Ink-based digital printing systems useful for ink printing include a secondary roller having a rotatable reimageable surface layer configured to receive fountain solution. The fountain solution layer is patterned on the secondary roller and then partially transferred to an imaging blanket, where the fountain solution image is inked. The resulting ink image may be transferred to a print substrate. To achieve a very high-resolution (e.g., 1200-dpi, over 900-dpi) print with these secondary roller configurations, an equivalent very high-resolution fountain solution image needs to be transferred from the secondary roller onto the imaging blanket. To increase the resolution of the image on the secondary roller, examples include a textured surface layer added to the secondary roller for contact angle pinning the fountain solution on the roll. Approaches to introduce a micro-structure onto the surface layer of the secondary roller, and also superoleophobic surface coatings are described.

A formative surface having a conductive base covered with a dielectric and oleophobic/hydrophobic surface layer is created with defined pits to grow micro-puddles of a defined volume. The formative surface is brought into close proximity with a charge retentive surface carrying a charge image. Fountain solution vapor nucleates and grows preferentially on the base of the pits as micro-puddle droplets. The puddles are charged and extracted from the surface to provide a fog of charged droplets of narrow volume and charge distribution. The charged droplets are attracted and repelled respectively from the charged and discharged image regions of the charge retentive surface, thus developing the charged image into a fountain solution latent image. The developed latent image is then brought into contact with a transfer member blanket and split, thus creating on the blanket a fountain solution latent image ready for inking.

Ink-based digital printing systems useful for ink printing include a secondary roller having a rotatable reimageable surface layer configured to receive fountain solution. The fountain solution layer is patterned on the secondary roller and then partially transferred to an imaging blanket, where the fountain solution image is inked. The resulting ink image may be transferred to a print substrate. To achieve a very high-resolution (e.g., 1200-dpi, over 900-dpi) print with these secondary roller configurations, an equivalent very high-resolution fountain solution image needs to be transferred from the secondary roller onto the imaging blanket. To increase the resolution of the image on the secondary roller, examples include a textured surface layer added to the secondary roller for contact angle pinning the fountain solution on the roll. Approaches to introduce a micro-structure onto the surface layer of the secondary roller, and also superoleophobic surface coatings are described.

Based on evaporation of fountain solution from a rotating blanket cylinder to create an image that may be inked and printed, a digitally addressable heater array at or just below the blanket surface evaporates deposited fountain solution and forms a fountain solution latent image on the surface. The heater array has controllable heating elements (e.g., field effect transistors, thin film transistors) that provide a transient heat pattern on the surface to evaporate the fountain solution. Heat is generated by current flow in the heating elements, and power developed by the heating circuit is the product of source-drain voltage and current in the channel. Current may be supplied along data lines by an external voltage controlled by digital electronics to provide the desired heat at heating elements addressed by a specific gate line. The heater array may include a current return line that may be a 2-dimensional mesh.

Fountain solution latent images are provided on an inking blanket without using laser-induced evaporation systems. Approaches include a rotatable charge retentive surface configured to receive an unfused toned electrostatic pattern of toner particles adhered thereto via electrophotography. The toner includes small diameter polymeric or inorganic particles that may have no color pigment to appear transparent or translucent. Fountain solution is disposed on at least one of the toner, the charge retentive surface and a transfer substrate. The transfer substrate is adjacent the charge retentive surface and forms a nip therebetween, with the transfer substrate sandwiching the unfused toned electrostatic pattern of toner particles and fountain solution against the charge retentive surface at the nip. Fountain solution sandwiched between the surfaces splits as the surfaces separate downstream the nip, leaving a fountain solution latent image remaining on the transfer member surface based on the electrostatic charged pattern on the charge retentive surface.

A solid particle aerosol development device form fogs of solid (e.g., frozen) fountain solution particles that are charged, and brings the charged solid fountain solution particles into proximity of an electrostatic charged image pattern on a imaging member's charge retentive surface. The charged solid fountain solution particles bond to the charge retentive surface at the charged image pattern to develop that image into a fountain solution latent image. The solid particle aerosol development devices produce solid fountain solution particles to develop electrostatic latent images while mitigating issues of evaporation and vapor production, and thus may apply fine films of fountain solution which may otherwise evaporate. In examples, the fountain solution aerosol development devices may include an anilox member, a metering member in contact with the anilox member, a fountain solution reservoir, a particle charger and a particle delivery baffle.

Examples of the preferred embodiments use printed content (e.g., halftones, difference in grayscale or darkness) to determine thickness of fountain solution applied by a fountain solution applicator on an imaging member surface and/or determine image forming device real-time image forming modifications for subsequent printings. For example, in real-time during the printing of a print job, a sensor may measure halftones or grayscale differences between printed content and non-printed content of a current printing on print substrate. Based on this measurement of printed content output from the image forming device, the image forming device may adjust image forming (e.g., fountain solution deposition flow rate, imaging member rotation speed) to reach or maintain a preferred fountain solution thickness on the imaging member surface for subsequent (e.g., next) printings of the print job.

A multilayer imaging blanket for a variable data lithography system, including a multilayer base including a sulfur-containing layer; and a cured topcoat layer including a polyurethane in contact with the sulfur-containing layer of the multilayer base.

A roller arrangement for printing apparatus comprises a first roller. The first roller comprises a plurality of cells. Each of the plurality of cells receives an amount of a coating material. The roller arrangement further comprises an extractor to remove at least a portion of the coating material from a selected set of the plurality of the cells.

There is disclosed a selective wetting apparatus (2) comprising a roller (20) rotatable about a roller axis (24) and comprising a wettable roller surface (22); an applicator unit (10) having a lip (12) which extends parallel to the roller axis (24) and is radially spaced apart from the roller surface (22) by a gap (30), wherein the applicator unit (10) is to convey liquid agent (14) towards the roller (20) so that the liquid agent (14) forms a liquid bridge (32) over the gap (30) to wet a wettable axial portion of the roller surface (22); and a flow guide (50) to direct a gas flow (56) into a regulated axial portion of the gap (30) to locally prevent formation of a liquid bridge (32), and thereby prevent wetting of a corresponding axial portion of the roller surface (22).