Abstract: Devices include electrically conductive elements contacting a vacuum belt, and a voltage source connected to the electrically conductive elements. The electrically conductive elements form an electrical circuit from the voltage source, through the belt, and back to the voltage source. The electrically conductive elements are positioned so that they are separated from the belt when the belt moves the sheets of media between the electrically conductive elements and the belt. A processor is capable of identifying leading edges of the sheets of media on the belt (when voltage of the electrical circuit changes from a relatively higher voltage to a relatively lower voltage) and identifying trailing edges of the sheets of media on the belt (when the voltage of the electrical circuit changes from the relatively lower voltage back to the relatively higher voltage).

Abstract: An inlet seal, an outlet seal, and a piston are connected to a shaft. The inlet seal seals an ink inlet of an ink reservoir. The outlet seal seals an ink outlet of the ink reservoir. Also, the piston is within a cylinder. The inlet seal, the outlet seal, and the piston all move with the shaft. A biasing member contacts the piston to bias the piston in a first direction. Pressurized air simultaneously provided to the cylinder and to the ink reservoir biases the piston in a second direction, opposite the first direction, and pressurizes ink within the ink reservoir. Moving the shaft in the first direction does not seal the ink inlet but does seal the ink outlet. Moving the shaft in the second direction seals the ink inlet but does not seal the ink outlet, thus allowing the pressurized ink out from the ink reservoir.

Abstract: An inlet seal, an outlet seal, and a piston are connected to a shaft. The inlet seal seals an ink inlet of an ink reservoir. The outlet seal seals an ink outlet of the ink reservoir. Also, the piston is within a cylinder. The inlet seal, the outlet seal, and the piston all move with the shaft. A biasing member contacts the piston to bias the piston in a first direction. Pressurized air simultaneously provided to the cylinder and to the ink reservoir biases the piston in a second direction, opposite the first direction, and pressurizes ink within the ink reservoir. Moving the shaft in the first direction does not seal the ink inlet but does seal the ink outlet. Moving the shaft in the second direction seals the ink inlet but does not seal the ink outlet, thus allowing the pressurized ink out from the ink reservoir.

Abstract: A capping station is configured for storing printheads during printer inactivity to preserve the viscosity of the ink in the nozzles of the printheads. Each capping station has a receptacle, a vacuum source, a transducer, and a valve in an opening in a floor of the receptacle. A controller is operatively connected to actuators to move the receptacle so a seal on an upper wall of the receptacle engages a printhead housing. The controller also operates the valve to close the opening in the receptacle floor and then operates the vacuum source to establish a negative pressure in the volume within the receptacle. The transducer is then operated by the controller to fluctuate ink menisci in the nozzles of the printheads to prevent the ink from drying in the nozzles.

Abstract: A capping station is configured for storing printheads during printer inactivity to preserve the viscosity of the ink in the nozzles of the printheads. Each capping station has a receptacle, a vacuum source, a transducer, and a valve in an opening in a floor of the receptacle. A controller is operatively connected to actuators to move the receptacle so a seal on an upper wall of the receptacle engages a printhead housing. The controller also operates the valve to close the opening in the receptacle floor and then operates the vacuum source to establish a negative pressure in the volume within the receptacle. The transducer is then operated by the controller to fluctuate ink menisci in the nozzles of the printheads to prevent the ink from drying in the nozzles.

Abstract: A capping station is configured for storing printheads during printer inactivity to preserve the viscosity of the ink in the nozzles of the printheads. Each capping station has a receptacle, a planar member having a shaft that moves bidirectionally within an opening in a floor of the receptacle, a source of cleaning fluid, and a vacuum source. A controller is operatively connected to actuators to move the receptacle so a seal on an upper wall of the receptacle engages a printhead housing and to move the planar member within the receptacle. The controller also operates a pump to move cleaning fluid through the receptacle and to operate the vacuum source to pull ink from the nozzles of a printhead to the faceplate of the printhead. The planar member is moved proximate the faceplate so the ink forms a film that preserves the viscosity of the ink in the nozzles.

