Abstract: An apparatus which advances sheets from different stacks of sheets. In one mode of operation, two stacks of sheets are supported side by side. A sheet feeder associated with each stack of sheets advances successive uppermost sheets from the respective stack to a transfer station of a printing machine. Alternatively, a single sheet feeder mounted movably in the sheet feeding apparatus may be employed to advance successive sheets from each of the stack of sheets, in lieu two sheet feeders. In the absence of these stacks of sheets, another oversized stack of sheets may be positioned in the sheet feeder. This oversized stack of sheets extends from a first sheet storing section into a second sheet storing section. When two stacks of sheets are disposed in the sheet feeder, one stack is positioned in the first sheet storing section and the other stack is positioned in the second sheet storing section. In this way, the sheet feeding apparatus has capability of feeding multiple size sheets.

Abstract: An apparatus for registering a sheet with a developed image on a moving surface. The apparatus includes a transfer station, detector, memory, and a registration transport. The detector is located at the transfer station and generates a registration signal in response to a sheet edge and a registration portion of the developed image. The memory stores sheet position factors and responds to the detector to update the factors. The registration transport communicates with the detector and the memory to move the sheet to the transfer station in registration with the developed image.

Abstract: A method and apparatus for identifying surface relief features of a substrate processed in a printing machine, and adjusting the machine parameters as a function thereof, before the substrate is processed through the machine. The apparatus includes a light source positioned adjacent to the substrate surface. A light sensing device, in a light receiving relationship with the substrate surface, detects light reflected from the substrate surface. A signal is generated indicative of sensed light intensity with a first magnitude range indicating ridges and a second magnitude range indicating depressions. Control circuitry, electrically connected to the light sensing device, receives the signals of ridges and depressions, and discriminates between them to generate a set of signals indicating surface relief features of the substrate.

Abstract: A solid area process control for scavengeless development using a transport roll-to-donor roll DC bias as a control parameter in an electrophotographic printing machine is disclosed. The process develops a latent image of a solid area toner patch on a photoconductive belt. Once the patch is developed, the patch is measured with an infrared reflectance type sensor. The measured development mass is compared to a target value stored in the machine memory. A test of the comparison is performed by the process. If the result of the test is less than the target value, the transport roll-to-donor roll bias is increased and the process ends. If the result is more than the target value, the transport roll-to-donor roll bias is decreased and the process ends, otherwise the process stops because the measured development is acceptable. The process is run at predetermined intervals to maintain constant output from the electrophotographic printing machine.

Abstract: An apparatus in which sheet basis weight is determined as a function of a change in angular velocity of a roller defining a nip through which the sheet passes. The sheet basis weight is calculated in response to the change in angular velocity of the roll before and after the sheet enters the nip. In an electrophotographic printing machine, the change in angular velocity of the fuser roll or pressure roll may be used to calculate the sheet basis weight.

Abstract: An electrophotographic printing machine of the type in which a leading edge and a trailing edge of a moving sheet are detected. The improvement includes an elongated light source that is of a length greater than that of an irregularity on the moving sheet. The elongated light source extends in a direction substantially parallel to the direction of the moving sheet. A plurality of sensors are arranged in an array and are movably mounted on a support which is extended in a direction substantially parallel to the elongated light source. The elongated light source is movably mounted to another support, so as to position the light source relative to the array of sensors. A lens, interposed between the light source and the sensor array focuses light rays emitted from the light source on to the sensors. The sensors are in a receiving relationship with the light source. The elongated light source and the array of sensors define a passageway through which the moving sheet passes.

Abstract: A multicolor electrophotographic printing machine employing a plurality of developer units. Each of the developer units is actuated to develop a selected latent image with the appropriately colored toner particles. The other developer units are de-energized. In the development mode, the electrode wires and the donor roll are electrically biased to suitable voltages. In the non-development mode, the electrode wires have only a DC voltage applied thereon with the AC voltage being turned off. Substantially, simultaneously therewith, the electrical bias on the donor roll is adjusted to prevent further development. In this way, the developer unit does not develop a latent image in the non-operable mode and does not attract toner particles thereto from the latent image.

