Measures for controlling an engagement force between a photo imaging plate (110) and a developer roller (200) in a printing device (100) are described. A motor (310) is operated to generate rotational motion. The rotational motion is translated into linear motion. The linear motion causes an adjustment to the engagement force between the developer roller and the photo imaging plate. A characteristic of the motor is monitored. The motor is controlled on the basis of the monitored characteristic in order to maintain a desired engagement force between the developer roller and the photo imaging plate.

Example implementations relate to a printing an image on a substrate and printing an ultraviolet-sensitive finishing mark on the substrate using ultraviolet-sensitive ink. The ultraviolet-sensitive finishing mark can be visible under ultraviolet light.

Example implementations relate to a printing an image on a substrate and printing an ultraviolet-sensitive finishing mark on the substrate using ultraviolet-sensitive ink. The ultraviolet-sensitive finishing mark can be visible under ultraviolet light.

In some examples, a printing liquid developer includes a developer roller that has a hollow tubular base body formed of a material including conductive carbon fiber, a conductive, compliant layer around an outer surface of the hollow tubular base body, and an electrically conductive support separate from the hollow tubular base body and electrically contacted to a surface of the hollow tubular base body.

Example implementations provide a method of controlling an ink developer used in electro-photography; the method comprising, following cessation of printing, varying a plurality of voltages associated with movement of ink within the ink developer at temporally disparate times.

A developing roller which is rotatable while carrying a liquid developer containing toner and a carrier liquid and which contains an electroconductive agent, a squeeze roller provided in contact with the developing roller through at least the carrier liquid, a voltage source capable of generating a potential difference between the developing roller and a squeeze roller, a current detecting sensor for detecting a current passed between the developing roller and the squeeze roller, a controller capable of controlling the voltage source, and a display device capable of outputting information on a lifetime of the developing roller are provided, and the controller outputs the information on the lifetime from the display device on the basis of a detection result by the current detecting sensor (steps S5 to S8) when a predetermined potential difference is generated between the developing roller and the squeeze roller by the voltage source (steps S2, S4).

In one example of the disclosure, it is determined that an amount of print agent remaining in a print agent container of a print apparatus is below a threshold level. An amount of print solution is transferred from a print solution reservoir of the print apparatus, or an amount of print solution solvent is transferred from a solvent reservoir of the print apparatus, into the print agent container. At least some of the remaining print agent is caused to dissolve into the amount of print solution or print solution solvent to forma rinse solution. The rinse solution is transferred from the print agent reservoir to the print solution reservoir.

Example implementations provide a method of controlling an ink developer used in electro-photography; the method comprising, following cessation of printing, varying a plurality of voltages associated with movement of ink within the ink developer at temporally disparate times.

Example implementations relate to a printing an image on a substrate and printing an ultraviolet-sensitive finishing mark on the substrate using ultraviolet-sensitive ink. The ultraviolet-sensitive finishing mark can be visible under ultraviolet light.

A developing apparatus includes a developer carrier that carries a developer, and a developer casing that contains the developer to be supplied to the developer carrier. An opening/closing part is capable of controlling a moving amount of the developer between a first region on one side in an axial direction of the developer carrier and a second region on the other side in the axial direction of the developer carrier by opening or closing the first region and the second region. A hardware processor controls an open/closed state of the opening/closing part in accordance with the state of the developer in the first region and the second region.