Abstract: The tacking pressure and droplet acceleration force in an ink jet printer is provided by an array of electrodes mounted under the transport mechanism. The array consists of multiple pairs of oppositely charged electrodes and the array is maintained at a bias voltage while the print head of the printer is grounded.

Abstract: A copy machine having a high accuracy sheet registration system for precise placement of images on each copy sheet. The copy machine includes sensors with charge coupled devices (CCDs) that detect the sheet positions in two dimensions within the machine, and detect sheet arrival times at various positions with the machine. Using this detected information, the copy machine employs a multi-stage process to bring the sheet into contact with a color image moving on a photoreceptor belt, in synchronism with the position and speed of the image on the belt. The copy machine also monitors its own condition and makes predictions about needed preventive maintenance, to instruct personnel to service the machine before the machine fails.

Abstract: Systems and methods are provided that improve the registration between the color separation images. The systems and methods control the output of the image data for one or more of the color separation images and the velocity of an image-carrying member to remove or reduce registration offsets based on determined position and velocity of the image-carrying member. A position-determining sensor on an image-carrying member device module is used to determine the process-direction position of the image-carrying member to provide real time motion information. A position-determining controller determines the process-direction position of the image-carrying member by detecting a pattern of position-determining marks using the position-determining sensor and processing the detected data through averaging or correlation to eliminate detection errors.

Abstract: A tensioning mechanism is provided for minimizing tension variations in a moveable endless belt having a desired tension setting and includes a moveable member for mounting transversely to a direction of movement of the moveable endless belt and into contact with the moveable endless belt; a first assembly including a first rotatable arm having a first end connected to the moveable member, and a second end coupled to a first pivot; and a second assembly including a tensioning force applying roller, and a second rotatable arm having a first end connected to the moveable member and a second end coupled to a second pivot.

Abstract: A method and apparatus for periodically upgrading the color calibration for an electrophotographic printer (or other digital document viewing device) using a color compensator is proposed. Initially, a fairly large number of colors are printed and measured. From this information a color correction is determined and stored in a high density compensator. A small number of color patch samples are printed and measured at regular intervals during the use of the printing machine. This low density information which is periodically updated compensates for slow drift in the high density compensator. Each time the small patch printing process is repeated a different set of colors is used to assure that all regions within the gamut of the machine are updated uniformly. A similar process can be used to maintain the gray scale fidelity in a black and white printer or digital document display device.

Abstract: A droplet-on-demand ink jet printer uses electrostatic tacking of a recording medium, such as paper, to achieve simultaneously precise holding of an aligned recording medium on a dielectric surface of a transport belt, thereby providing precise motion quality of the recording medium relative to the printer's printhead, and improved ink droplet placement on the recording medium. The transport belt is electrostatically charged with a charge of one polarity, so that an electrostatic pressure is generated which precisely holds the recording medium in an aligned position on the transport belt, after it is fed thereon, and concurrently induces a charge of opposite polarity on the ink droplets ejected by the printhead, thereby accelerating the droplets toward the recording medium.

Abstract: A printing system including a moving intermediate transfer member for transporting a developed image from a moving image bearing member to a moving copy substrate. The moving intermediate member includes an elastic belt adapted to receive the developed image from the moving image bearing member at a first nip formed between the moving image bearing member and the moving intermediate member, and further adapted to transfer the developed image from the moving intermediate member to the moving copy substrate at a second nip formed between the moving intermediate member and the moving copy substrate, wherein the moving image bearing member and the moving intermediate member are transported at a substantiality equivalent first velocity in the first nip and a second velocity, substantially different from the first velocity, in the second nip.

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: This invention provides for duplex use of densitometers. An image is produced on a substrate, that substrate is brought back through the transfer station in a duplex fashion (that is, the substrate is inverted), and a sensor senses the image on the substrate. Beneficially, the sensor senses one or more parameters such as color registration, color occlusion/interference, black separation in color REaD printing, colorimetry, and the overall transfer and fusing process; and a printing process is controlled based on the sensed parameters.

Abstract: An apparatus and method for registering and deskewing a sheet along a paper path. A pair of independently driven selectively actuable nips are used to drive a sheet transverse to a paper path direction until the edge of a sheet is registered laterally and in skew. The transverse nips are then deactivated and a drive nip moves the sheet in a process direction along the paper path. A first transport sensor senses the lead edge of a sheet, a second sensor is used to also detect the lead edge of a sheet within a certain distance from the detection by the first sensor. The transport drive nip can then be adjusted based on the transport time between the first transport sensor and the second transport sensor so that the sheet arrives at a registration sensor at the prescribed time. This apparatus and method allows the use of simple point type sensors as opposed to more complex and expensive sensor arrays.

