Xerox Corporation

Other

Robert E Grace

James M Pacer

Robert M Mara

John G Elliot

Angelo T Caruso

Daniel C Roehrs

Patricia J Saraceno

Lalit Keshav Mestha

Yao Rong Wang

William H Wayman

Fred F Hubble, Iii

Grace T Brewington

Michael C Mongeon

Guru B Raj

Tonya L Love

Gary Walker Skinner

Rasin Moser

Mark A Gwaltney

Kenneth James Buck

Krzysztof J Less

Eric Jackson

Larry G Hogestyn

Thomas A Hayes, Jr

Dennis M Diehl

Jeffrey C Folkins

Hugh W Griffith

Tim D M Enskat

Using a document scanner or other image input device of an image or document processing system to periodically scan or image printed test images from a plurality of marking engines replaces internal sensors as a feedback means in image quality control. For example, image lightness (L*) is controlled by periodically printing mid-tone test patches, scanning the printed test patches with a main job document scanner and analyzing the scanned image to determine updated marking engine actuator set points. For instance, ROS exposure and/or scorotron grid voltages are adjusted to maintain image lightness consistency between marking engines.

Semi-automatic image quality adjustment for multiple marking engine systems

A method for minimizing toner usage in minimum area coverage patches in a color printer including: reviewing a print job including job images; performing a pixel count for each color plane on a sheet level of the print job; converting the pixel count to a percent area coverage per color plane; in feed-forward mode comparing the area coverage per color plane to a reference value; activating or inactivating a color station depending on the comparison of the area coverage per color plane to the reference value; and printing a MAC patch of variable size with the color station if the area coverage per color plane is substantially less than a reference value.

Process for minimizing toner usage in minimum area coverage patches and minimizing toner churning

An image transfer apparatus with the capacity to reduce or clean wire history. The cleaning is performed by supplying a voltage burst to shift, relative to nominal, the D.C. component of the electrode bias relative to the electrical bias of the donor member during the movement of the inter-imaging region through the development zone. A voltage shift may also be applied to electrically bias the donor member relative to the photoreceptor belt during the movement of the inter-imaging region through the development zone. These voltage shifts may be conducted individually or simultaneously.

Hybrid scavengeless development using direct current voltage shift to remove wire history

In a color analysis method in which sheets with multiple different color printed test patches are moved relative to a color analyzing spectrophotometer, and in which fiducial marks are printed adjacent to respective test patches and optically detected by a fiducial mark detector to provide a triggering system for the respective test patch analysis, there is provided automatic diagnostic testing of the spectrophotometer and the fiducial mark triggering system, including automatically generating special test sheets, some of which may include test areas of varying density black.

Diagnostics for color printer on-line spectrophotometer control system

In an electrophotographic imaging system, a toner density control method and apparatus that uses software modeling to instantaneously compensate for image density variations due to fluctuations in toner concentration. A time-delay model of developer housing dynamics is maintained in machine software of a controller that approximates delay between toner concentration sensing and image development, delay caused by toner-carrier mixing, and/or delay caused by transport of toner-carrier from the development housing to the developer roll. The approximations can be adjusted according to actual measurements over the last several minutes of operation. The controller compares predicted toner concentration sensor signals with averaged actual toner concentration sensor signals to detect long-term and/or short-term drift. Based on the approximations and detected drift, the controller computes and transmits a feed forward correction signal to adjust electrostatic setpoints of an electrostatic controller on a print-by-print basis in order to compensate for fluctuations in toner.

Method and apparatus for dynamically controlling image density

In an electrostatic and development control in a printing apparatus, unwanted variation in dot size and shape may be stabilized and the DMA variability under halftone control may be decreased, by use of a novel halftone discharge ratio (HTDR,) along with the conventional actuators of development potential, cleaning potential, and exposure level. A three-input, three-output MIMO control system may be constructed to deliver superior regulation of halftone and solid area image quality with use of control algorithms that are based on the halftone discharge ratio and with use of as few as two developed halftone test patches.

