Abstract: This invention relates to a method for the calibration of linear array photo sensors operating in a specular reflection mode. Errors may be introduced when a highly diffused image is measured by the linear array photosensor that was calibrated in a specular mode. These errors result in artifacts such as streaks in the captured image. The method measures non-uniformity errors using a highly diffuse white reflective surface, and then applies an appropriate scaled pixel-wise correction factor to the image when the sensor is used in the specular mode.

Abstract: A method of measuring and correcting the Young's Modulus inline to eliminate its impact on image length variation during print runtime. The method includes intentionally perturbing the nominal operating condition of the web printing system which is controlled by the double reflex printing controller. The perturbation creates misregistration in a control target printed image that is detectable by in-situ sensors, from which Young's Modulus is estimated. Specifically, the web tension before the print zone is set differently from the web tension in the print zone to create misregistration. The error is detected by the inline sensors, and it is used to calculate the actual Young's Modulus. The implementation of the method consists of measuring the Young's Modulus at various frequencies. The correct Young's Modulus in then incorporated into the double reflex printing algorithm.

Abstract: Optical measurement system and method for determining a wear level of printer components such as fuser rolls. Papers can be treated with optical brighteners, which act as distinct tag/trace molecules with fluorescent properties. A fluorescence pattern on the fuser roll can be changed in accordance with the edge density distribution in the print engine, when paper edges are accumulated on the fuser roll surface. A photo detector can capture a two-dimensional, digital image of the fluorescence pattern on the fuser roll surface to be measured, after illuminating the fuser roll, with intensity near ultraviolet range, by a light source. An image processor with a parameterized model can measure changes in the fluorescence pattern by analyzing the digital image of the fuser roll surface in order to determine the level of edge wear on the fuser rolls.

Abstract: Systems and methods are provided for monitoring jets of an image device. The detection is implemented using a data processor that monitors information sent to a jet and using an image sensor that monitors an image being printed or an image after being printed. A detector detects the difference between the image being printed and/or the image after printing to the information sent to the jet, and identifies a faulty jet based on the difference detected.

Abstract: A method of aligning a printhead is described herein. The method includes accelerating a media along a process path, controlling a first printhead to form a first mark upon the accelerating media, detecting the first mark on the accelerating media, comparing a first mark detection data with first printhead desired alignment data, determining a first correction based upon the comparison of the first mark detection data, and modifying an alignment of the first printhead based upon the determined first correction.

Abstract: A developer unit used in xerographic printing retains a mixture of at least a first colorant and a second colorant. An illuminator directs toward at least a portion of the mixture a first light of one color, a second light of a second color, and a third light substantially outside of a visible range. A photosensor records a first reflectance signal based on light reflected from the mixture substantially in a visible range, and a second reflectance signal based on light reflected from the mixture substantially outside a visible range. The signals can be used to maintain the mixture at the desired total color and other properties.

Abstract: A method and system for color calibration or color output device spectrophotoically measures at test target including a preselected test color value. A multi-dimensional LUT of the device is generated representative of the color information including the at least one preselected color. Producing a second image width device including the at least one preselected color located at a plurality of spatial locations in the second image. A second sensor measures the second image and a plurality of spatial locations having the preselected color for generating reflectance information for the preselected color at the plurality of spatial locations. An error is determined between the measured color of the one preselected color and the reflectance information at the other pixel locations. A multi-dimensional LUT is adjusted to minimize spatial uniformity errors at the other pixel locations, thus calibrating device color output spatially.

Abstract: Systems and methods are provided for compensating for streak defects in images formed by an image forming device, such as a digital printer. The systems and methods include using both modulation of a raster output scanner (ROS actuation) and spatially varying tone reproduction curve (STRC actuation) in a common control system for improving streak correction. Low spatial frequency large amplitude streak defects are corrected using ROS actuation and high spatial frequency streak defects, as well as any residual low frequency defects, are corrected using STRC actuation.

Abstract: A system and method for optically monitoring contamination of machinery includes an optical illumination source, a photodetector and an analysis module. The system and method can monitor a fuser roll, a fuser belt, or other printer module component. The optical illumination source can emit at least one illuminating frequency. The at least one illuminating frequency is configured to cause a contaminant marker to fluoresce at least one fluorescing frequency and is also configured to at least partially illuminate the machine component. The machine component contains the contaminant marker when at least partially contaminated. The photodetector is responsive to the at least one fluorescing frequency and detects the at least one fluorescing frequency emitted from the contaminated machine component. The analysis module is in operative communication with the photodetector and is figured to receive a signal therefrom.

Abstract: This invention relates to a method for the calibration of linear array photo sensors operating in a specular reflection mode. Errors may be introduced when a highly diffused image is measured by the linear array photosensor that was calibrated in a specular mode. These errors result in artifacts such as streaks in the captured image. The method measures non-uniformity errors using a highly diffuse white reflective surface, and then applies an appropriate scaled pixel-wise correction factor to the image when the sensor is used in the specular mode.

