Abstract: A diagnostic routine for determining the cause of color non-uniformity in a full color image forming device, by selecting a substation of one print station and using it in combination with a substation from another print station, while functionally omitting the intervening substations. The charge setting on the charge substation is adjusted to compensate for the increased distance between the charge substation, and the developing substation in this method.

Abstract: An impending fault of a component operated within a closed-loop control system can be detected. The close-loop control system is disabled. An actuator of the closed-loop control system is operated at one or more test values. A sensor reading of the actuator is taken while that actuator is operated at the one or more test values. A warning is generated if an impending fault condition is detected. An impending fault condition may be detected if the component operates at a value exceeding a maximum defined operating value, if the component operates at a value below a minimum defined operating value, or if an operating range that is narrower than a defined full operating range for the component is detected.

Abstract: An impending fault of a component operated within a closed-loop control system can be detected. The close-loop control system is disabled. An actuator of the closed-loop control system is operated at one or more test values. A sensor reading of the actuator is taken while that actuator is operated at the one or more test values. A warning is generated if an impending fault condition is detected. An impending fault condition may be detected if the component operates at a value exceeding a maximum defined operating value, if the component operates at a value below a minimum defined operating value, or if an operating range that is narrower than a defined full operating range for the component is detected.

Abstract: A distributive pitch skipping method and apparatus for stabilizing productivity in an electrostatographic printing machine. The method and apparatus provide for establishing a first toner concentration (TC) limit at and below which toner image reproduction of the machine stops and the machine dead cycles; establishing a second TC limit, higher than the first TC limit, above which the toner image reproduction rate of the machine is 100% at ST ppm (Standard prints per minute); adding fresh toner into a developer housing of the machine in an attempt to maintain the TC of the developer housing above the second TC limit while running copies having various toner area coverage levels; and establishing at least a third TC limit, between the first TC limit and the second TC limit, above which the toner image reproduction rate is less than 100% at (ST-X1) ppm, and below which the toner image reproduction rate is less than 100% at (ST-X2) ppm, where X1 and X2 are integers, and X2 is greater than X1.

Abstract: An improved method and apparatus for predicting the end of life of a photoreceptor, first records sampled data, then processes the data in order to interpolate the photoreceptor's end of life. Increased prediction accuracy is realized since both global photoreceptor information concerning a population of photoreceptors as well as information directed to a specific photoreceptor operating under particular environmental conditions are taken into account. This information is used not only to predict photoreceptor end of life but to make adjustments in the printing machine to correct xerographic degradations. In one embodiment, the information is used to direct an embedded end of life predictions system for notifying service at a remote site of photoreceptor problems in the printing machine in such a manner that it is transparent to a user of the printing machine.

Abstract: An apparatus and method for maintaining a constant voltage potential on a photoconductive member within an electrophotographic printing system comprises and utilizes, respectively, a charging device, a voltage monitor and a controller. The charging device produces a voltage potential on a photoconductive member within the electrophotographic printing system. The voltage monitor measures the voltage on the photoconductive member and generates a voltage measured signal. The controller, responsive to the voltage measure signal, stores a target voltage value and computes the difference of the measured voltage signal and the target voltage value to obtain a voltage error for a prior print job. The controller computes a predicted control signal for the corresponding cycle of the next successive print job as a function of the voltage error and regulates the charging device for the corresponding cycle of the next successive print job as a function of the predicted control signal.