A liquid ejection head, including: nozzles; and a supply passage through which a liquid is supplied to the nozzles, wherein the supply passage includes (a) a first flow passage and (b) a second flow passage connected to the first flow passage and including two sections that extend in different directions from a connected position at which the first flow passage is connected to the second flow passage, the liquid being supplied to the second flow passage from the first flow passage, wherein the second flow passage has a liquid flow resistance larger in a first section than in a second section, and wherein a protrusion protruding toward the first flow passage is provided on an inner wall surface of the second flow passage facing the first flow passage, for permitting the liquid to more easily flow from the first flow passage into the first section than the second section.

A piezoelectric actuator is disclosed that may include a insulating layer, individual electrodes, a common electrode, and a piezoelectric layer. The common electrode may include divisional electrodes that are connected with one another. The individual electrodes may be disposed between the insulating layer and the piezoelectric layer while the piezoelectric layer may be disposed between the individual electrodes and the common electrode. Further, the divisional electrodes may be configured to face the individual electrodes.

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.

S1 is a sum of the areas of a plurality of individual electrodes formed on a first plane of a piezoelectric body of a liquid discharge head, S2 is an area of a first common electrode formed on a second plane, S3 is an area of a second common electrode formed on a third plane, D1 is a distance between a neutral plane and the first plane in a stacking direction, D2 is the distance between the neutral plane and the second plane in the stacking direction, and D3 is the distance between the neutral plane and the third plane in the stacking direction. Then, D1×S1+D2×S2>D3×S3 is satisfied. The liquid discharge head includes a plurality of conductor layers which are formed on the third plane, without contact with the second common electrode and without contact with each other.

There is provided a liquid discharge head including a piezoelectric body having a plurality of individual electrodes and a first common electrode, and a plurality of conductor layers. The plurality of individual electrodes have first to fourth individual electrode arrays, and the first common electrode has first and second extending portions, a plurality of first projecting portions, and a plurality of second projecting portions. Each of the first projecting portions overlaps partially with one of the plurality of individual electrodes forming the second individual electrode array along the stacking direction, and each of the second projecting portions overlaps partially with one of the plurality of individual electrodes forming the third individual electrode array along the stacking direction. The plurality of conductor layers are formed between the plurality of first projecting portions and the plurality of second projecting portions, without contacting the first common electrode and without contacting each other.

A piezoelectric thin film 3 contains a metal oxide, the metal oxide contains bismuth, potassium, titanium, iron and element M, the element M is at least one of magnesium and nickel, at least a part of the metal oxide is a crystal having a perovskite structure, and a (001) plane, a (110) plane or a (111) plane of the crystal is oriented in a normal direction dn of the surface of the piezoelectric thin film 3.

A method for producing a liquid transport apparatus is disclosed. The liquid transport apparatus includes a pressure chamber plate, a ceramics layer formed on a surface of the pressure chamber plate, a piezoelectric layer formed on the ceramics layer, and an electrode formed on the piezoelectric layer. The ceramics layer is formed by heating an insulating ceramic material at a temperature lower than an annealing temperature of the piezoelectric layer. Accordingly, the atoms of the pressure chamber plate are suppressed from being diffused into the piezoelectric layer.

There is provided liquid discharging head including common liquid chambers each extends along first direction and arranged in second direction orthogonal to the first direction; and individual channels each communicates with one of the common liquid chambers and each has nozzle. The liquid discharging head has first and second ends in the second direction. The common liquid chambers include intermediate common liquid chamber interposed between two of the common liquid chambers and expanded common liquid chamber closest to the first end, length of the expanded common chamber in the second direction being longer than length of the intermediate common chamber in the second direction. The nozzles of the individual channels communicating with the expanded common chamber are positioned on a side of the second end with respect to the expanded common chamber without being positioned on a side of the first end with respect to the expanded common chamber.

Provided is a piezoelectric ceramic composition including a potassium sodium niobate-based perovskite type complex oxide represented by Compositional Formula ABO.sub.3, as a main component. Further, the piezoelectric ceramic composition contains Bi in an A site and Zr in a B site. Further, the piezoelectric ceramic composition includes a segregation portion positioned in a crystal grain. At least one of Zr or Bi is localized in the segregation portion.

There is provided a head including: a piezoelectric layer; a plurality of individual electrodes located below the piezoelectric layer in an up-down direction; a common electrode located below the piezoelectric layer. The plurality of individual electrodes includes: a first individual electrode array including a plurality of first individual electrodes aligned in a first direction; and a second individual electrode array including a plurality of second individual electrodes aligned in the first direction. The common electrode includes: a plurality of first facing portions which are demarcated to correspond to the plurality of first electrodes, respectively; a plurality of second facing portions which are demarcated to correspond to the plurality of second electrodes, respectively; and a connecting portion located between the plurality of first facing portions and the plurality of second facing portions, and connecting the plurality of first facing portions and the plurality of second facing portions.