Abstract: A droplet ejection device includes a liquid ejection head, a supply flow path, a supply pump, and a supply flow path pressurizer. The supply flow path supplies the liquid to the head and for which a first depressurization threshold is specified in advance. The supply pump sucks the liquid, pressurizes the sucked liquid and supplies the sucked liquid to the head via the supply flow path, and keeps a pressure of liquid in the supply flow path near to a predetermined supply flow path target pressure. The supply flow path pressurizer pressurizes the pressure of liquid in the supply flow path if the pressure of liquid in the supply flow path falls to less than or equal to the first depressurization threshold.

Abstract: A droplet ejection apparatus includes droplet ejection units each including a supply port and an ejection port, a common supply flow path, a common discharge flow path, supply flow paths that connect the supply port to the common supply flow path, openable mechanisms provided at the supply flow paths, discharge flow paths that connect the ejection port to the common discharge flow path, one-way valves provided at the discharge flow paths, a pressure applying unit, and a controller. When performing a maintenance operation of a selected droplet ejection unit, the controller applies a pressure with the pressure applying unit so that the pressure in the plural discharge flow paths at the common discharge flow path side with respect to the respective one-way valves is higher than the other side, and opens only the openable mechanism corresponding to the selected droplet ejection unit.

Abstract: A droplet ejection apparatus includes a common flow path; droplet ejection units each respectively including a first distribution port; first flow paths that respectively connect each first distribution port to the common flow path; first open/close mechanisms provided respectively at the first flow paths; a first pressurizing unit that applies a positive pressure to the common flow path; a second open/close mechanisms provided at the common flow path at the first pressurizing unit side of connection portions that connect the common flow path and the respective first flow paths; and a controller. When the second open/close mechanism is closed, the controller opens only one or more first open/close mechanisms corresponding to one or more target droplet ejection units, applies positive pressure to a section of the common flow path at the first pressurizing unit side of the second open/close mechanism, and then opens the second open/close mechanism.