Abstract: A method and apparatus is provided for controlling the transverse registration of an image area to be exposed on a longitudinally moving belt by providing belt edge profile data, detecting a lateral position of the belt during movement of the belt by measuring the lateral position of the belt edge, and adjusting the transverse location of the image on the belt to compensate for a difference between the detected lateral belt edge position and the belt edge profile data. In addition, a method and apparatus is provided for controlling the lateral position of a longitudinally moving endless belt by generating a steering command signal by calculating a difference between the detected first lateral position of the belt edge and the belt edge profile data corresponding to the first longitudinal position, and adjusting the lateral position of the belt by steering the belt in response to the steering command.

Abstract: An apparatus for guiding a moving belt, 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 belt being of the type which is supported by a plurality of rolls. A compliant belt guide is positioned at each end of a tensioning roll. The guide is biased so as to absorb a portion of the force exerted on it by the moving belt but to maintain a minimal belt walk in a direction transverse to the predetermined path.

Abstract: A detection system includes a marking device for applying to a process medium a first chevron from a first printer, a second chevron from a second printer and a third chevron from both the first printer and the second printer, the third chevron having a first element applied from the first printer and a second element applied from the second printer. The detection system further includes a detection device for detecting a matrix of times including three pluralities of times, each of the three pluralities of times corresponding to a respective time of passage of the first, second and third chevrons by the detection device. The detection system further includes a determining device for determining the alignment error based on a function of the three pluralities of times. A control system includes a marking device for applying to a process medium a first chevron from a first printer, a second chevron from a second printer and a third chevron from both the first printer and the second printer.

Abstract: A color printing system achieves enhanced registration of a plurality of color separations. A plurality of color separation images are formed on a receptor in spaced relationship to one another, the distance between the leading edges of successive images corresponding to a pitch distance. The motion components of the system have circumferences which are equal to or a submultiple of the pitch distance. Any systematic errors due to motion of the components will repeat themselves identically for each color separation and eliminate misregistration.

Abstract: Low lateral force rolls used in supporting a photoreceptor belt to minimize lateral belt motion on a multi-pass color copier. Single piece, widely spaced mounting through shafts are used in connection with side support structure of the module drawer to reduce inboard and outboard misalignment. An integral tensions slide/side plate guidance control system is employed to reduce misalignment of the tension roller. Use of these features aid in minimizing undesirable belt movement.

Abstract: A belt receptor module for a color printer isolates disturbances such as impulsive and high-frequency force disturbances caused by entrance of a recording medium into a transfer nip of a transfer station. The belt receptor module includes a belt receptor positioned about a plurality of spaced rollers. A transfer station is located adjacent an area of the belt receptor. A tension roller is located adjacent the belt receptor on either side of the transfer station. The tension rollers each articulate about an appropriate axis to enable the belt receptor to enter a subsequent roller at angle of approximately 90.degree. to its axis without generating lateral forces. Each tension roller is movable along a different line to create a tension level therein, each tension level being different from the other tension level.

Abstract: A method and apparatus is disclosed for an improved liquid development system for a high speed reproducing machine having a movable image retention belt. The liquid development system comprising a moving belt applicator mounted on a drive assembly containing at least one drive roll and a low lateral force roll with a position guide. The belt applicator is located in alignment with the image retention belt and spaced therefrom to form a development zone having a uniform gap with an extended length. The applicator drive roll and a low lateral force roll are positoned to transport the belt applicator in the same or opposite direction as the image retention belt, but at a much faster speed to facilitate an evenly distributed flow of liquid developer and to avoid depletion of toner particles from the liquid developer moved through the development zone.

Abstract: A method and apparatus for synchronizing a transfer loop in a recirculating color printer includes two spaced pairs of pulleys having a conveyor belt positioned thereabout for conveying sheets to a transfer zone for image transfer and an external pair of idler pulleys. A gripper bar on the conveyor belt advances the sheet. A photoconductive drum includes a portion in the transfer zone. A corona generating device is located in the transfer zone to charge the sheet so that it will attract an image from the photoconductive drum. A motion control servo provides ground-referenced control of motion of the conveyor belt as the gripper bar is delivered to the transfer zone. In the transfer zone, control is shifted to a phase detector which maintains constant the initially sensed phase between idler pulleys and a photoconductive drum coaxial therewith.

Abstract: A flexible force transmitting member biasing arrangement consisting of a snubbing device and a spring. The arrangement functions to permit a flexible force transmitting member attached to it to undergo a significant amount of movement (due to the force exerted by the spring) at very slow rates but prevents the flexible force transmitting member from undergoing substantial movement at high rates attendant with high frequencies of motion. A preferred form of the snubbing device is a dashpot.