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 plurality of wall surfaces that constitute inner walls of the pressure compartment includes a surface of the recessed portion and the first wall surface, and an angle formed by the first surface and the first wall surface is greater than 90° and less than 180°.

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 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.

A piezoelectric device includes a substrate on which a plurality of recesses are arranged in a first direction, a vibration plate, and a piezoelectric actuator having a first electrode, a second electrode and a third electrode, a fourth electrode, and a piezoelectric layer, in which a plurality of active portions are provided, the second electrode and the third electrode are provided from an edge of a region facing a recess to an outside of the recess, the first electrode is formed between the second electrode and the third electrode, the second electrode, the third electrode, and the fourth electrode configure common electrodes for the plurality of active portions, and the first electrode configures an individual electrode provided independently for each of the active portions.

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.

A MEMS device includes a first substrate 22 including a single-crystal silicon substrate and a second substrate 23 including a single-crystal silicon substrate, in which the first substrate 22 and the second substrate 23 are laminated together, and the first substrate 22 and the second substrate 23 are joined to each other such that the cleavage directions of both substrates intersect each other.

The interface region may include a region in which first intensity is higher than second intensity and in which the first intensity is higher than third intensity, where a degree of orientation of the (−211) crystal face of the second layer is denoted as the first intensity, the degree of orientation of the (−111) crystal face of the second layer is denoted as the second intensity, and the degree of orientation of the (002) crystal face of the second layer is denoted as the third intensity. The surface-layer region may include a region in which the first intensity is higher than the third intensity and in which the second intensity is higher than the third intensity.

A liquid discharge head unit includes a liquid discharge head that has a first detection resistor that is provided to correspond to a first piezoelectric element group, a second detection resistor that is provided to correspond to a second piezoelectric element group, a power supply circuit that causes a current to flow through the first detection resistor and the second detection resistor, a voltage detection circuit that detects a voltage, and a switching circuit that is configured to switch between a first state in which the voltage detection circuit is configured to detect a voltage generated in the first detection resistor due to the current flowing from the power supply circuit and a second state in which the voltage detection circuit is configured to detect a voltage generated in the second detection resistor due to the current flowing from the power supply circuit.

A liquid discharge head includes a pressure chamber substrate that has a plurality of pressure chambers, a piezoelectric element that is laminated at the pressure chamber substrate, and has an individual electrode individually provided for each of the plurality of pressure chambers, a common electrode commonly provided for the plurality of pressure chambers, and a piezoelectric body provided between the individual electrode and the common electrode in a lamination direction of the piezoelectric element and provided to apply pressure to a liquid in the pressure chamber, a drive wiring that is electrically coupled to the individual electrode and the common electrode, and provided to apply a voltage for driving the piezoelectric body to the piezoelectric body, and a heating resistor that is formed of the same material as any of the individual electrode, the common electrode, and the drive wiring, and provided to heat the liquid in the pressure chamber.