Control of halftone and solid area image quality by way of a halftone discharge ratio

A method and apparatus in an electrostatographic reproduction machine having a plurality of development units for reliably producing high quality toner particle images under varying sustained area toner coverage conditions. The apparatus employing the method includes a control system (a) for reading a stored area toner coverage level threshold value; a first operating time control algorithm and a second operating time control algorithm for adding and admixing in each development unit of the plurality of development units; (b) for measuring sustained area toner coverage levels of images being reproduced during a reproduction job; (c) for comparing the measured sustained area toner coverage levels of images being reproduced with the stored area toner coverage level threshold value; and (d) for changing the operating time control algorithm for adding and admixing in each development unit between the first operating time control algorithm and the second operating time control algorithm depending on a result of comparing the measured sustained area toner coverage levels of images being reproduced with the stored threshold value.

Electrostatographic reproduction machine having dual mode development

Reload characteristics of a development member such as a donor roll are monitored by using a machine exposure system (ROS or LED Bar) to generate a test image composed of a short (in the process direction) high density solid area patch followed by a long mid and lower density areas (solid or halftone), the later corresponding to Reload Defect (RD) exhibited by the development member. Typical dimensions of the test image would be a 15 mm square high density patch followed by a 200.times.15 mm mid and lower density regions. This test image voltage profile is placed in a skipped image frame inserted into a long job, or is effected during cycle-out/down following a shorter job run, and is scheduled at infrequent periodic intervals, for example, every 2000 prints. The resultant developed toner pattern on the photoreceptor is monitored, for example, with a reflectance or transmission density sensor such as the Toner Area Coverage (TAC) sensor used in the 4700.TM., 4850.TM., and 5775.TM. imaging products or an Extended Toner Area Coverage (ETAC) sensor. The toner dispense rate is adjusted to obtain a desired level of Reload Defect in the developed toner patter which corresponds to the optimum level of Toner Concentration in the development system.

Signature sensing for optimum toner control with donor roll

A method of compensating for toner cohesivity within a repository in a developer system by recording toner consumption rate and toner dispense rate over a given time within the developer system. A control responds to the toner consumption and dispense rates over the given time period to compute toner residence time in the repository and estimate a degree of toner cohesiveness. The control then projects an adjustment to the development voltage to suppress the effects of toner cohesivity.

Adaptive feed forward compensation for time varying toner cohesivity

A printing system using a recharge, expose and development image on image process color system is disclosed in which there is an optional extra black development step. The printing system may be a single pass system where all of the colors are developed in a single pass or a multi-pass system where each color is developed in a separate pass. The additional black development step results in optimal color quality with black toner being developed in a first and/or last sequence. Having more than one black development station allows low gloss and high gloss black toner to be applied to the same image, enabling the very desirable combination of low gloss text and high gloss pictorials on the same page.

Image on image process color with two black development steps

A developer control for enabling the use of developer and toner materials with widely varying At in high quality xerographic copying and printing. Pixel count data is combined with toner test patch reflectance data during a brief toner rundown to determine the rate of change of density per unit change in toner concentration. During toner rundown, dispensing of toner is suspended for a period of time for effecting toner concentration reduction by approximately 0.25%. The change in Toner Concentration (TC) is estimated using pixel counting. Additionally, toner test patches are created and the reflectance thereof is measured for determining the change in toner density. The estimated TC change and the change in toner density are processed using linear regression to find the average change in density sensor output for the estimated change in TC which is referred to as the rundown slope. The rundown slope is then compared to a target value. If it exceeds the target value by more than ? (a noise factor), the dispense setpoint is reduced by one unit. If the rundown slope is less than the target value by more than ?, the dispense point is increased by one unit. The noise factor, ? is attributable to errors in pixel count or reflectance sensor drift. According to the foregoing, the nominal control line and control band in TC-Tribo space is altered to produce a much wider usable At range.

Closed-loop developability control in a xerographic copier or printer

An automatic xerographic set up and monitoring process for a multi-mode electrostatographic machine in which a corona charge intercept value is obtained and used to optimally set corona charging levels for different modes, optimum flash exposure levels obtained, ID lamp intensity correlated with flash exposure levels, and xerographic process parameters set for each different mode.

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Fairport, NY, United States of America

Robert E Grace