the first nozzle channel includes a first portion including an end of the first nozzle channel and a second portion including another end of the first nozzle channel, and a width of the second portion in the second direction is larger than a width of the first portion in the second direction.

A liquid ejection head includes a recording element substrate, a flow path member having a common supply flow path and a common collection flow path through which a liquid having a temperature higher than a temperature of the common supply flow path flows, and a support member supporting the flow path member. The common supply flow path and the common collection flow path are formed to extend along a longitudinal direction of the flow path member and be arranged side by side with each other in a lateral direction of the flow path member. The positions of the flow path member in the longitudinal direction and in the lateral direction are defined at a center portion in the longitudinal direction, and at a side surface located on the common supply flow path side in the lateral direction, among side surfaces extending in the longitudinal direction, respectively.

the first nozzle channel includes a first portion including an end of the first nozzle channel and a second portion including another end of the first nozzle channel, and a width of the second portion in the second direction is larger than a width of the first portion in the second direction.

A liquid discharge head includes a substrate, pressure chambers, a pressure generating element, a discharge port, and a liquid channel. First and second communication supply channels and first and second communication collecting channels are formed in the substrate. A central axis of a first communication supply opening is located closer to the corresponding pressure chamber than a central axis of a first common supply opening, or a central axis of a second communication supply opening is located closer to the corresponding pressure chamber than a central axis of a second common supply opening, or a central axis of a first communication collecting opening is located closer to the corresponding pressure chamber than a central axis of a first common collecting opening, or a central axis of a second communication collecting opening is located closer to the corresponding pressure chamber than a central axis of a second common collecting opening.

A liquid discharge head includes a nozzle from which a liquid is discharged, a pressure chamber communicating with the nozzle, to which the liquid is supplied, a dummy channel not communicating with the nozzle and adjacent to the pressure chamber, the dummy channel being a sealed place to which the liquid is not supplied, and a diaphragm configured to define a displaceable wall of the pressure chamber and a wall of the dummy channel. The wall of the dummy channel defined by the diaphragm includes a through hole.

Long-term reliability of a liquid ejection head substrate and a liquid ejection head is improved by suppressing dissolution of an intermediate layer due to anodization. A liquid ejection head substrate including: a flow passage forming member having an ejection orifice and a flow passage; a heating resistance element for ejecting a liquid; an insulating layer covering the heating resistance element; a protecting layer whose surface is exposed to the flow passage; and an intermediate layer provided between the flow passage forming member and the protecting layer, in which the intermediate layer contains a material represented by a following composition formula (I): Si.sub.w1O.sub.x1C.sub.y1 (I), 39≤w1≤62 (at. %), 32≤x1≤55 (at. %), and 6≤y1≤29 (at. %), and w1+x1+y1=100 (at %).

A liquid discharge head includes: a substrate; pressure chambers provided on a surface of the substrate and through which a first liquid and a second liquid flow; a pressure generating element configured to pressurize the first liquid; and a discharge port communicating with at least one pressure chamber and through which the second liquid is discharged. First and second supply channels, first and second collecting channels, third and fourth supply channels, and third and fourth collecting channels are formed on the substrate. A common channel is formed between a first pressure chamber row and a second pressure chamber row. The common channel communicates with the first supply channel and the third supply channel, or communicates with the second supply channel and the fourth supply channel, or communicates with the first collecting channel and the third collecting channel, or communicates with the second collecting channel and the fourth collecting channel.

A liquid ejection head unit includes a first energy generating element that generates energy that applies pressure to a liquid in the first pressure chamber; a second energy generating element that generates energy that applies pressure to a liquid in the second pressure chamber; a nozzle flow path which communicates the first pressure chamber and the second pressure chamber and in which a nozzle that ejects a liquid is provided; a drive circuit that drives the first energy generating element and the second energy generating element by applying a drive pulse; a detection circuit that detects a parameter related to a physical property of a liquid in the second pressure chamber; wherein a controller drives the first energy generating element by the drive circuit, and performs a first detection operation of detecting the parameter in the second pressure chamber by the detection circuit.

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.

In a liquid ejection head, an ejection pressure is applied to a pressure chamber for liquid ejection from a nozzle. A descender extends in a first direction and includes a first end connected to the pressure chamber and a second end. A communication passage is connected to the second end, extends in a second direction crossing the first direction, and has a first dimension in the first direction. The nozzle is positioned at the communication passage such that a shortest distance between an outer periphery thereof and a center of the second end is greater than 0.5 times a second dimension of the second end in the second direction. When viewed in the first direction, the center of the second end and a center of a cross-section defined by the nozzle to be orthogonal to an extending direction of the nozzle intersect an axis of the communication passage.