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: An automatic gray balance control system to produce TRCs for all primary colors in a reproduction device and for each pitch of a photoreceptor system by printing target patches for each pitch, measuring the output colors, and automatically readjusting the tone reproduction curves until a satisfactory level of accuracy is obtained as compared to the theoretical desired output. The system produces pitch-based gray balanced TRCs that are updated frequently for each pitch, with different TRCs for different pitches, to ensure consistency in output from pitch to pitch as well as from page to page on a given pitch.

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 an spectrophotometer color measurement system in the output path of a color printer for measuring colors (e.g., on printed test sheets, banner/separation pages, etc.) with or without requiring any manual operations or operator involvement. The automatic color balance control system produces spatial tonal reproduction values for all four of 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. While producing color balanced TRCs, the system will automatically lock the printer output to some predetermined color patch targets. In one particular preferred embodiment, this output is locked to neutral gray when target colors are set to neutral gray inside the digital front end (DFE).

Abstract: Systems and method provide compensation for temperature induced peak wavelength shift of LEDs is color parameter measuring systems that use a model to reconstruct target color parameter values from the reflectance values measured when the target is illuminated by LEDs. Several models may be constructed, with each model being trained at a unique temperature, resulting in a set of models that span the temperature range of interest. In real-time, the LED based color parameter measuring system measures the temperature and interpolates between the models to estimate the appropriate model to use at the temperature of interest. The estimated model is then used to perform the color parameter value estimation.

Abstract: Tone reduction curves are utilized to map an input value to an output value. A tone reduction curve is normally produced by an algorithm that fits a curve to a series of knots. Knots can be determined from calibration data. Printing a calibration patch pattern yields a target patch pattern. The desired reflectances of the calibration patches and the measured reflectances of target patches can be used as calibration data. The series of knots can also include a highlight knot and a shadow knots so that the tone reduction curve functions better in the highlight and shadow regions.

Abstract: A method for calibrating a printing system including a plurality of printers includes designating one of the plurality of printers as a reference printer and defining color values for a desired response for one or more printed test patches on a control page. Through a first process aimed toward achieving the desired response, a printed control page is generated with the reference printer, the control page including one or more of the test patches which, when measured, has a measured response which approaches the desired response. Through a second process aimed toward achieving a desired response, the desired response being the measured response of the reference printer, a printed control page is generated with a second of the printers, the control page including one or more of the test patches which, when measured, has a response which approaches the measured response of the reference printer.

Abstract: A developer apparatus for developing an image, including a sump for storing a quantity of developer material comprised of toner of a first color and carrier material, a donor member for developing the image with toner; an auger for transporting developer material within the sump; a toner concentration sensor for sensing toner concentration in the sump, the toner concentration sensor including a viewing window, in communication with developer material in the sump, an optical sensor for measuring reflected light off the developer material and a cleaning member coacting with the auger to clean the viewing window; and a system for generating a signal indicative of the toner concentration in the sump.

Abstract: A device to measure toner concentration can include a selector that selects a type of developer material to be measured and a sensor that detects an amount of light reflected off a developer material. A controller within the device can determine a value corresponding to a toner concentration of the developer material based on the amount of light detected by the sensor.

Abstract: A method of measuring and controlling high frequency banding, the method includes creating a test pattern, sensing the test pattern with optical sensors, determining a beat frequency based on the sensed test pattern, and determining the frequency, phase and amplitude of high frequency banding based on the beat frequency. An exemplary embodiment of a feedback control method for controlling high frequency banding includes creating a test pattern, sensing the test pattern with optical sensors, measuring high frequency banding and adjusting the imaging parameters based on the measured high frequency banding in order to decrease the extent of high frequency banding. Moreover, an exemplary embodiment of a system for measuring high frequency banding includes an image marking device having a receiving member, optical sensors arranged on the receiving member, and a controller that is functionally coupled to the optical sensors and to the marking device.

Abstract: Systems and methods of controlling banding defects on a receiving member in an imaging or printing process using a feedback and/or feedforward control technique. In one exemplary embodiment, a method of controlling banding defects on a receiving member in an imaging or printing process includes (a) determining a toner density on the receiving member, (b) automatically determining the extent of banding on the receiving member by comparing the determined toner density to a reference toner density value, and (c) automatically adjusting the toner density based on a result obtained from the comparison of the measured toner density to the reference toner density value, automatically determining the extent of banding and automatically adjusting the toner density being performed using a feedback and/or feedforward control routine or application.

Abstract: A feedback control method for controlling an ununiform banding on a photoreceptor is disclosed that includes arranging optical sensors on a photoreceptor, transferring an amount of toner on a piece of paper, measuring the resulting amount of banding, and adjusting the parameters to decrease the amount of banding. A method of measuring low deposited masses of a substrate is disclosed, using either ETAC optical sensors or full width array sensors. Finally, a copy is disclosed including at least one of NC2 array sensors and ETAC sensors, a developer roll voltage source, a ROS intensity source, an input device and a controller.

Abstract: What is disclosed is a method for maintaining consistent color output across printers even when the inline sensors have differences in accuracy due to various technical and environmental factors. A spectrophotometer is used to measure the color quality of printed references. Adjustments are then iteratively made until reference charts of desired color quality are obtained. The printed reference allows one to achieve relatively high system performance by removing sensor inaccuracies. Using the printed reference measured by the inline sensor control systems of each machine are calibrated. At customer sites and at suitable intervals, a reference document can be read using the inline sensor on a reference machine and any differences from expected values can be calibrated out.