Abstract: An apparatus and technique to guide a fabric conveyor belt by alignment of the fabric weaves with a mating fabric on a vacuum platen is described. The technique functions in a manner similar to an edge guide, however the correcting forces are applied over the surface of the belt as opposed to the edge of the belt. Robust tracking can be achieved and the need for frequent adjustments of the conveyor rollers by the user is eliminated.

Abstract: A sheet aligning and registration device for a printing machine. In a stalled roll registration device there is provided a drive mechanism preceding the stalled roll which allows a sheet to move while within the drive nip. The drive mechanism uses a drive roll and an eccentric idler roll in contact therewith. The idler is biased against the drive roll by a compression spring such that as the eccentric idler roll rotates, the spring is alternately compressed and relaxed. When a sheet is driven through the drive mechanism and into the stalled nip, a buckle is formed which causes a force to be exerted on the drive nip which causes the eccentric roll to stall in the horizontal position in which little normal force is exerted on the sheet. The sheet is then free to deskew and align in the stalled nip. Once the sheet is aligned and deskewed, the stalled nip is actuated and the sheet is forwarded to a process station.

Abstract: An apparatus and method of developing a heat developing film includes a film support surface for supporting and constraining a film and heaters for developing the film supported on the film constraining surface. The film constraining surface may either be stationary or form part of a film transport. The film transport may either be a continuous film transport or a reciprocating film transport. The continuous film transport may be inclined or include an input pinch roller. In addition, the heaters may either be stationary, reciprocatable, or pivotable. The heaters are radiant heaters which may include a profiled heater output to control uniformity of the temperature. The apparatus may be provided as a stand-alone unit or may be coupled, either externally to or within, a film exposure device.

Abstract: A method of achieving optimum optical contrast for detecting registration marks in a multicolor electrophotographic printing machine. The reflectivity of the image carrying member which is usually an intermediate transfer belt is determined. The reflectivity of each of the toners is then determined. If one of the toners has a contrasting reflectivity, while the remaining toners do not contrast then a uniform field of the contrasting toner is imaged and developed and the registration marks for the other toner colors are then developed on top of the uniform field. A void in the field in the shape of the other toner marks is used as the registration mark for the contrasting toner. If all of the toners have a contrasting reflectivity with the belt, the registration marks are imaged and developed directly on the belt.

Abstract: A solenoid-controlled sheet registration mechanism for a copier/printer includes registration fingers for registering the lead edge of a sheet before it is fed to the transfer station of the copier/printer, to receive a developed image from the photoreceptor. The mechanism also includes a pair of nip rolls for forwarding the sheet to the transfer station, after registration. Energization of the solenoid moves the registration fingers into the registration position and disengages the nip rolls. Conversely, release of the solenoid allows the registration fingers to return to a non-registration position and the nip rolls to return to paper-feeding engagement, both of those return movements taking place under a resilient bias. To soften the impact between the nip rolls as they re-engage, and so reduce any resulting noise, the release of the solenoid is controlled by applying a pulsed drive signal to the solenoid during the release period after the energizing signal has ceased.

Abstract: An apparatus for fusing images to a sheet. A fuser device is provided using a transparent fusing roll having an internal heating device which focuses the energy to a narrow area of the roll adjacent the nip formed with a pressure roll. A transparent fuser roll is used in a pressure nip fusing system to take advantage of the quick response of a focused lamp system while at the same time yielding the desirable image quality attributes of the pressure nip in two roll fusing. The focused lamp is completely enclosed and the heated region of the paper is within the nip contact region so there exists no possibility of igniting the paper. A lateral temperature smoothing device, or leveling roll, is also provided to maintain a fairly uniform temperature axially across the fuser roll. This is particularly useful for a wide fuser roll, i.e., 17 inches, through which narrower paper, i.e., 11 or 14 inches, is passing to prevent the ends of the fuser roll which do not contact the paper from overheating.

Abstract: An idler system that is both self-centering and self-aligning with a drive roll. The idler assembly consists of a pair of rolls connected by a shaft, the shaft being supported in a housing. The housing is retained by a resilient spring member which member allows the axis of rotation of the idler rolls to pivot in more than one plane simultaneously. This pivoting causes the axis of rotation of the idler assembly to align parallel with the drive roll axis. The single spring also provides an even loading of the normal force across the width of the drive nip. As a result of the alignment and even loading, skewing of a sheet is prevented as it is driven through the nip formed by the drive roll and the idler roll. The resilient spring mounting also allows for easy replaceability of the idler assembly and the housing is easily locatable between tabs formed in the frame of the machine for mounting the idler assembly therein.

