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.

A printing system to hold printing material comprises a sealing interface to seal a container with respect to a printing chamber volume of the printing system, the container to hold the printing material. The printing system comprises a lifting system to move the container between a first position in which the container is to be lifted and a second position at which the container is lifted and contacts the seal so as to seal the container. The lifting system is to non-hyperstatically constrain the container.

The invention relates to a sealing element for an ink chamber of a rotary printing press, wherein the sealing element has a sealing surface that rests against a roller body during operation of the rotary printing press. In order to reduce wear on the sealing element, the sealing surface has at least one flow outlet opening, at which an overpressure of a fluid may be built up during operation of the rotary printing press, in such a way that the fluid between the sealing surface and roller body forms a sealing flow film.

An ultra-high resolution capacitive sensor affixed above an imaging member surface measures the thickness of fountain solution on the imaging member surface in real-time during a printing operation. The sensor is considered ultra-high resolution with a resolution high enough to detect nanometer scale thicknesses. The capacitive sensor would initially be zeroed to the imaging member surface. As fluid is added, the capacitive sensor detects the increase and can measure and communicate with the image forming device to adjust fountain solution flow rate to the imaging member surface and correct for any anomalies in thickness. This fountain solution monitoring system may be fully automated. The capacitive sensor may have a resolution (e.g., as low as about 1 nm resolution) of about 0.001% of the distance/gap that the capacitive sensor is mounted away from the imaging member 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 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.

In one example in accordance with the present disclosure, a printing fluid container for a printing system is described. The printing fluid container includes a container body for holding printing fluid, a collar connected to the container body, and a cap removably engaging the collar. The collar has a plurality of collar teeth extending peripherally around the collar. The cap has a plurality of cap teeth extending peripherally around the cap. The cap teeth are configured for interfitment with the collar teeth such that rotation of the cap about the longitudinal axis in a first rotational direction effects cam-actuated removal of the cap from the collar.

In one example in accordance with the present disclosure, a printing fluid container for a printing system is described. The printing fluid container includes a container body for holding printing fluid, a collar connected to the container body, and a cap removably engaging the collar. The collar has a plurality of collar teeth extending peripherally around the collar. The cap has a plurality of cap teeth extending peripherally around the cap. The cap teeth are configured for interfitment with the collar teeth such that rotation of the cap about the longitudinal axis in a first rotational direction effects cam-actuated removal of the cap from the collar.

Provided is an electromagnetic wave generator including: an electromagnetic wave generation section that generates an electromagnetic wave; a high-frequency voltage generation section that generates a voltage applied to the electromagnetic wave generation section; and a transmission line that electrically couples the electromagnetic wave generation section and the high-frequency voltage generation section to each other, in which the electromagnetic wave generation section includes a first electrode, a second electrode, a first conductor that electrically couples the first electrode and the transmission line to each other, and a second conductor that electrically couples the second electrode and the transmission line to each other, one of the first electrode or the second electrode is a reference potential electrode to which a reference potential is applied and the other is a high-frequency electrode to which a high-frequency voltage is applied, a minimum separation distance between the first electrode and the second electrode is 1/10 or less of a wavelength of an output electromagnetic wave, a minimum separation distance between the first conductor and the second conductor is 1/10 or less of a wavelength of an output electromagnetic wave, and the first conductor further includes a coil, and the coil is closer to the first electrode than the transmission line.

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.