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; 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; 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 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 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 target senses whether and where it has been struck by a laser light. The target includes a screen for allowing laser light to pass through, a plurality of light sensors behind the screen, and an optical display associated with one or more of the light sensors. When the target is struck by a laser light, a sensor records the strike, and the target may be struck with laser light multiple times, whereby different sensors may record the different strikes. To determine whether and where the target has been struck, the user activates a display mode that causes the optical displays in the target to illuminate. The user can then reset the target so the user can begin again.

Abstract: A scissor lift apparatus includes a sliding carriage member and a pivoting linkage added to a conventional scissor lift in order to lower the force required to lift a tray holding heavy media during the initial portion of the lifting action where the scissor lift is fully compressed.

Abstract: A scissor lift apparatus includes a sliding carriage member and a pivoting linkage added to a conventional scissor lift in order to lower the force required to lift a tray holding heavy media during the initial portion of the lifting action where the scissor lift is fully compressed.

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.

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.

Abstract: A printer detects inoperative inkjets during printing of three dimensional objects. The printer includes an electrically conductive substrate onto which a printhead ejects building material in a test pattern. A plurality of electrically conductive members arranged in a pattern corresponding to the test pattern are moved a predetermined distance towards the substrate so ends of the members either contact the surface of the substrate or the building material on the substrate. An electrical current source coupled to the substrate produces a current in those members contacting the substrate. Thus, the inkjets corresponding to the members in which an electrical current is produced are identified as inoperative and the printing of an object can be suspended to take remedial action with regard to the printhead.