Abstract: A three-dimensional printing system includes a vertical support beam, a resin vessel assembly coupled to the vertical support beam and including a resin vessel, and a support tray positioning system. The support tray positioning system includes a support tray elevator, a lead screw nut, a motorized lead screw, an intermediate nut, and a linear bearing. The motorized lead screw engages the lead screw nut to raise and lower the support tray elevator. The linear bearing constrains motion of the support tray elevator to vertical motion. The support tray elevator, the intermediate nut, and the lead screw nut interlock to constrain rotational motion of the lead screw nut with respect to the support tray elevator while allowing for two dimensional lateral motion of the lead screw nut with respect to the support tray elevator to accommodate mechanical tolerances of the lead screw with respect to the linear bearing.

Abstract: In an example, a print agent application assembly includes a print agent transfer roller to receive print agent and transfer a portion of the print agent to a photoconductive surface and a print agent regulator roller to regulate a film thickness of print agent on the print agent transfer roller. The print agent regulator roller may include a nip forming region and a first mounting region. The print agent application assembly may further include a first resilient component which spans a diametrical width of the print agent regulator roller and acts on the print agent regulator roller outside the nip forming region to impart a lateral force to the first mounting region, the lateral force urging the print agent regulator roller towards the print agent transfer roller.

Abstract: A print agent application assembly is disclosed. The print agent application assembly may include a first roller to remove print agent from a surface of a print agent transfer roller. The print agent application assembly may include a second roller having an absorbent element to engage the first roller as the second roller rotates relative to the first roller, the absorbent element to absorb print agent from the first roller. The print agent application assembly may include a wiper assembly. The wiper assembly may include a wiper element to scrape print agent from the surface of the first roller as the first roller rotates, and an engagement element to engage with and compress a portion of the absorbent element of the second roller as the second roller rotates relative to the wiper assembly. A method and a roller cleaning assembly are also disclosed.

Abstract: In one example, a developer roller for liquid electrophotographic printing includes a cylindrical metal inner core, a rigid conductive plastic outer core surrounding the inner core, and a compliant exterior surrounding the outer core.

Abstract: A three-dimensional printing system includes a support plate and a resin vessel. The support plate defines a central opening and an upper surface. The resin vessel is disposed upon the upper surface of the support plate and includes a substructure and a transparent sheet. The substructure includes a vertical wall and a tension ring that extends inwardly and downwardly from the vertical wall. The tension ring impinges downwardly upon an upper surface of the transparent sheet and tensions the transparent sheet.

Abstract: A technique includes rotating a squeegee roller to regulate a film thickness of ink on a developer roller; and using the developer roller to transfer a portion of the ink from the developer roller to a photoconductive member. The technique includes creating, by an electrode, a potential bias with the developer roller to transfer the ink to the developer roller; and inhibiting flow streaks on the developer roller, where inhibiting the flow streaks includes restricting a flow of ink between the squeegee roller and the electrode.

Abstract: In one example, a seal for a developer roller in a liquid electrophotographic printer includes an arcuate body curved along a body arc. The body has an inboard face that defines an annular sealing surface along the body arc to contact a face on one end of the developer roller and a guide surface across the body arc at a first end of the annular sealing surface. The guide surface is oriented along a chord of the body arc and intersects the body arc at an obtuse interior angle, to guide any ink encountering the guide surface outward toward the circular outer surface of the developer roller.

Abstract: A binary printing fluid developer assembly may include a developer roller to receive a printing fluid and transfer a portion of the printing fluid to a photoconductive member; a number of electrodes to create an electrical potential bias between the number of electrodes and the developer roller; a cleaner roller to remove an amount of printing fluid from the developer roller; and a sponge roller to clean the cleaner roller wherein a gap is maintained between the sponge roller and the number of electrodes.

Abstract: A printing fluid developer that includes a developer roller; a cleaner roller forming a nip with the developer roller and held by a number of bearings at each end that are free to move within a slot towards and away from the developer roller; and at least one spring biased to force the bearings towards one side of the slot.

Abstract: In one example, a sealing system for a developer roller in a liquid electrophotographic printer includes a pair of arcuate seals each with an annular sealing surface to seal one end of the developer roller; a pair of washers each having a low friction surface to contact one of the sealing surfaces; and a pair of retainers each to hold one of the washers flat against the end of the roller.

Abstract: A three-dimensional printer includes a light engine, a support plate, and a resin vessel. The light engine is configured to selectively harden photocurable resin at a build plane in the resin vessel. The support plate is formed from cast metal and is in a fixed vertical relation to the light engine. The support plate includes an upper side with an upstanding ridge. The upstanding ridge has an upper datum surface that has been machined to a controlled height. The support plate also includes a separately formed ring disposed upon the upper datum surface. The separately formed ring defines a crest of the upstanding ridge. The resin vessel includes a transparent sheet that defines a lower bound for resin contained in the resin vessel. The transparent sheet impinges upon the crest to define a vertical location of the build plane in relation to the light engine.