Abstract: An apparatus in which an advancing copy sheet is disclosed. The apparatus includes a moving imaging member having a toner image thereon. The copy sheet contacts an imaging member to transfer a toner image from the imaging member to the copy sheet. A fusing member fuses the toner image to the copy sheet and advances the copy sheet at an adjustable velocity while the copy sheet receives the toner image from the imaging member. A controller communicates with the imaging member and the fusing member to maintain the velocity of the copy sheet with that of the imaging member. The velocity is maintained at a selected relationship. An imaging member drive moves the imaging member at a first velocity. The imaging member drive includes: a crystal clock that generates a fixed reference signal, a programmable divider which receives the signal and generates a control signal, and a servo motor responsive to the control signal. A fuser drive rotates the fuser roll to advance the sheet at a second velocity.

Abstract: An electrophotographic printing machine in which an electrostatic latent image recorded on a photoconductive member is developed with a liquid developer material. The liquid developer material is advanced by a substantially smooth donor roll from a supply to the latent image at a development zone. The liquid developer material on the donor roll is maintained at a thickness ranging from about 3 microns to about 10 microns.

Abstract: An apparatus for advancing a sheet from a moving imaging member having an unfused image after transfer of the image to the sheet. After the image is transferred to the sheet, the sheet is advanced by a transport to a fuser. The transport has low impedance, high air flow to draw the sheet toward the transport for acquisition. As the sheet is moved across the transport, an increased air flow impedance causes a low vacuum pressure in the transport to provide a low drive force that minimizes quality and motion disturbances on the sheet. The low drive force exerted on the sleet is lower than a holding force of the sheet to the moving imaging member thus causing the sheet to slide on the transport.

Abstract: An apparatus which separates and advances successive individual sheets from a stack of sheets. The stack of sheets is supported on a tray which moves in upwardly direction to position the uppermost sheet in engagement with an endless belt. The endless belt moves in a recirculating path to advance successive sheets from the stack. A retard roller engages the endless belt to define a nip for separating any overlapped sheets. Interposed between the retard roller and the tray is a stationary guide member. As the sheet advances toward the nip from the stack, it engages the guide member and is guided toward the nip. A thin, flexible member has one end secured to the guide member. The other end of the flexible member is free and extends into the nip. The flexible member is interposed between the belt and the retard roller with the sheet passing between the belt and the flexible member into the nip.

Abstract: An apparatus for advancing a copy sheet includes a moving imaging member having an unfused toner image. The copy sheet is in contact with the moving imaging member to transfer the toner image from the imaging member to the copy sheet. The copy sheet is then engaged by a moving sheet transport. A vacuum draws the copy sheet toward the sheet transport while a pressure sensor detects the vacuum pressure in the transport to control the air flow through the transport so as to maintain a low and constant drive force in response to the level of vacuum sensed by the sensor. The low drive force exerted on the sheet is lower than a holding force of the sheet to the moving imaging member thus causing the sheet to slide on the transport.

Abstract: An apparatus in which a donor roll advances toner to an electrostatic latent image recorded on a photoconductive member. A plurality of electrode wires are positioned in the space between the donor roll and the photoconductive member. The electrode wires extend in a transverse direction relative to the longitudinal axis of the donor roll. The electrode wires are electrically biased to detach the toner from the donor roll so as to form a toner cloud in the space between the electrode wires and photoconductive members. Detached toner from the toner cloud develops the latent image. Electrode wires contact a portion of the surface of the donor roll. As the donor roll rotates, friction between the electrode wires and donor roll causes trapped debris to move away from the toner powder cloud region so as to minimize contamination produced streaks on the developed image.

