A liquid discharge head comprising a substrate comprising a liquid feeding port and an energy generating element for liquid discharge, and a flow channel member comprising, on the substrate, a discharge port through which a liquid is discharged and a liquid flow channel communicating with both the liquid feeding port and the discharge port, wherein the flow channel member comprises a flow channel member (1) not comprising a surface in contact with the liquid and a flow channel member (2) comprising a surface in contact with the liquid, a film stress S.sub.1 and S.sub.2 of the flow channel members (1) and (2), respectively, satisfy S.sub.1<S.sub.2, a film thickness L.sub.1 and L.sub.2 of the flow channel member (1) and (2), respectively, in a direction perpendicular to the substrate, satisfy L.sub.1<L.sub.2, and satisfying 470 MPa.Math.μm<[L.sub.1×S.sub.1+(L.sub.2−L.sub.1)×S.sub.2]<1200 MPa.Math.μm.

when one position where a distance in the second direction to the partition wall located at a nearest position in the second direction is long is assumed as a first position, and the other position where the distance is short is assumed as a second position, both the piezoelectric body and the vibration plate are provided at the first position and the second position, and a thickness of the vibration plate at the second position is smaller than a thickness of the vibration plate at the first position.

A method for manufacturing a piezoelectric actuator is disclosed that includes forming a vibration plate, forming a plurality of electrodes on the vibration plate, forming a piezoelectric layer on the electrodes, and forming a common electrode on the piezoelectric layer.

A first inflow port allows a first liquid to flow into a liquid flow passage, and a second inflow port allows a second liquid to flow into the liquid flow passage. The first and second liquids flow toward a pressure chamber. There is a portion satisfying L≥W, where L is a length of the first inflow port and W is a length of the liquid flow passage above the first inflow port, in a direction orthogonal to a direction of flow of the first liquid in the pressure chamber and to a direction of ejection of the second liquid from an ejection port. In a case where the second liquid is ejected from bottom to top, the second liquid flows above the first liquid.

There is provided a liquid discharge head, including: a piezoelectric body having a plurality of piezoelectric layers stacked on top of each other in a stacking direction; individual electrodes; and a first common electrode. Each of the individual electrodes has a first portion and a second portion arranged in the first direction at an interval, and a third portion coupling the first portion with the second portion. The first common electrode includes a first extending portion as well as first protrusions and second protrusions protruding from the first extending portion. Portions of the first extending portion overlapping in the stacking direction with the third portions are formed having through holes passing through the first common electrode in the stacking direction.

There is provided a liquid discharge apparatus including: a discharging member including a plurality of individual electrodes arranged side by side in a first direction, a plurality of individual channels arranged side by side in the first direction, a plurality of nozzles arranged side by side in the first direction, a common channel communicating with the plurality of individual channels, and an opening communicating with the common channel; and a heating member at least a part of which makes contact with the discharging member. An individual electrode, included in the plurality of individual electrodes and located at an end in the first direction, and the opening are apart from each other in the first direction. At least the part of the heating member is a part making contact with the discharging member, at a location between the opening and the individual electrode located at the end in the first direction.

A liquid discharge head includes first and second actuators and a drive circuit. Each of the first and second actuators is configured to expand and contract first and second pressure chambers, respectively. The drive circuit is configured to, during a dot formation cycle apply a first number of discharge pulses to the first actuator to cause the first number of droplets to be discharged from the first pressure chamber and apply a second number of discharge pulses to the second actuator to cause the second number of droplets to be discharged from the second pressure chamber and apply a third number of precursors to the second actuator. The first number is greater than or equal to two. Each of the second and third numbers is greater than or equal to one. A sum of the second and third numbers is less than or equal to the first number.

A piezoelectric actuator is provided, including a vibration plate, a piezoelectric layer, a plurality of individual electrodes arranged in two arrays, first and second common electrodes which have first and second facing portions facing parts of the individual electrodes and first and second connecting portions connecting the first and second facing portions respectively, and first and second wiring portions which are arranged on the vibration plate and which are connected to the first and second common electrodes respectively via first and second connecting wirings, wherein one of the first connecting wirings connects the first connecting portion and one of the first wiring portion while striding over the second connecting portion.

A piezoelectric thin film element having a first electrode, a second electrode and a piezoelectric thin film between the electrodes, wherein the thin film comprises a laminate having two or more piezoelectric thin film layers and wherein a first thin film layer is doped by one or more dopants and a second film layer is doped by one or more dopants and wherein at least one dopant of the second thin film layer is different from the dopant or dopants of the first thin film layer.

A liquid ejecting head includes: a substrate; a first electrode; a piezoelectric layer covering the first electrode; a second electrode positioned on the piezoelectric layer; a plurality of pressure chambers arrayed in a first direction; and a rigid layer. Each pressure chamber has one end portion and another end portion in a second direction. The rigid layer has an edge providing a plurality of convex parts and a plurality of concave parts. Each convex part and each concave part are alternately arrayed with each other in the first direction. Each convex part is positioned outside each pressure chamber and protrudes in the second direction toward the another end portion. Each concave part is positioned at each pressure chamber and is concaved in the second direction away from the another end portion.