Abstract: A three-dimensional object printer comprises a conveyor having a surface configured to convey a three-dimensional object in a first direction; and a leveling assembly configured to level a surface of the three-dimensional object as the conveyer conveys the three-dimensional object in the first direction, the leveling assembly comprising (i) a roller having a cylindrical shape, the roller having an outer surface that moves upon the surface of the three-dimensional object to level the surface of the three-dimensional object; and (ii) a guide device arranged between the roller and the planar surface of the conveyer, the device being configured to mechanically interact with the roller to maintain a constant distance between the outer surface of the roller and the planar surface of the conveyer.

Abstract: Devices include electrically conductive elements contacting a vacuum belt, and a voltage source connected to the electrically conductive elements. The electrically conductive elements form an electrical circuit from the voltage source, through the belt, and back to the voltage source. The electrically conductive elements are positioned so that they are separated from the belt when the belt moves the sheets of media between the electrically conductive elements and the belt. A processor is capable of identifying leading edges of the sheets of media on the belt (when voltage of the electrical circuit changes from a relatively higher voltage to a relatively lower voltage) and identifying trailing edges of the sheets of media on the belt (when the voltage of the electrical circuit changes from the relatively lower voltage back to the relatively higher voltage).

Abstract: A three-dimensional object printer comprises a conveyor having a surface configured to convey a three-dimensional object in a first direction; a leveling assembly configured to level a surface of the three-dimensional object as the conveyer conveys the three-dimensional object in the first direction, the leveling assembly comprising (i) a member, (ii) a roller connected to the member having a cylindrical shape, the roller having an outer surface that moves upon the surface of the three-dimensional object to level a surface of the three-dimensional object, and (iii) an actuator arranged near the member, the actuator being configured to mechanically interact with the member to move the roller with respect to the planar surface of the conveyer; and a controller configured to, as the outer surface of the roller moves upon the surface of the three-dimensional object, operate the actuator to move the roller with respect the conveyer.

Abstract: A three-dimensional object printer comprises a platen, an ejector head having a plurality of ejectors configured to eject drops of material toward the platen, a sensor configured to measure heights of drops of material ejected onto the platen, and a controller operatively connected to the sensor and the ejector head. The controller is configured to operate the plurality of ejectors to eject drops of material toward the platen to form a first layer of material upon the platen; operate the sensor to measure a height profile of the first layer of material; and operate the plurality of ejectors to eject drops of material toward the platen to form a second layer of material upon the first layer of material with reference to the measured height profile.

Abstract: A three-dimensional object printer comprises a conveyor having a surface configured to convey a three-dimensional object in a first direction; and a leveling assembly configured to level a surface of the three-dimensional object as the conveyer conveys the three-dimensional object in the first direction, the leveling assembly comprising (i) a roller having a cylindrical shape, the roller having an outer surface that moves upon the surface of the three-dimensional object to level the surface of the three-dimensional object; and (ii) a guide device arranged between the roller and the planar surface of the conveyer, the device being configured to mechanically interact with the roller to maintain a constant distance between the outer surface of the roller and the planar surface of the conveyer.

Abstract: A three-dimensional object printer comprises a conveyor having a surface configured to convey a three-dimensional object in a first direction; a leveling assembly configured to level a surface of the three-dimensional object as the conveyer conveys the three-dimensional object in the first direction, the leveling assembly comprising (i) a member, (ii) a roller connected to the member having a cylindrical shape, the roller having an outer surface that moves upon the surface of the three-dimensional object to level a surface of the three-dimensional object, and (iii) an actuator arranged near the member, the actuator being configured to mechanically interact with the member to move the roller with respect to the planar surface of the conveyer; and a controller configured to, as the outer surface of the roller moves upon the surface of the three-dimensional object, operate the actuator to move the roller with respect the conveyer.

Abstract: A print head protection system is used in connection with an inkjet printer having a print head adapted for elevating, and a belt moving over a platen. A plurality of acoustic sensors is arrayed transversely to the process direction. The acoustic sensors measure a combined thickness of the belt, the platen, and the media sheet. An analyzer will detect if the media sheet is in contact with the media transport. An error signal is created when the thickness is below a predetermined value, indicating the media sheet is not in contact with the media transport. A mitigation control is operative to mitigate print head damage in response to the signal. Printing is halted in response to the signal to preclude damage to the print head. The sheet is discarded.