Abstract: A printing machine in which a recording medium has a latent image recorded thereon. A housing stores a supply of liquid developer material therein. The housing is operatively associated with a donor member for substantially uniformly coating liquid developer material thereon. The donor member is spaced from the recording medium. As the donor member moves, it transports the developer material to a development zone wherein the latent image recorded on the recording medium attracts at least the toner thereto to form a developed image thereon. A multicolor image may be formed by repeating this process for different developer materials.

Abstract: An apparatus in which toner fines are recovered from a recirculating liquid transporting toner pellets cut from extruded toner. The recirculating liquid cleans the pellet cutter and forms a mixture of liquid and toner fines. The recovery unit is positioned between the pellet cutter and a station discharging the pellets. In this way, clean liquid flows into the pellet cutter during each cycle. The recovery unit has a housing defining a chamber having two sections. A sloping screen is located in the chamber covering one of the chamber sections. The mixture of toner fines and liquid is dispensed onto the screen. The liquid passes through the screen and is recirculated. Toner fines collect on the screen. A backwash system washes the toner fines from the screen into the other section of the chamber. The mixture of toner fines and liquid is pumped from the other chamber section into a separator. The toner fines are separated from the liquid and re-used in the extruder.

Abstract: An apparatus in which an electrostatic latent image recorded on a photoconductive member is developed with toner. A donor roll, spaced from the photoconductive member, transports toner to a development zone adjacent the photoconductive member. An electrode member is positioned in the development zone between the photoconductive member and the donor roll. The electrode member is electrically biased to detach toner from the donor roll so as to form a toner powder cloud in the space between the electrode member and the photoconductive member. A unitary magnetic roll is located in the housing to transport developer material to a reload zone where toner particles are attracted from magnetic carrier granules to the donor roll. The parameters are selected to optimize reload and suppress strobe lines.

Abstract: An apparatus in which an electrostatic latent image is developed with liquid toner. The apparatus has a liquid extruder that extrudes a thin film of liquid toner which is attracted to the electrostatic latent image forming a liquid image on a photoconductive surface. The extruder is electrically biased to a suitable magnitude and polarity to ensure that the liquid toner is attracted to the latent image. A vacuum is applied on the liquid toner as it is being attracted to the latent image so as to reduce the thickness of the layer coated thereon.

Abstract: An apparatus which develops a latent image recorded on an image receiving member with developer material. A donor roll is positioned in a chamber of a housing having a supply of developer material. The donor roll transports a metered layer of developer material into contact with the latent image to develop the latent image. A conductive brush includes bristles having a diameter from about 6 to about 20 microns and contacts the metered layer of developer material on the developer roll. This substantially prevents the variation of triboelectric charge on the developer material on the donor roll so as to create a uniform charge level on the development material layer for development of the latent image.

Abstract: A single pass tandem architecture electrophotographic printing machine in which a photoconductive belt is supported by a plurality of spaced, stationary and arcuate members for transferring each color image from the photoconductive belt in registration with one another and having minimum registration errors from mechanical apparatus. Each of the latent images recorded on the photoreceptor belt is developed with different color developer material. The different color developed images are transferred from the photoconductive belt to a sheet of support material in superimposed registration with one another to print the desired multicolor information thereon.

Abstract: An apparatus which advances and separates sheets from a stack of sheets. The apparatus includes an operator pivotable frame having a nudger roll and a feed roll mounted thereon. In operation, the feed roll engages a retard roll. The retard roll is coupled through a gear to a slip clutch. In the event a single sheet is advanced by the nudger roll to the nip defined by the feed roll and retard roll, the frictional force between the sheet and retard roll is sufficient to overcome the torque applied on the retard roll by the slip clutch and the retard roll rotates in one direction permitting the sheet to pass through the nip. Alternatively, in the event multiple sheets are being advanced by the nudger roll into the nip, the frictional force is reduced and the retard roll rotates in the opposite direction under the torque applied thereon by the slip clutch driving the sheets back toward the stack from which they originally advanced.