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 actuator includes a common electrode on a piezoelectric layer at a first side adjacent to a first surface and extends over a plurality of piezoelectric elements. A plurality of first individual electrodes is on the piezoelectric layer at a second side adjacent to a second surface. Each of the plurality of first individual electrodes is at a piezoelectric element of the plurality of piezoelectric elements, and are not electrically connected together. A first insulating layer is on the common electrode at the first side and extends over the plurality of piezoelectric elements. A plurality of second individual electrodes is on the first insulating layer at the first side. Each of the plurality of second individual electrodes is at a piezoelectric element of the plurality of piezoelectric elements, and overlap centers of the plurality of first individual electrodes. The plurality of second individual electrodes are electrically connected together.

There is provided liquid discharging head having unit heads. Each of the unit heads includes: first piezoelectric layer, driving electrodes arranged on surface of the first piezoelectric layer and to each of which one of first and second potentials is to be applied, and common electrode. The common electrode includes: potential receiving part configured to receive one of the first and second potentials; and extending part extending in extending direction orthogonal to the first direction, so as to overlap with the driving electrodes in the first direction. The unit heads are arranged so that the common electrodes of the plurality of unit heads are adjacent to each other in second direction orthogonal to the first direction. The extending directions of two of the common electrodes adjacent to each other in the second direction are opposite to each other.

A liquid discharge head includes an individual liquid chamber having a nozzle through which a liquid is discharged in a liquid discharge direction, a piezoelectric element facing the individual liquid chamber, a first groove adjacent to the piezoelectric element in a nozzle array direction, a dummy individual liquid chamber without any nozzle, a dummy piezoelectric element facing the dummy individual liquid chamber, and a second groove adjacent to the dummy piezoelectric element in the nozzle array direction. The first groove extends in the liquid discharge direction. The second groove has a shorter length in the liquid discharge direction than the first groove.

A first active region is made of a piezoelectric overlaps a midsection of a pressure chamber when viewed in plan through a pressure applying surface. A second active region is made of a piezoelectric member closer than the first active region to the pressure applying surface. The second active region extends over both a peripheral section of the pressure chamber and an outer region located outside the pressure chamber when viewed in plan through the pressure applying surface. A driver controls intensity of a first electric field applied to the first active region and intensity of a second electric field applied to the second active region such that the time period over which the first active region contracts and the time period over which the second active region contracts overlap or coincide with each other. The first electric field is more intense than the second electric field.

A piezoelectric actuator array includes a substrate plate with a number of signal leads and at least one common lead, and a number of piezoelectric bodies arranged in a row on one surface of the substrate plate and formed by dividing a common piezoelectric block. The piezoelectric bodies include a number of active bodies each of which has, on a first side of the row, a signal electrode in contact with one of the signal leads and, on an opposite second side of the row, a common electrode in contact with the common lead. The substrate plate has at least one connector lead disposed on the first side of the row and electrically connected to the common lead on the second side of the row. At least one piezoelectric body has a conductive outer surface layer that establishes an electrically conductive path from the connector lead to the common lead.

A head includes the passageway member which is configured by a plurality of plates stacked through the adhesive and in which the ink passageways are configured by communication of the through holes individually formed in the plurality of plates to each other. The plurality of plates includes the resin plate and a plurality of metal plates. The resin plate does not have a relief groove for the adhesive. The plurality of metal plates include the eighth metal plate and/or ninth metal plate which is adhered to the resin plate and includes the relief groove for the adhesive on the resin plate side.

A liquid discharge head is configured to achieve decrease in temperature difference in the liquid discharge head, and includes a recording device including the liquid discharge head. The liquid discharge head includes a channel member having a plurality of discharge holes, a plurality of pressurization chambers, and a plurality of common channels, and a plurality of pressurizing parts. The plurality of common channels extends in a first direction and configures a common channel group aligned in a second direction crossing the first direction, the common channels are connected with the plurality of pressurization chambers disposed along the common channels among the plurality of pressurization chambers, and the channel member is disposed outside, in the second direction, with respect to the common channel group, and further includes a first end channel extending in the first direction, and the first end channel is lower in channel resistance than the common channels.

A printhead module includes a plurality of rows of printhead nozzles, at least some of the rows including at least one displaced row portion, the displacement of the row portion including a component in a direction normal to that of a pagewidth to be printed, wherein the displaced row portions of at least some of the rows are different in length than the displaced row portions of at least some of the other rows.