A head module includes a pressure chamber, a piezoelectric member, a supply manifold, a return manifold, and a damper portion. The pressure chamber is configured to hold liquid therein and in fluid communication with a nozzle orifice. The piezoelectric member is configured to apply pressure to liquid held in the pressure chamber. The supply manifold is in fluid communication with the pressure chamber and configured to allow liquid to flow into the pressure chamber therefrom. The return manifold is in fluid communication with the pressure chamber and configured to allow liquid not ejected from the nozzle orifice to flow thereinto. The damper portion is positioned between the supply manifold and the return manifold when viewed in plan from a nozzle surface of the head module. The nozzle surface has the nozzle orifice defined therein. The damper portion includes a particular plate having a particular recessed portion.

A liquid discharge head is provided, the liquid discharge head comprising a plurality of individual channels, a first manifold connected to the plurality of individual channels, a second manifold connected to the plurality of individual channels, and a bypass channel connecting the first manifold and the second manifold and being distinct from the individual channels. A flow channel resistance Rct brought about by the plurality of individual channels, a flow channel resistance Rbp of the bypass channel, a bending loss ΔP provided when the liquid flows from the first manifold via the bypass channel to the second manifold, and a flow rate Q of the liquid flowing through the bypass channel fulfill a relationship of:
0.5<[Rct/(Rbp+(ΔP/Q))]<2.0.

A liquid discharge head is provided, the liquid discharge head comprising a plurality of individual channels, a first manifold connected to the plurality of individual channels, a second manifold connected to the plurality of individual channels, and a bypass channel connecting the first manifold and the second manifold and being distinct from the individual channels. A flow channel resistance Rct brought about by the plurality of individual channels, a flow channel resistance Rbp of the bypass channel, a bending loss ΔP provided when the liquid flows from the first manifold via the bypass channel to the second manifold, and a flow rate Q of the liquid flowing through the bypass channel fulfill a relationship of:
0.5<[Rct/(Rbp+(ΔP/Q))]<2.0.

An example recirculation fluid ejection device includes a first unit droplet generator including a first actuator and a first nozzle between a first and a second fluid feed hole, the first fluid feed hole located on a first channel and the second fluid feed hole and a first pump located on a second channel. The example device includes a second unit droplet generator including a second actuator and a second nozzle between a third and a fourth fluid feed hole, the third feed hole located on a third channel and the fourth fluid feed hole and a second pump located on a fourth channel. The first and the second actuators eject fluid at substantially the same backpressure. A first pressure measurable at an inlet of the first channel and the third channel are different from a second pressure measurable at an outlet of the second channel and the fourth channel.

An example recirculation fluid ejection device includes a first unit droplet generator including a first actuator and a first nozzle between a first and a second fluid feed hole, the first fluid feed hole located on a first channel and the second fluid feed hole and a first pump located on a second channel. The example device includes a second unit droplet generator including a second actuator and a second nozzle between a third and a fourth fluid feed hole, the third feed hole located on a third channel and the fourth fluid feed hole and a second pump located on a fourth channel. The first and the second actuators eject fluid at substantially the same backpressure. A first pressure measurable at an inlet of the first channel and the third channel are different from a second pressure measurable at an outlet of the second channel and the fourth channel.

A liquid ejecting device includes a flow path member, an actuator, a pump, and a controller. The flow path member includes a flow path configured to direct flow of a pseudoplastic liquid through the flow path member. The actuator is configured to cause droplets to be ejected. The pump is configured to cause the liquid to flow sequentially through a supply reservoir, a plurality of supply manifolds, a plurality of supply flow paths, and a plurality of pressure chambers. The controller is configured to adjust a flow rate of the liquid to a prescribed target flow rate. The flow path has a flow path shape in which an average viscosity of the liquid in the plurality of supply flow paths is less than or equal to half an average viscosity of the liquid in the plurality of supply manifolds when the flow rate is equal to the target flow rate.

The individual flow path includes a nozzle communicating with an outside, a first flow path, in the middle of which the nozzle is disposed and which extends in a first direction that is an in-plane direction of a nozzle surface of the nozzle plate in which the nozzle opens, a second flow path coupled to the first flow path and extending in a second direction other than the first direction, a third flow path coupled to the second flow path and extending in the third direction other than the second direction, and a pressure chamber which is disposed in the third flow path and in which a pressure change is induced by the energy generating element. A cross-sectional area of the first flow path is smaller than a cross-sectional area of the second flow path.

An inkjet printing apparatus is provided with a tank that stores ink, a print head that performs print operation by ejecting ink supplied from the tank, a circulation unit that establishes a circulating state to circulate ink in a circulation path if print operation is performed and establishes a stopped state to stop circulation of ink if print operation is terminated, and a deaeration unit that performs deaeration operation to deaerate ink inside the circulation path. The apparatus includes an estimation unit that estimates a dissolved gas amount in ink inside the circulation path based on dissolved gas amounts increased in the circulating state and in the stopped state, respectively, and a control unit that causes the deaeration unit to execute deaeration operation after completion of print operation if the dissolved gas amount estimated by the estimation unit exceeds a predetermined threshold.

One example provides a fluidic die including a nozzle layer disposed on a substrate, the nozzle layer having an upper surface opposite the substrate and including a plurality of nozzles formed therein, each nozzle including a fluid chamber and a nozzle orifice extending through the nozzle layer from the upper surface to the fluid chamber. A conductive trace is exposed to the upper surface of the nozzle layer and extends proximate to a portion of the nozzle orifices, an impedance of the conductive trace indicative of a surface condition of the upper surface of the nozzle layer.

A liquid circulating device has: a supply flow path through which a liquid is supplied from a liquid supply source that stores the liquid to a liquid ejecting head that ejects the liquid; a collection flow path through which the liquid collected from the liquid ejecting head is returned to the supply flow path; and a liquid flowing portion that causes the liquid to flow in a circulation flow path including the supply flow path, the liquid ejecting head, and the collection flow path. An air capturing portion can capture bubbles and is provided in at least one of the supply flow path and collection flow path. The air capturing portion is disposed at a position higher than the position of the liquid ejecting head.