Abstract: A method of assembling a three-dimensional printing system includes providing a plurality of components, providing a plurality of spacer rings, and measurement, analysis and assembly steps. The components include a light engine, an adaptive support apparatus, a plurality of elongate struts, and a support plate. The measurement, analysis and assembly steps include (1) measuring a scale factor for the light engine, (2) determining a selection of one or more of the spacer rings based upon the measured scale factor, and (3) assembling the components with the determined selection of one or more spacer rings.

Abstract: A three dimensional printer includes a projector, an adaptive support apparatus, a resin support apparatus, and a plurality of vertical struts. The projector includes a projection lens module which includes an optical housing that contains a series of lenses for projecting an image from the projector onto a build plane. The projection lens module includes a laterally extending flange having an upwardly facing flange surface. The adaptive support apparatus includes a downward facing surface in facing relation with the upward facing flange surface. The resin support apparatus is configured to contain resin and includes a transparent sheet and a downward facing surface. The transparent sheet defines a lower bound for the resin proximate to a build plane. The plurality of vertical struts couple an upward-facing surface of the adaptive support apparatus to the downward-facing surface of the resin support apparatus.

Abstract: In an example, a print agent application assembly includes a print agent transfer roller to receive print agent and transfer a portion of the print agent to a photoconductive surface and a print agent regulator roller to regulate a film thickness of print agent on the print agent transfer roller. The print agent regulator roller may include a nip forming region and a first mounting region. The print agent application assembly may further include a first resilient component which spans a diametrical width of the print agent regulator roller and acts on the print agent regulator roller outside the nip forming region to impart a lateral force to the first mounting region, the lateral force urging the print agent regulator roller towards the print agent transfer roller.

Abstract: An example developer unit includes a developer roller. The developer unit also includes a set of electrodes proximate to the developer roller. The set of electrodes form a cavity. The developer unit includes an inlet to the cavity. The inlet is to receive printing fluid. The developer unit includes an insert in the inlet. The insert is to distribute the printing fluid evenly in the cavity.

Abstract: A transmission for a developer unit that includes a developer roller to apply LEP ink to a photoconductor, a cleaner roller to clean the developer roller, and a squeegee roller to squeegee ink on the developer roller. In one example, the transmission includes a mechanical drive train to, with the cleaner roller, simultaneously drive the developer roller at a first surface speed and the squeegee roller at a second surface speed slower than the first surface speed.

Abstract: A print agent application assembly is disclosed. The print agent application assembly may include a first roller to remove print agent from a surface of a print agent transfer roller. The print agent application assembly may include a second roller having an absorbent element to engage the first roller as the second roller rotates relative to the first roller, the absorbent element to absorb print agent from the first roller. The print agent application assembly may include a wiper assembly. The wiper assembly may include a wiper element to scrape print agent from the surface of the first roller as the first roller rotates, and an engagement element to engage with and compress a portion of the absorbent element of the second roller as the second roller rotates relative to the wiper assembly. A method and a roller cleaning assembly are also disclosed.

Abstract: In one example, a seal for a developer roller in a liquid electrophotographic printer includes an arcuate body curved along a body arc. The body has an inboard face that defines an annular sealing surface along the body arc to contact a face on one end of the developer roller and a guide surface across the body arc at a first end of the annular sealing surface. The guide surface is oriented along a chord of the body arc and intersects the body arc at an obtuse interior angle, to guide any ink encountering the guide surface outward toward the circular outer surface of the developer roller.

Abstract: An example developer unit includes a developer roller. The developer unit also includes a set of electrodes proximate to the developer roller. The set of electrodes form a cavity. The developer unit includes an inlet to the cavity. The inlet is to receive printing fluid. The developer unit includes an insert in the inlet. The insert is to distribute the printing fluid evenly in the cavity.

Abstract: A system for manufacturing a three-dimensional article includes a resin vessel, a vertical movement mechanism, and a light engine. The resin vessel includes a lower opening closed by a transparent sheet. The vertical movement mechanism is for positioning a support tray which supports the three-dimensional article. The light engine is disposed below the transparent sheet and is configured to selectively harden layers of resin over a build plane above the transparent sheet. The light engine includes a light bar coupled to a lateral movement mechanism. The light bar includes an array of light emitting devices and a device for impinging upon the transparent sheet. The impingement maintains a proper operating distance H between the transparent sheet and the build plane.