Abstract: In one aspect an apparatus for use in an electrographic printer is described. The apparatus includes a housing defining a cavity, a developer roller, a developer electrode for developing printing substance onto the developer roller, the electrode being arranged within the cavity, and a heater for heating printing substance to be developed onto the developer roller, the heater being arranged in the cavity.

Abstract: 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. The assembly may also include a print agent regulator roller to regulate a film thickness of print agent on the print agent transfer roller. The assembly may also include a mechanism to generate an oscillating force to be applied to print agent on the print agent transfer roller. A method and a print apparatus are also disclosed.

Abstract: In one example of the disclosure, a developer system includes a housing and a developer roller. A first electrode and a second electrode are disposed in the housing, the first and second electrodes to create an electrical charge to cause transfer of printing fluid to a developer roller surface. The developer roller is rotatably connected to the housing. The developer includes a surface, a bearing to support and enable rotation of an axle attached to the developer roller, and a plurality of stop pins. The plurality of stop pins are connected to the housing. The stop pins are to support the bearings and to establish target distances between the developer roller surface and the first electrode and second electrodes.

Abstract: A method of printing images in a liquid electrophotographic printer is provided. In an example, the method includes measuring at least one current associated with an image development unit of the liquid electrophotographic printer. A first time at which a peak occurs in the measured current is determined; the first time indicates that a printing substance is transferred from a point on a developer roller of the image development unit to a photo imaging member of the liquid electrophotographic printer at a first location within the image development unit. A second time at which said point on the developer roller is expected to contact the cleaner roller within the image development unit is calculated and, at the second time, a voltage applied to the cleaner roller is controlled to reduce the potential difference between the cleaner roller and the developer roller.

Abstract: 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. The assembly may also include a print agent regulator roller to regulate a film thickness of print agent on the print agent transfer roller. The assembly may also include a mechanism to generate an oscillating force to be applied to print agent on the print agent transfer roller. A method and a print apparatus are also disclosed.

Abstract: In one example of the disclosure, a developer system includes a housing and a developer roller. A first electrode and a second electrode are disposed in the housing, the first and second electrodes to create an electrical charge to cause transfer of printing fluid to a developer roller surface. The developer roller is rotatably connected to the housing. The developer includes a surface, a bearing to support and enable rotation of an axle attached to the developer roller, and a plurality of stop pins. The plurality of stop pins are connected to the housing. The stop pins are to support the bearings and to establish target distances between the developer roller surface and the first electrode and second electrodes.

Abstract: In one example, a flow structure for an ink supply in a liquid electrophotographic developer unit includes an elongated basin having a volume that shrinks progressively from an upstream part of the basin to a downstream part of the basin such that a rate of shrinkage increases towards the downstream part.

Abstract: In one aspect an apparatus for use in an electrographic printer is described. The apparatus includes a housing defining a cavity, a developer roller, a developer electrode for developing printing substance onto the developer roller, the electrode being arranged within the cavity, and a heater for heating printing substance to be developed onto the developer roller, the heater being arranged in the cavity.

Abstract: A method of printing images in a liquid electrophotographic printer is provided. In an example, the method comprises measuring at least one current associated with an image development unit of the liquid electrophotographic printer. A first time at which a peak occurs in the measured current is determined; the first time indicates that a printing substance is transferred from a point on a developer roller of the image development unit to a photo imaging member of the liquid electrophotographic printer at a first location within the image development unit. A second time at which said point on the developer roller is expected to contact the cleaner roller within the image development unit is calculated and, at the second time, a voltage applied to the cleaner roller is controlled to reduce the potential difference between the cleaner roller and the developer roller.

Abstract: In one example, a flow structure for an ink supply in a liquid electrophotographic developer unit includes an elongated basin having a volume that shrinks progressively from an upstream part of the basin to a downstream part of the basin such that a rate of shrinkage increases towards the downstream part.

Abstract: In one aspect an apparatus (200) for use in an electrographic printer (100) is described. The apparatus includes a housing (210) defining a cavity (220), a developer roller (250), a developer electrode (240) for developing printing substance onto the developer roller, the electrode being arranged within the cavity, and a heater (260) for heating printing substance to be developed onto the developer roller, the heater being arranged in the cavity.

