or, connected in parallel with the sheet path by a single decision gate.

Abstract: A method and apparatus for inverting sheets traveling through a machine with an inverter having a reversing chute and a reversing nip in the reversing chute. An incoming sheet is receiving into the reversing chute. The reversing nip reverses the direction of travel of the sheet and drives sheet out of the reversing chute. A gap is opened in said reversing nip, while the outgoing sheet still extends through the reversing nip. A subsequent incoming sheet is received into the reversing chute and through the gap in the reversing nip, while the outgoing sheet still extends through the gap. The gap is closed after the outgoing sheet has exited the reversing nip, such the reversing nip reverses the direction of travel of the subsequent incoming sheet and drives the sheet out of the reversing chute. The machine may be a printing or copying machine.

Abstract: A method and apparatus for inverting sheets traveling through a machine with an inverter having a reversing chute and a reversing nip in the reversing chute. An incoming sheet is receiving into the reversing chute. The reversing nip reverses the direction of travel of the sheet and drives sheet out of the reversing chute. A gap is opened in said reversing nip, while the outgoing sheet still extends through the reversing nip. A subsequent incoming sheet is received into the reversing chute and through the gap in the reversing nip, while the outgoing sheet still extends through the gap. The gap is closed after the outgoing sheet has exited the reversing nip, such the reversing nip reverses the direction of travel of the subsequent incoming sheet and drives the sheet out of the reversing chute. The machine may be a printing or copying machine.

Abstract: In color printing with a color registration system for the registration of plural color images on an image bearing surface, such as a photoreceptor belt of a color printer, registration marks are imaged on the image bearing surface, which registration marks correspond to the color images and are sensed by a registration marks sensor. In an initial gross registration mode the system first automatically images first registration marks, in the form of expanded chevron targets, which are greatly expanded in the process direction so as to avoid overlapping marks even if there is initial gross misregistration, to thus provide wider initial misregistration latitude for the sensor. When an acceptable initial registration is achieved, the system automatically switches to imaging more closely spaced and more frequent second registration marks, preferably regular chevron targets, providing higher registration accuracy.