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.

An optical light reflectance measurement system above an imaging member surface measures fountain solution surface light reflectance interference on reflective substrate portions of the imaging member surface in real-time during a printing operation. The measured light reflectance interference corresponds to a thickness of the fountain solution layer and may be used in a feedback loop to actively control fountain solution layer thickness by adjusting the volumetric feed rate of fountain solution added onto the imaging member surface during a printing operation to reach a desired uniform thickness for the printing. This fountain solution monitoring system may be fully automated.

A coefficient of friction (COF) sensor on a carrier roll surface wetted with fountain solution transferred from an imaging member measures COF of the wetted carrier roll surface in real-time, even between or during printing operations. The transferred fountain solution may be concentrated and/or chilled to solidify before the measurement. The measured COF is used in a feedback loop to actively control the fountain solution layer thickness by adjusting the volumetric feed rate of fountain solution added onto the imaging member surface during an imaging or other printing operation to reach a desired uniform thickness for the printing. This fountain solution monitoring system may be fully automated.

An image based correction system compensates for the image quality artifacts induced by thermal ghosting on evolving imaging member surfaces. With thermal ghosting directly tied to previous image content, a feed forward system determines thermal ghosting artifacts based on images previously rendered and generates an open loop gray-level correction to a current image that mitigates undesirable ghosting. For example, the correction system compensates for the thermal ghosting by making the current image “lighter” in areas that will be imaged onto warmer blanket regions, thereby cancelling out TRC differences between different temperature regions. A temperature sensor is used to measure the temperature of the imaging blanket due to the stresses induced by the image. This data is used to learn the parameters of the temperature model periodically during operation, and used in subsequent corrections to mitigate thermal ghosting in spite of changes in blanket properties over use and time.

A method for direct transfer printing is disclosed. The method for direct transfer printing includes applying a fountain solution to an imaging blanket in a negative imagewise manner using an inkjet printhead, contacting the imaging blanket with a printing substrate, transferring the fountain solution from the imaging blanket to the printing substrate, contacting the printing substrate with an inking station, and depositing an ink film from the inking station to the printing substrate in one or more locations on the printing substrate where there is no fountain solution. A module for a direct transfer marking process and a direct transfer printing system are also disclosed.

A method for direct transfer printing is disclosed. The method for direct transfer printing includes applying a fountain solution to an imaging blanket in a negative imagewise manner using an inkjet printhead, contacting the imaging blanket with a printing substrate, transferring the fountain solution from the imaging blanket to the printing substrate, contacting the printing substrate with an inking station, and depositing an ink film from the inking station to the printing substrate in one or more locations on the printing substrate where there is no fountain solution. A module for a direct transfer marking process and a direct transfer printing system are also disclosed.

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

A coefficient of friction (COF) sensor on a carrier roll surface wetted with fountain solution transferred from an imaging member measures COF of the wetted carrier roll surface in real-time, even between or during printing operations. The transferred fountain solution may be concentrated and/or chilled to solidify before the measurement. The measured COF is used in a feedback loop to actively control the fountain solution layer thickness by adjusting the volumetric feed rate of fountain solution added onto the imaging member surface during an imaging or other printing operation to reach a desired uniform thickness for the printing. This fountain solution monitoring system may be fully automated.

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.

According to aspects of the embodiments, there is provided a method of measuring the amount of fountain solution employed in a digital offset lithography printing system. Fountain solution thickness is measured using a diffractive optical element (DOE) configured with grating surfaces varying in a periodic fashion to hold an amount of fountain solution. When radiated with a light source the combination of the grating surface and the fountain solution therein reduces the scattering of the surface structure (“contrast”) that gives rise to a diffraction pattern. The diffractive optical element can be placed on the printing blanket of the lithography printing system or on a separate substrate.