Abstract: An image processing apparatus including tandem print engines is provided for forming an image on an image receiving substrata. The apparatus includes a first print engine and a second print engine downstream from the first print engine. The second print engine is slaved to the first print engine. The first print engine has a first photoreceptor and a first period of revolution. The second print engine has a second photoreceptor and a second period of revolution. The image processing apparatus further includes an intermediate inverter that inverts the image receiving substrate between the first print engine and the second print engine. The inverter determines a phase difference between a first seam signal from the first photoreceptor and a second seam signal from the second photoreceptor.

Abstract: Drive train motor speed is varied in a manner that compensates for characteristic rotational velocity errors of the associated drive train, such as by modulating a drive train motor speed control signal at a modulation phase and amplitude derived from the characterized rotational velocity error. Characterization can be performed on a test system for each drive train of interest, and the compensation values thus obtained can be saved for later use by systems in which the characterized drive trains are used. Thus, a drive train used in a consumables cartridge for an electrophotographic printing (EP) system can be characterized and the corresponding data saved via a label or memory circuit that is affixed to the cartridge. Such data can be used by the EP system in which the cartridge is installed to more accurately control the velocity of the image forming process members driven by the cartridge's characterized drive train.

Abstract: A method of aligning a print image of an electrophotographic machine, the method including the steps of determining a power level of a laser beam, sensing a synch position of the laser beam associated with the scan line and varying a delay time before starting the scan line dependent upon the power level and the synch position.