Abstract: The method and system for printer color calibration use a combination of a full-width array (FWA) or similar page-scanning mechanism in conjunction with a spectrophotometer color measurement system in the output path of a color printer for measuring colors with or without requiring any manual operations or operator involvement. The automatic color balance control system produces spatial tonal reproduction values for the primary colors by printing patches, measuring colors using the sensor combination and automatically readjusting the spatial tone reproduction curves until a satisfactory level of printed color accuracy and uniformity are obtained.

Abstract: A printing apparatus has a substantially shiny photoreceptor imaging surface, and a photosensor array disposed to receive specularly-reflected light from the imaging surface. A quantity of toner is placed on the imaging surface, and data is derived based on light reflected from the imaging surface. The reflected light is filtered to a color effectively complementary to the toner color. The system avoids noise caused by diffusely-reflected light from powdered toner.

Abstract: Many xerographic machines have a motor polygon assembly (MPA), which is a rotating polygonal mirror. As the MPA rotates, it reflects a modulated light beam to produce scan lines on a photoreceptor. Inconsistencies in the MPA can cause inconsistencies in the scan lines, and therefore banding in a printed document. Misalignment, improper mounting, improper manufacture, or sources can cause the MPA inconsistencies. The banding is periodic, can be measured and can be compensated for. Although the modulated light beam can be modulated by many sources, further modulation using a compensation source can reduce banding.

Abstract: A printer or other marking engine includes a marking material transfer device, such as a photoreceptor drum or belt, that includes a plurality of pitches. Each pitch receives an individual color of marking material and conveys the marking material to a substrate. The marking engine forms a desired image in a main image area of the substrate using marking material from one or more of the pitches, and produces a target patch pattern for each of the pitches in a margin area located outside the main image area. A measuring device such as a spectrophotometer is used to measure each target patch pattern, and based on the measured values, an individual color calibration is performed for each pitch for use in a subsequent marking operation. The color calibration may include generating or modifying a tone reproduction curve for each pitch based on the measured values. The margin area may be later trimmed off, thereby removing the portion of the substrate on which the target patch pattern is formed.

Abstract: A system that determines an amount of toner mass present on a toner application surface, and comprises a specular reflection sensor, a diffuse reflection sensor, an output combination module, and a mass determination module. The specular reflection sensor receives electromagnetic radiation that has been specularly reflected by the toner application surface, and generates a specular reflection output representative of the received electromagnetic radiation. The diffuse reflection sensor receives electromagnetic radiation that has been diffusely reflected by the toner application surface, and generates a diffuse reflection output representative of the received electromagnetic radiation. The output combination module creates a combined output by combining the specular reflection output and the diffuse reflection output with the purpose of reducing a noise source common to both specular and diffuse outputs to improve the signal to noise ratio.

Abstract: This is a charging assembly that is useful in marking processes with an electrostatically charged surface. The assembly includes, besides the charger, a controller and an electric field probe. Charge and current flows can be detected by the probe and corrected immediately after detection of flaws by the probe and conveyed to the controller. If flaws in the charger are determined by the probe, corrections are made to the output by a controller; this is done before a final copy or print is made. The term flaws as used means any non-uniform appearing region in the printed image or any void region within the printed image including any otherwise unacceptable defect such as a jagged line that is visible to an end user. The probe is enabled to detect and indicate flaws and the controller which is in communication with the probe takes corrective action on the flaws. The probe used is a novel probe having two sensing elements surrounded by one or more reference electrodes.

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 development unit used in xerographic printing retains a mixture of at least a first colorant and a second colorant. An illuminator directs toward at least a portion of the mixture a first light of one color, a second light of a second color, and a third light substantially outside of a visible range. A photosensor records a first reflectance signal based on light reflected from the mixture substantially in a visible range, and a second reflectance signal based on light reflected from the mixture substantially outside a visible range. The signals can be used to maintain the mixture at the desired total color and other properties.

Abstract: A system that determines an amount of toner mass present on a toner application surface, and comprises a specular reflection sensor, a diffuse reflection sensor, an output combination module, and a mass determination module. The specular reflection sensor receives electromagnetic radiation that has been specularly reflected by the toner application surface, and generates a specular reflection output representative of the received electromagnetic radiation. The diffuse reflection sensor receives electromagnetic radiation that has been diffusely reflected by the toner application surface, and generates a diffuse reflection output representative of the received electromagnetic radiation. The output combination module creates a combined output by combining the specular reflection output and the diffuse reflection output with the purpose of reducing a noise source common to both specular and diffuse outputs to improve the signal to noise ratio.

Abstract: A method and system for color calibration or color output device spectrophotoically measures at test target including a preselected test color value. A multi-dimensional LUT of the device is generated representative of the color information including the at least one preselected color. Producing a second image width device including the at least one preselected color located at a plurality of spatial locations in the second image. A second sensor measures the second image and a plurality of spatial locations having the preselected color for generating reflectance information for the preselected color at the plurality of spatial locations. An error is determined between the measured color of the one preselected color and the reflectance information at the other pixel locations. A multi-dimensional LUT is adjusted to minimize spatial uniformity errors at the other pixel locations, thus calibrating device color output spatially.