Abstract: An electrophotographic printing machine is provided having an endless photoreceptor belt arranged to move in a predetermined path through a plurality of processing stations. The apparatus is used in conjunction with a method for automatically and repeatedly measuring and updating a steering coefficient used in an automatic steering mode. The method includes centering the belt and finding the average "in" belt walk and "in" belt walk rate and the average "out" belt walk and "out" belt walk rate, in order to determine the steering control coefficient. The method allows for a single machine to have its steering coefficient repeatedly updated.

Abstract: An automatic recovery apparatus reduces the number of shut downs due to fuser misstrips in an electrophoto-graphic device. A fuser misstrip occurs if the lead edge of a copy sheet does not emerge from the fuser nip. The fuser roller and the photoreceptor drive roller are stopped. These rollers are driven in the reverse direction until the copy sheet is released from the fuser. The rollers are then driven in the forward direction so that the copy sheet is re-fused. This automatic recovery apparatus is used for a photoreceptor misstrip. If the copy sheet remains attached to the photoreceptor belt after passing the stripping zone, it will jam in the cleaner module. If a sensor detects the copy sheet is still attached to the belt after the stripping zone, then the photoreceptor belt is reversed and the stripping procedure is repeated.

Abstract: An apparatus to detect sheet misfeeds and jams in an electrophotographic printing machine by measuring the tangential reaction force of a sheet entering the nip between two drive rolls and comparing the measured force with preprogrammed parameters within the machine controller. In the event the force measured does not fall within the programmed parameters, the drive motor controller and machine controller can take appropriate corrective action to display an error message, lessen sheet damage and prevent machine damage. A force library can be compiled to predict drive roll wear and failure so as to allow preventative measures to be taken.

Abstract: An image bar recording system, which, in a preferred embodiment, utilizes a plurality of LED image bars, forms a plurality of latent images, which may subsequently be developed in different colors. The print bars are initially aligned so that each color image is in precise lateral registration on the surface of a photoreceptor belt. The registration is accomplished by first forming a Z-shaped pattern along the non-image edge of a photoreceptor belt, the pattern extending in the direction of the belt motion (process direction). Each print bar is positioned adjacent the belt surface and the pixels of the LED array are selectively energized to form the desired image. An array of non-imaging pixels is contiguous to the image-forming pixels and positioned along the belt so as to be periodically visible through the Z-shaped pattern by photosensors positioned beneath each of the print bars.

Abstract: A method for controlling lateral positioning of a longitudinally moving endless belt having at least two targets aligned with tolerances on a longitudinal fixed reference line, in which belt displacement from the fixed reference line is measured at least two times during each revolution of belt movement to provide a current value of measured displacement and at least one prior value of measured. The current value of measured displacement and the at least one prior value of measured displacement are averaged to provide a current average value of measured displacement and a current average value of measured displacement is calculated for each successive current value of measured displacement to provide a belt steering correction factor used to steer the belt as necessary to reduce the current average value of measured displacement to zero. Each of the targets is preferably an apertured pattern of N-shaped configuration formed in the belt.

Abstract: An apparatus to bilaterally register and deskew sheets in an electrophotographic printing machine by driving the sheet against a pair of stalled drive rolls and then activating the drive rolls when the sheet is deskewed. The drive rolls are then laterally translated while the sheet is within the nips of the drive rolls. The proper side registration position of the sheet is sensed and stored and the sheet is brought to that proper registration position. Once the sheet has passed through the drive rolls, the rolls return to the center of the paper path to receive subsequent sheets. A stepper motor is used to translate the roll pairs in a lateral direction and the pulse counts are utilized to store the side registration and sheet acquisition positions thereby eliminating the need for a home position sensor or switch.

Abstract: A method and apparatus for transverse registration of image exposures on photoreceptive belts subject to lateral deviation from linear travel in which targets, corresponding in location to the image areas to be exposed, are used for the detection of lateral belt displacement and to control the transverse location of exposure scan. The targets are of a pattern defining a reference line and a line inclined with respect to the direction of belt travel so that the duration of time between passage of the target lines with respect to a spacially fixed sensing axis will vary with lateral displacement of the belt. The targets may assume a variety of specific patterns and the invention is applicable to single and multi-pass image exposure systems as well as to both modulated laser and light emitting diode types of exposure devices.

Abstract: A non-contact, transmissive energy sensor is utilized for determining the thickness of paper sheets in a feed path. The sensor includes an energy emitting source and an energy detector, the output of the energy detecting source being proportional to the amount of energy received by the energy detector. The signal output level of the detector is utilized in a model to determine the basis weight of paper in the detecting zone of the detector. Heuristic sampling techniques can be utilized to reduce or eliminate the effects of images printed on the paper and flutter of the paper as it moves. An automatic calibration routine utilizing boundary coefficients is used to calibrate the paper basis weight detection system. The paper basis weight determination is utilized to control subsequent operations to which the paper sheet is subjected in order to optimize image quality and sheet handling, and to control finishing operations.

Abstract: An optical scanning and illumination arrangement is provided for a document reproduction machine which includes a plurality of linear motors to drive the moving scan/illumination carriages. Each linear motor is under the control of a digital control circuit which, in turn, is under the control of a supervising circuit which maintains the status of machine operation and generates appropriate signals to control the individual digital control circuits.

Abstract: In xerography, registration method and apparatus for a variable pitch copier. The invention has particular utility in achieving a speed and position match between a copy sheet and an image on a photoconductor as the copy sheet approaches an image transfer station. According to the invention the speed and position of both image and copy sheet are monitored and updated by a programmed microprocessor. Controlled accelerations and brakings of a copy sheet drive motor under microprocessor control first achieve registration and then maintain that registration as the image transfer occurs. The disclosed registration automatically adjusts for variable spacings between successive images about the periphery of the photoconductor to accommodate various image sizes.