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 actuator includes a deformable thin-film member having an opening, an electromechanical conversion element disposed at a periphery of the opening of the deformable thin-film member, an insulating film covering the electromechanical conversion element, a protective film over a surface of the insulating film, the protective film covering the surface of the insulating film and a surface of an electrode wiring connected to the electromechanical conversion element, and an adhesion improving film disposed between the electrode wiring and the protective film.

A liquid discharge head attachment device includes a liquid discharge head including a plurality of nozzles that discharges liquid. The liquid discharge head has a nozzle face mounting the nozzles and a side face being perpendicular to the nozzle face. An attachment member is attached with the liquid discharge head. A position adjuster contacts the side face of the liquid discharge head and adjusts a position of the liquid discharge head with respect to the attachment member. The position adjuster is disposed outboard from the nozzles of the liquid discharge head. The position adjuster overlaps the liquid discharge head in an orthogonal direction perpendicular to the nozzle face of the liquid discharge head in at least a part of the position adjuster.

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, and the fourth electrode configures a common electrode for the plurality of active portions.

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.

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.

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.

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.

A bonding substrate is provided with nozzle communication channels that establish communication between pressure chambers and nozzles. Each nozzle communication channel includes a pair of first inner wall surfaces constituting wall surfaces in a first direction, and a pair of second inner wall surfaces constituting wall surfaces in a second direction being orthogonal to the first direction. At least one of the second inner wall surfaces includes an inclined surface being inclined such that a length of the nozzle communication channel becomes gradually shorter toward the nozzle. An angle of the inclined surface relative to a liquid ejecting surface where the nozzles are opened is smaller than an angle of the first inner wall surface relative to the liquid ejecting surface.