An example method of performing a null cycle in a liquid electrographic printer is described. The method involves collecting, at a photo imaging plate cleaning station, imaging oil deposited on a photo imaging plate during a print cycle. During a null cycle, the photo imaging plate cleaning station is controlled to apply the collected imaging oil to the photo imaging plate.

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.

In a developer receiving portion 45, a receiving port 51 for receiving a liquid developer and a discharging port 57 for permitting discharge of the received liquid developer. A film forming electrode 44 is provided opposed to a developing roller 41 with a predetermined gap G and forms a film, on a surface of the developing roller 41, of the liquid developer supplied to the predetermined gap G through the discharging port 57. Further, the developer receiving portion 45 includes a partition plate 47 which partitions an inside space 45a, filled with the liquid developer supplied through the receiving port 51, into a first chamber 61 on the receiving port 51 side and a second chamber 62 on the discharging port 57 side. The partition plate 47 is provided with a plurality of communication ports 50 formed with respect to a liquid developer so as to communicate the first chamber 61 and the second chamber 62 with each other.

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.

Ink-based digital printing systems useful for ink printing include a photoreceptor layer configured to receive a layer of liquid immersion fluid. The liquid immersion fluid includes dampening fluid, dispersed gas particles, and charge directors that impart charge to the solid particles. The photoreceptor surface is charged to a uniform potential, and selectively discharged using an ROS according to image data to form an electrostatic latent image. The charged liquid immersion fluid adheres to portions of the photoreceptor surface according to the electrostatic latent image to form a fountain solution image. The fluid portion of the fountain solution image can be partially transferred to an imaging member and/or transfer member to form a dampening fluid image, either or both of which may be electrically biased. The dampening fluid image is inked on the transfer member, and the resulting ink image transferred to a print substrate.

During a print cycle of a print apparatus, a liquid print agent including a carrier fluid is applied to a photoconductive surface. A proportion of the carrier fluid in the liquid print agent on the photoconductive surface is reduced at a first location by removably collecting a portion of the carrier fluid from the liquid print agent applied to the photoconductive surface. During a non-print cycle of the print apparatus, the removably collected portion of the carrier fluid is added to the photoconductive surface at the first location.

A printing apparatus is described in which a guide member biases a printing substrate with a layer of printing fluid toward an electrode array with a plurality of electrodes. Processing circuitry determines a dryness of the layer of printing fluid based on an output of the electrode array when the plurality of electrodes is in electrical contact with the printing substrate.

Ink-based digital printing systems useful for ink printing include a photoreceptor layer configured to receive a layer of liquid immersion fluid. The liquid immersion fluid includes dampening fluid, dispersed gas particles, and charge directors that impart charge to the solid particles. The photoreceptor surface is charged to a uniform potential, and selectively discharged using an ROS according to image data to form an electrostatic latent image. The charged liquid immersion fluid adheres to portions of the photoreceptor surface according to the electrostatic latent image to form a fountain solution image. The fluid portion of the fountain solution image can be partially transferred to an imaging member and/or transfer member to form a dampening fluid image, either or both of which may be electrically biased. The dampening fluid image is inked on the transfer member, and the resulting ink image transferred to a print substrate.

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.

In one example of the disclosure, a set of scanned images is accessed. The scanned images are scans of distinct printouts of subject images produced utilizing an intermediate transfer member. A set of defect maps is created by comparing the scanned images to reference data for the subject images. The set of defect maps are combined into an integrated defect map. A dent defect on the ITM is identified utilizing the integrated defect map.