Abstract: An apparatus for controlling the concentration of toner within a developer material of carrier and toner. The apparatus having a magnetic roll for transporting a combination of carrier material and toner particles, a donor roll for transporting toner particles from said magnetic roll to a photoreceptor transfer zone, the magnetic roll and the donor roll each having a voltage applied thereto. A sensor measures the dynamic current between the magnetic roll and the donor roll and generates a signal as a function thereof. The dynamic current between the magnetic roll and the donor roll is a function of the concentration of the toner particles and the carrier material. As a result of the sensor output signal toner particles are added to the developer sump to maintain proper triboelectric properties within the developer unit.

Abstract: An apparatus for determining the dimensions of a stack of sheets in the tray. An optical sensor is arranged so that movement of the sheet guides in a paper tray causes a variably graduated scale to be moved past the sensor. The sensor may either be a transmissive or reflective type analog sensor in which the strength of the signal generated by the sensor is converted into a position of the side guides and as the analog scale is continuously variable, there is no need for separate discrete sensors or switches and sheet sizes of any dimension can be accommodated. A recalibration process is used to prevent contamination of the gauge and the associated change in signal strength by this sensor from causing the size determinations to be inaccurate. Alternatively, a digital sensor in cooperation with a digital bar code or other digital scale can be utilized to determine the variable sheet size, which digital sensor and variable scale are insensitive to contamination by dirt or paper particles, etc.

Abstract: A method and apparatus for minimizing image smear. A plurality of sheets are printed, each having the same test pattern thereon but varying a sheet transport speed as each sheet is printed. The sheets are then scanned by the machine and a velocity profile for each sheet is created. The velocity profile is then used to determine a standard deviation and a mean velocity which are then calculated and stored or can be plotted for each sheet. The point at which the relationship between the standard deviation and the mean results in the lowest value is the optimum speed for the subsystem being calibrated. The test is then performed on a second subsystem and repeated several times so that the optimum speeds for the pre and post transfer drives are quickly and easily determined.

Abstract: A method and apparatus for achieving optimum optical contrast for detecting registration marks in a multicolor print black first color electrophotographic printing machine. A black mask having voids in the shape of a registration mark is formed on the photoreceptor. A high contrast color is then overwritten on the mask forming marks which indicate the position of the black image. A second method utilizes only the first recharge unit and the last developer unit. A registration mark is imaged by each imager and all of the latent image registration marks are developed with a single color high contrast toner. A sensor is then used to determine the relative position of the various color imagers and to send signals to the controller to make appropriate corrections.

Abstract: An apparatus for adaptive localized sheet decurling in an electrophotographic printing machine. A segmented decurling device forms a drive nip with an elastically deformable surfaced roll. A plurality of sensors are provided to determine the basis weight of the copy sheet, the density of the image being transferred to the copy sheet and fused thereon, the relative humidity of the machine environment, the process speed of the print engine, and any other relevant parameters. Signals indicative of these parameters are generated and sent to the machine controller which processes these signals to determine the degree of curl expected in a sheet. Based on the degree of of curl for each sheet section corresponding to a decurler segment, the decurler segment is actuated to a setting which should provide the proper amount of mechanical decurling force. Each segment is activated only for the duration deemed necessary to decurl the imaged sheet portion corresponding thereto.

Abstract: An apparatus and method for controlling lateral movement of a belt supported on two or more rollers in an electrophotographic printing machine. The belt is rotated for several revolutions and the actual profile of the belt edge is sensed and stored. A steering roll is then tilted at an angle large enough to overcome any steering system backlash and the belt drift rate is measured. Incremental steering adjustments are then made in the opposite direction until the belt drift rate reverses direction. The steering system backlash is then determined as a function of the incremental angle (which is a known number of steering motor steps) and the number of corrective steering changes made. The backlash for the system in the opposite direction is then determined in the same manner. Steering corrections to the belt are then made with compensation for backlash so that the steering system is more responsive.

