An example printing fluid pen comprises a plurality of fluid ports, including an inlet port to direct fluid from a fluid reservoir to a fluid ejection device, and a recirculation port to direct fluid from the fluid ejection device out of the inkjet pen. The example pen also includes a plurality of parallel fluid pressure regulators fluidly coupled with the inlet port, each of the plurality of parallel fluid pressure regulators to receive fluid from the inlet fluid port.

An example printing fluid pen comprises a plurality of fluid ports, including an inlet port to direct fluid from a fluid reservoir to a fluid ejection device, and a recirculation port to direct fluid from the fluid ejection device out of the inkjet pen. The example pen also includes a plurality of parallel fluid pressure regulators fluidly coupled with the inlet port, each of the plurality of parallel fluid pressure regulators to receive fluid from the inlet fluid port.

A method of filling a print head includes drawing a vapor into an empty print head to displace any air in the print head and filling the print head with ink. A method of filling a print head includes connecting a print head to a vacuum pump using a first valve, to a liquid supply using a second valve, and to an ink supply using a third valve, opening the first and second valves, applying vacuum to the print head and liquid supply using the vacuum pump, causing the liquid to generate a vapor that moves into the print head, closing the first valve and the second valve, and opening the third valve to move ink into the print head.

A method of filling a print head includes drawing a vapor into an empty print head to displace any air in the print head and filling the print head with ink. A method of filling a print head includes connecting a print head to a vacuum pump using a first valve, to a liquid supply using a second valve, and to an ink supply using a third valve, opening the first and second valves, applying vacuum to the print head and liquid supply using the vacuum pump, causing the liquid to generate a vapor that moves into the print head, closing the first valve and the second valve, and opening the third valve to move ink into the print head.

An apparatus (and a corresponding operation method) for automated maskless painting of an external paint on a complex surface using a coloring agent, wherein the complex surface is part of an aircraft. The apparatus comprises a multi-axis robot comprising at least one applicator for the coloring agent, wherein the at least one applicator is configured to apply the coloring agent to the complex surface using a coloring agent ejection technology.

Printhead priming can, in various examples, employ a conduit and a divider such that a predetermined portion of a pressurized gas in the conduit is provided to an environment surrounding the divider and a remaining portion of the pressurized gas in the conduit is provided to a printhead at a pressure sufficient to prime an ink supply.

A liquid ejection head includes a pressure chamber, an upstream channel, a downstream channel, a pump, an inflow channel, and a bypass channel. The upstream channel communicates with the pressure chamber to supply the liquid to the pressure chamber. The downstream channel communicates with the pressure chamber. The pump communicates with the upstream channel and the downstream channel to cause the liquid in the downstream channel to flow into the upstream channel. The inflow channel communicates with the upstream channel to cause the liquid to be supplied to the pressure chamber to flow into the upstream channel. The upstream channel and the downstream channel communicate with each other through the bypass channel without the pressure chamber being between the upstream channel and the downstream channel. Part of the liquid flowing from the upstream channel into the bypass channel flows into the pressure chamber through the downstream channel.

A liquid ejection head includes a pressure chamber, an upstream channel, a downstream channel, a pump, an inflow channel, and a bypass channel. The upstream channel communicates with the pressure chamber to supply the liquid to the pressure chamber. The downstream channel communicates with the pressure chamber. The pump communicates with the upstream channel and the downstream channel to cause the liquid in the downstream channel to flow into the upstream channel. The inflow channel communicates with the upstream channel to cause the liquid to be supplied to the pressure chamber to flow into the upstream channel. The upstream channel and the downstream channel communicate with each other through the bypass channel without the pressure chamber being between the upstream channel and the downstream channel. Part of the liquid flowing from the upstream channel into the bypass channel flows into the pressure chamber through the downstream channel.

A printer includes an ink ejecting section that ejects ink from a nozzle, an ink circulation path including an ink flow path through which the ink can be supplied to an ink ejecting section and an ink return path through which the ink supplied to the ink ejecting section is returned, a warming device including a temperature control module provided in the ink circulation path, where the warming device can heat the ink in the temperature control module, and a feed pump that can flow the ink in the ink circulation path, wherein the flow rate of the ink, in the ink circulation path, heated by the warming device is adjusted.

A printer includes an ink ejecting section that ejects ink from a nozzle, an ink circulation path including an ink flow path through which the ink can be supplied to an ink ejecting section and an ink return path through which the ink supplied to the ink ejecting section is returned, a warming device including a temperature control module provided in the ink circulation path, where the warming device can heat the ink in the temperature control module, and a feed pump that can flow the ink in the ink circulation path, wherein the flow rate of the ink, in the ink circulation path, heated by the warming device is adjusted.