Abstract: In one aspect an apparatus for use in an electrographic printer is described. The apparatus includes a housing having a base, a first wall, and a second wall, wherein the housing defines a cavity. The apparatus also includes a developer roller and an ink developer electrode for developing ink to the developer roller. The apparatus also includes an ink outlet, and a gutter for directing ink in the cavity towards the ink outlet, the gutter being disposed between the first wall and second wall, and between the developer roller and base. The gutter has a floor, a first side, and a second side, each extending along a length of the gutter. The floor slopes towards the ink outlet to direct ink towards the ink outlet, and the floor and sides of the gutter form a curve transverse to the length of the gutter to direct ink towards the floor.

Abstract: An example method of controlling the concentration of a printing substance is provided. A layer of printing substance is received on a printing substance receiving member, and a parameter indicative of a current concentration of non-volatile material in the printing substance is measured. The current concentration is compared to a predetermined target concentration. Based on the comparison, a concentration adjustment is determined. The adjustment comprises at least one of (i) an adjustment to a pressure applied to the printing substance receiving member by a pressurizing member, and (ii) an adjustment to a voltage applied to the pressurizing member. The concentration of the printing substance is controlled based on the determination.

Abstract: A print agent supply unit includes: an inlet chamber to distribute print agent within the print agent supply unit; a valve to selectively permit print agent into the inlet chamber, the valve including: a print agent inlet opening; and a valve member to selectively close the print agent inlet opening, the valve member being tapered towards an upstream end of the valve member.

Abstract: In one aspect an apparatus for use in an electrographic printer includes a tray defining a cavity, the tray having an internal surface, and an ink developer electrode disposed in the cavity for developing an ink. There is a first layer disposed on the internal surface, the first layer including a dielectric material, and a second layer disposed on the first layer, the second layer adhering to the first layer and being resistant to the adhesion of ink. In another aspect manufacturing such apparatus includes applying respective polymer precursor compositions to form the two layers and crosslinking the second polymer composition.

Abstract: In one aspect an apparatus for use in an electrographic printer is described. The apparatus includes a housing having a base, a first wall, and a second wall, wherein the housing defines a cavity. The apparatus also includes a developer roller and an ink developer electrode for developing ink to the developer roller. The apparatus also includes an ink outlet, and a gutter for directing ink in the cavity towards the ink outlet, the gutter being disposed between the first wall and second wall, and between the developer roller and base. The gutter has a floor, a first side, and a second side, each extending along a length of the gutter. The floor slopes towards the ink outlet to direct ink towards the ink outlet, and the floor and sides of the gutter form a curve transverse to the length of the gutter to direct ink towards the floor.

Abstract: In one aspect an apparatus (200) for use in an electrographic printer (100) is described. The apparatus includes a housing (210) defining a cavity (220), a developer roller (250), a developer electrode (240) for developing printing substance onto the developer roller, the electrode being arranged within the cavity, and a heater (260) for heating printing substance to be developed onto the developer roller, the heater being arranged in the cavity.

Abstract: A print agent supply unit comprising: an inlet chamber to distribute print agent within the print agent supply unit; a valve to selectively permit print agent into the inlet chamber, the valve comprising: a print agent inlet opening; and a valve member to selectively close the print agent inlet opening, the valve member being tapered towards an upstream end of the valve member.

Abstract: In one aspect an apparatus (200) for use in an electrographic printer includes a tray (260) defining a cavity (262), the tray having an internal surface, and an ink developer electrode (250) disposed in the cavity for developing an ink. There is a first layer (264) disposed on the internal surface, the first layer comprising a dielectric material, and a second layer (266) disposed on the first layer, the second layer adhering to the first layer and being resistant to the adhesion of ink. In another aspect manufacturing such apparatus comprises applying respective polymer precursor compositions to form the two layers and crosslinking the second polymer composition.

Abstract: In an example, rollers are disclosed, wherein one of the rollers has a resilient outer layer, and one of the rollers comprises a coned portion.