Abstract: A plain flanged bearing or bushing for supporting a rotating shaft in a thin walled frame of an electrophotographic printing machine. The composite bearing has a flanged end and is adapted to be inserted in an opening in a thin walled support member until the flange abuts the surface of the wall. A protruding tab formed by displacing a small portion of the flange extends in an axial direction along the bearing and cooperates with a corresponding opening in the wall to prevent rotation of the bearing. A friction push nut or snap ring is attached to the bearing on the side of the wall opposite the flange. The protruding tab prevents the bearing from rotating about an axis which can cause the bearing to be worn on the exterior surface by rotational contact with the thin wall. A shaft to support idler rolls or other rotating elements is inserted in an inner bore of the bearing and is rotatably supported thereby.

Abstract: A method and apparatus for controlling speed match between a photoreceptor and an intermediate transfer member to prevent image degradation by creating a deliberate speed mismatch. It has been found that slight variations in speed match between a photoreceptor and transfer member will maintain acceptable image quality, however, should the relative velocity between the members change sign, unacceptable image error results. The method herein comprises slewing the velocity of a photoreceptive member over a range of speeds while monitoring the output control signal current of a drive motor. The resulting control signal current has a large oscillation at the velocity at which the speed of the photoreceptor matches that of the intermediate transfer member. A controller is then used to maintain the motor velocity at a speed slightly less than or slightly greater than the intermediate transfer member speed so as to prevent a change in sign of the relative velocity between the two moving surfaces.

Abstract: A drive mechanism including a toothed pulley and a device for retaining mesh between the teeth of the pulley and the teeth of a belt after assembly thereto. The retaining device includes a retaining member positioned adjacent a toothed section of the pulley defining a space therebetween enabling the belt to fit between the retaining member and the toothed section of the pulley when the teeth are in mesh, the space between an apex or crown of a pulley tooth and the surface of the retaining member opposite thereto being smaller than the maximum thickness of the toothed belt thereby ensuring a mesh between the teeth of the belt and pulley to provide a synchronized drive therebetween.

Abstract: An apparatus for stacking, registering and attaching one or multiple sets of electrophotographic printing machine output. The copy sheets are discharged from the machine and fall into an inclined compiling tray and are longitudinally registered by flexible, endless belts contacting the top surface of each sheet. The belts are restrained from deforming and walking along the top of the stack by an idler member allowing greater stack capacity in the tray. Each sheet is then laterally shifted by a tamping mechanism to laterally register the sheet. Once a complete set of sheets has been discharged and fully registered the sheets of the stack are then attached by a stapler or some other sheet fastening or binding device and the stock is discharged from the compiling tray.

Abstract: A duplex path loop having a acceleration nip cooperating with a belt transport and retime nip to allow duplexing of sheets while minimizing skipped pitches on the photoreceptor. As each sheet to be duplex printed is removed from the process path after first side imaging it is accelerated to create a gap between it and subsequent sheets. The sheet is then stalled or slowed in a retime nip, while subsequent sheets to be duplexed are simultaneously driven by the same transport, the first mentioned sheet being reinserted into the process path at the proper time for receiving the second side image before the arrival of the second sheet at the retime nip. Subsequent duplex sheets are handled in the same manner so that duplex copies are interleaved or otherwise reinserted into the process path with first side copies so that skipped pitches on the photoreceptor are minimized.

Abstract: An apparatus for steering a moving web, particularly in an electrophotographic printing machine of the type having an endless photoreceptor belt supported by a plurality of rolls and arranged to move in a predetermined path through a plurality of processing stations disposed therealong the web being of the type which is supported by a plurality of rolls. A web steering roll for supporting the web being adapted for rotational movement about a first axis and tilting movement about a second axis transverse to the first axis is used.

Abstract: An adaptive cleaner blade lubricating system for electrophotographic printing machines. In an electrophotographic printing machine, the amount of residual toner available to lubricate a cleaner blade is calculated based on the density of the transferred image. A band of toner is deposited in an inner document gap in selective widths so as to provide an adequate amount of toner to lubricate the cleaner blade across the full width of the photoreceptor. The lubricating band may be variable or may be a constant width with the frequency of placement of the band determined based on average image density for a group of documents. In the preferred embodiment, the width of the toner band is varied as a function of the overall residual toner in each pixel location across the width of the photoreceptor based on the density of the images transferred. As a result of the varying lubrication bands, the cleaner blade is maintained so as to not tuck and cause streaking and/or damage while toner efficiency is maximized.