Abstract: An interlock/latch system for a machine cover, particularly for an electrophotographic printing machine. A cover latch is provided with a latching mechanism and a set of electrical contacts which are mechanically closed when the cover is closed and the latch engaged. A sensor such as a Hall-Effect sensor is mounted in close proximity to the latch. A magnet in the cover actuates the Hall-Effect sensor when the cover is closed and latched sending a signal to the machine controller. The machine controller prohibits operation of the machine until the signal is received.

Abstract: A cleaning apparatus having a spots cleaning blade to remove residual agglomerations of particles from the imaging surface. The spots cleaning blade is made from a material that has a low coefficient of friction, low resilience and higher hardness than a standard spots blade. These properties enable the spots cleaning blade to provide a continuous slidable contact with the imaging surface to remove residual particles therefrom. Additionally, an electrically conductive surface can be added to the front or back surface of the blade to cause toner particles to be repelled from and cloud near the blade where they can be removed by a vacuum device or the like. The conductive surface may be direct negative, direct positive or A-C potential to provide the necessary repelling force.

Abstract: A self adjusting jam prevention guide and jam clearance baffle for a printing machine. A moveable guide is attached to a machine subsystem module and is moveable from a first position to a second position. In the first position the guide bridges a gap between the machine subsystem module and a preceding subsystem module. In the second position, the guide is retracted from the gap to allow easy removal of one of the subsystem modules. The moveable guide is preferably self actuated by the use of a biasing device and a ramped section so that the movement of one of the adjacent subsystem modules causes extension and retraction of the guide. A jam clearance aid is further attached to the exit of the machine subsystem module. The clearance aid uses a J-shaped channel to cause a sheet fed into a jammed sheet to buckle and cause both the first jammed sheet and subsequent sheets to be partially ejected from the paper path for easy removal therefrom.

Abstract: A noncontact seal for a donor roll in an electrophotographic printing machine. The seal is fixed in the developer housing and envelopes each end of the donor roll but does not contact the donor roll. The small space does not allow a positive airflow sufficient to cause toner particles to be emited from the developer housing so as to contaminate the other portions of the printing machine. The seal is made of a low friction material such as DELRIN.RTM. so that toner particles do not stick to the seal and cause a buildup that would be detrimental to the photoreceptive member.

Abstract: An apparatus and method for eliminating random noise and calibrating a seam detection sensor in an electrophotographic printing machine. When the detected centerline remains within the tolerance window the algorithm proceeds as normal. In most cases, however, the center line is shifted outside the tolerance window., either from 2 to -X or +X to N-1. When the centerline falls within either of these two ranges, the algorithm recognizes this fact and assumes that a random noise condition has occurred. It then proceeds to take the previous centerline (C) and add the current photoreceptor belt length to it. This, theoretically, should be exactly where the centerline should have been in the absence of noise. If this condition continues for three successive belt revolutions and the machine completes the job it was running, the algorithm will force the machine to search for the seam at the next cycle up.

Abstract: A developer backer bar having a substantially flat surface for interfacing with a noncontact developer member. The backer bar is arranged so that it can be retracted for clearance purposes when removing or inserting a xerographic CRU. Upon installation of the CRU, the backer bar is biased into position to maintain a development zone within predetermined parameters. The substantially flat surface eliminates or minimizes errors that may result from slight variations in axial alignment between the backer bar and the developer member.

Abstract: A method to automatically adjust the timing of a process control toner patch reading in an electrophotographic printing machine. A solid area patch of width "X" is generated by the ROS at the time "T" from pitch reset. Theoretically, the centerline of this patch (X/2) should arrive at the BTAC location in a time of "T+distance from pitch reset to BTAC". A series of evenly spaced reads are taken by the BTAC of the solid area patch. This sampling generates a waveform. The area of this waveform is calculated and the center of moment is found This "real" centerline of the patch is then compared to the theoretical centerline and the delta (+or -) is stored in memory. This provides a read adjustment to maintain accurate process controls.

Abstract: A floating feedhead having a variable sheetpath for an electrophotographic printing machine. A feeder for feeding sheets from the top of a stack to a processor for a printing machine is disclosed. The feedhead is of a standard retard feed type having either a nudger roll/feed roll or a feed belt in combination with a retard member to separate sheets. The feedhead is connected to the sheet delivery area of the machine by a variable length, variable speed sheetpath. The sheetpath has a drive member such as a drive nip in cooperation with the feedhead. When the sheetpath is at its longest the feedhead and variable drive member operate at a higher speed to deliver the sheets to the sheet intake area at a predetermined time interval. As sheets are fed and the sheetpath becomes shorter, the variable drive and feedhead slow to maintain proper sheet timing. The sheetpath may be of a telescopic baffle configuration or could alternatively be a variable speed vertical transport arrangement.

Abstract: A paper conditioner to control image dependent curl which uses one or more counter-rotating transfer rollers which are initially spaced from their respective back-up rollers in the intercopy gap, and which come together as the lead edge enters the nip area, and separates when the trail edge is about to pass. This permits the rollers to have a less demanding runout tolerance by bringing the rollers together when the sheet is in the nip, and then articulating the rollers apart in the intercopy gap.

Abstract: An apparatus for developing an electrostatic latent image in a liquid developing material-based electrostatographic printing machine including a control system for controlling an amount of marking particles, carrier liquid and/or charge director added to a supply of liquid developing material utilized for developing a latent electrostatic image such that the concentration of marking particles and or charge director can be maintained at an optimal value. The amount of marking particles, carrier liquid and/or charge director in a supply of liquid developing material is maintained at a predetermined optimal value in response to the amount of marking particles and/or charge director depleted from the supply of liquid developing material with each development cycle. A supply reservoir is maintained with a substantially constant amount of liquid carrier to which is added marking particles and/or charge director to provide an operative solution of liquid developing material.

