Abstract: A digital color printing system having an input device such as a joystick is disclosed that provides real-time print quality control during a print run. The joystick is located near an output tray to enable an operator to perceive adjustments to print quality in real-time. The joystick modifies nominal electrostatic control points stored in non-volatile memory (NVM) of the printing system. Long term process controls are unchanged by joystick input, while short-term xerographic process controls are overridden by joystick commands. In one embodiment, joystick controls are used to adjust electrostatic controls which include adjusting developer bias and transfer current. In another embodiment, joystick controls also adjust, image processing parameters such as TRC curves. The new image processing parameters require that a contone image originally processed must be reprocessed to form a new raster image.

Abstract: Correction of image distortion in a reproduction machine due to vibrational or speed distortions in or between a moving photoreceptor and an imaging device projecting raster lines on the photoreceptor as it moves past the imaging device, utilizing in encoder for sensing the speed of the photoreceptor and also the relative vibrational motion between the photoreceptor and the imaging device and providing electrical signals to a signal separator separating the electrical signals into lower and higher frequency signals, and a servo motor for driving the photoreceptor and compensating for the lower frequency increases or decreases in the speed of the photoreceptor, the servo motor being driven by the separated lower frequency signals; and an optical system for pivoting the projected raster lines to compensate for the image distortions which are of the higher frequencies, the optical system being driven by the higher frequency signals from the signal separator.

Abstract: An optical imaging system for scanning a document moving through an exposure zone. The imaging system comprises optical components including a mirror arrangement and a projection assembly for projecting reflected document images onto a flat portion of a photoreceptor. The optical components are stationary in a first mode of operation wherein documents are stream fed past the exposure zone at the process speed. In a second mode of operation, wherein multiple copies are made of the same document, the optical components are moved in a defined relationship so that the image is projected onto the photoreceptor in a direction opposite to the direction of photoreceptor motion. This form of image projection is termed image precession and results in additional time being available to replace the document at the start of scan portion without reduction in copy reproduction rate.