Abstract: A print head protection system is used in connection with an inkjet printer having a print head adapted for elevating, and a belt moving over a platen. A plurality of acoustic sensors is arrayed transversely to the process direction. The acoustic sensors measure a combined thickness of the belt, the platen, and the media sheet. An analyzer will detect if the media sheet is in contact with the media transport. An error signal is created when the thickness is below a predetermined value, indicating the media sheet is not in contact with the media transport. A mitigation control is operative to mitigate print head damage in response to the signal. Printing is halted in response to the signal to preclude damage to the print head. The sheet is discarded.

Abstract: A sheet-receiving surface comprises retractable bars movable between a first position and a second position. The first position is a first distance away from a mounting support. The second position is a second distance away from the mounting support. The first distance is greater than the second distance. Pivot arms, having a first end and a second end opposite the first end, are rotationally attached at the first end to the retractable bars and rotationally attached at the second end to the mounting support. Bias elements, operatively connected to the pivot arms, bias the retractable bars to the first position. A link is operatively connected to the retractable bars and an actuator. The sheet-receiving surface accumulates sheets of media into sets of sheets. Responsive to operation of the actuator, the link applies a force to move the retractable bars to the second position, forming an opening to allow the sets of sheets to drop, forming a stack of sets of sheets.

Abstract: A jetting-fault analysis system can include a print head with a plurality of nozzles for ejecting a print medium, a testing substrate that can include a carrier and at least one color-changing material that changes color and forms a color pattern upon exposure to at least one color-change inducer, an applicator for delivering a color-change inducer to the testing substrate, and a color-pattern imaging system for analyzing the color pattern.

Abstract: A print head protection system is used in connection with an inkjet printer having a print head adapted for elevating. A projector upstream of the print head projects a reference pattern onto the media sheet. An imaging camera captures a digital image of the projected pattern. An analyzer compares the digital image of the projected pattern with the reference pattern. If moiré fringes are detected, the moiré fringes are analyzed for media sheet curl. An error signal is created when the sheet curl exceeds a predetermined distance above the process path. A mitigation control raises the print head to preclude damage in response to the signal. Alternately, the sheet can be discarded.

Abstract: A shuttling nip set sheet inverter is for use with a digital printing system. A shuttle nip selectively rotates in a forward or reverse direction. The shuttle nip rollers are mounted for mutual revolving orbit about an orbital axis. The shuttle nip rollers are also mounted for mutual translation in the process direction. An inversion nip is disposed adjacent a main nip and downstream from the shuttle nip. A diverter gate has a first end adjacent the shuttle nip and a second end adjacent the inversion nip. In duplex operation, the media sheet lead edge will pass through the shuttle nip. The shuttle nip will revolve orbitally and translate downstream. The trail edge will become the lead edge, inverting the media sheet, which enters the main nip. The diverter gate moves from an inversion position to a storage position away from the process path.

Abstract: A jetting-fault analysis system can include a print head with a plurality of nozzles for ejecting a print medium, a testing substrate that can include a carrier and at least one color-changing material that changes color and forms a color pattern upon exposure to at least one color-change inducer, an applicator for deliver a color-change inducer to the testing substrate, and a color-pattern imaging system for analyzing the color pattern.

Abstract: An exemplary apparatus herein includes a registration item positioned at the end of a shelf. Further, tamper elements contact the sides of sheets of media on the shelf to align them and push them toward the registration item. In addition, a frame element is connected to each of the tamper elements and a biased member is connected to the frame element. A motor is connected to the biased member. Rotation of the motor moves the tamper elements in a closed curve path motion relative to the shelf and the registration item. With increasing speed of the rotation of the motor, the biased member expands, and this increases the distance of the closed curve path motion and increases the force applied by the tamper elements against the sheets of media being moved toward the registration item along the shelf.