Abstract: A deskewing and registering device for an electrophotographic printing machine. A single sensor determines the position and skew of a sheet in a paper path and generate signals indicative thereof. A pair of independently driven nips forward the sheet to a registration position in skew and at the proper time based on signals from a controller which interprets the position signals and generates the motor control signals. An additional single sensor can be used at the registration position to provide feedback for updating the control signals as rolls wear or different substrates having different coefficients of friction are used.

Abstract: A hybrid jumping development system utilizing two component developer and providing an improved device for controlling developed toner mass. Toner is metered onto a donor structure and a toner cloud is formed in a development nip between the donor structure and the charge retentive surface having a latent electrostatic image thereon. The toner cloud is formed by applying an alternating potential to the donor structure so as to cause the toner particles to jump off of the donor structure. The duty cycle of the AC potential is used to control the toner cloud and thus the amount of toner developed on the charge retentive surface.

Abstract: A retaining device for a photoreceptive member in a xerographic CRU. The belt in a CRU is retained by the device and held in a shape so that it will slide easily over a drive module without catching on other machine components. The device is made up of a plurality of fingers that hold the belt in position during shipment and installation. Once the CRU is installed and an interlock handle turned, the belt is released from the fingers and is in an operative, supported position on the drive module. To remove the CRU, the interlock mechanism is reversed and the belt is again captured by the fingers and held in a shape to allow easy removal over the drive module.

Abstract: A method and apparatus for producing enhanced quality full color prints in an electrophotographic printing machine. In a electrophotographic printing machine in which multiple color separations are imaged and developed on a photoconductive member, a user selectable enhanced print mode is provided. In the enhanced print mode, each color separation is imaged and developed on the same imaging panel of the photoconductive member. This avoids a degradation in image quality due to physical variations and defects in the photoconductive member. The enhanced mode decreases machine productivity somewhat and is user selectable in situations when very high quality prints are desired.

Abstract: A method and apparatus for eliminating undesirable development of background charge potentials in a multicolor electrostatographic system is disclosed, wherein the application of a developer bias at a given development station is selectively controlled to be substantially equal to or greater than the background image voltage of the image generated by a preceding imaging station such that the voltage differential between toner particles at the development station and the background areas including the previous image areas is substantially zero and the electrostatic forces acting on the toner particles are insufficient to attract the toner particles to the residual image.

Abstract: A compact dual decurler mechanism that provides a single straight paper path for achieving bidirectional decurling capability. The dual decurler mechanism consists of two pairs of drive roll and pinch shaft and a camming mechanism for controlling their engagements. The first and the second pairs are oriented in opposite directions in a manner that they can selectively form opposite bending nips for decurling incoming sheets of different curl directions. The operation of the dual decurler can be software controlled through the use of an electric indexing clutch such that, depending on system inputs on image area coverage and the type of finishing device being used, the first pair can be adjusted for toward image (TI) bending, the second pair for away image (AI) bending, or both be set at a neutral setting that keeps both nips open when no decurling is needed. The architecture of the single straight paper path of the dual decurler can minimize paper jams and avoids potential damage to sheets.

Abstract: A modular fuser assembly having a lightweight plastic structural housing. The lightweight housing is made possible by utilizing heavy steel endplates which are designed so that the net moment on each end plate pair is minimized. This is accomplished by having the load points on opposite sides of the endplate and aligned such that the moments tend to negate each other. The design of the endplates allows the use of relatively lightweight cross members thus enabling the lightweight thermoplastic housing.

Abstract: A stack height control assembly utilizing the feedhead as the height sensing member. As a result of incorporating the stack height sensor into the feedhead, several advantages are realized. There is no additional drag imparted to the sheets as the result of a sensing arm or other sensing member. This also reduces the possibility of skewing the sheets with an additional sensing member. The feedhead, due to the normal force required to acquire the sheets also provides an accurate measurement of stack height. The normal force of the feedhead also eliminates and inaccuracies that could be caused by curled sheets in a feed tray. The stack height is also measured "on the fly" as the sheets are being acquired and fed, thus providing an efficient stack height sensing scheme. A floating coupler and sensor flag arrangement can be mounted so that it is engaged with a paper supply drawer as the drawer is moved into an operative position.

Abstract: A printing machine having multiple distributed high voltage power supplies is disclosed. The printing machine comprises a print engine having a plurality of high voltage electrical printing machine components. A housing supports at least one of the high voltage power supplies. A receptacle mounted on the housing receives an external connector from one of the machine components. The receptacle is fixed on the housing and is not detachable. A contact located inside the receptacle electrically connects circuitry from the power supply to the external connector. A second contact on the housing electrically connects circuitry from the power supply to a second external connector on the machine component.

Abstract: A lightweight easily installed shield for a corona generating device. A frame to support the end blocks and provide a structural member for a corona generating device is provided. The shield for the corona generating device is made of a lightweight, thin conductive material such as stainless steel and are formed so that they have a generally bowed out cross section prior to installation in the frame. To install the shield in the frame it is squeezed together and inserted in the frame. Once released the resilient bias of the steel causes the shield to be restrained within the frame and can be accurately located and retained by using a locating pin or ridge formed in the frame. The shield described allows easy and accurate assembly of the corona generating device.