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 microfluidic device including a fluid ejection channel defined by a fluid barrier and an orifice, or nozzle, for containing and/or passing fluids, and further including micro-electromechanical systems (MEMS) and/or electronic circuitry may be fabricated on a silicon substrate and included in a fluid ejection system. Various microfabrication techniques used for fabricating semiconductor devices may be used to manufacture such microfluidic devices.

There is provided a liquid discharge head, including: a channel unit; a vibration film; and piezoelectric elements. Pressure chambers form pressure chamber pairs arranged in a second direction. Each of the pressure chamber pairs includes a first pressure chamber and a second pressure chamber that communicate with an identical nozzle via a communication channel Rigidity of a first partition wall separating the first pressure chamber from the second pressure chamber, the first and second pressure chambers being included in each of the pressure chamber pairs, is different from rigidity of a second partition wall separating the first pressure chamber from the second pressure chamber, the first and second pressure chambers being adjacent to each other in the second direction and included in different pressure chamber pairs included in the pressure chamber pairs.

A fluid ejection die includes a fluid slot, laterally adjacent fluid ejection chambers each communicated with the fluid slot and having respective drop ejecting elements therein, and orifices each communicated with a respective one of the laterally adjacent fluid ejection chambers. The laterally adjacent fluid ejection chambers are spaced substantially a same distance from the fluid slot along a same side of the fluid slot, and the orifices communicated with the laterally adjacent fluid ejection chambers are spaced different distances from the fluid slot.

An element substrate is bonded to a support substrate with high positional accuracy. A manufacturing method of the liquid ejecting head includes curing a first adhesive, which is in contact with an element substrate and a support substrate, at a first temperature to perform first temporary fixing, heating a second adhesive, which is in contact with the element substrate and the support substrate, to a second temperature higher than the first temperature so as to cure the second adhesive and perform second temporary fixing and heating a third adhesive, which is in contact with the element substrate and the support substrate, to a third temperature higher than the second temperature so as to cure the third adhesive and bond the element substrate to the support substrate. An elastic modulus of the second adhesive is larger than an elastic modulus of the first adhesive at the second temperature.

A liquid ejection head includes a print element substrate including multiple ejection openings, pressure chambers, a common flow path, and pumps, the pumps being configured to circulate liquid between the common flow path and the pressure chamber; and a flow path member laminated to the print element substrate. The flow path member includes a supply flow path and a collection flow path, the supply flow path being configured to supply liquid to the print element substrate, and the collection flow path being configured to collect liquid that is not ejected. The supply flow path and the collection flow path have liquid connection with the same common flow path. A circulating pump generates a flow of liquid flowing in an order of the supply flow path, the common flow path, and the collection flow path, the circulating pump being provided at a position different from the print element substrate.

A fluid ejection device may include fluid actuators, ejection chambers adjacent the fluid actuators, nozzles extending from the ejection chambers, and fluid feed holes to supply fluid from a fluid supply passage to the ejection chambers. The fluid feed holes have ports connected to the ejection chambers. The ports are sized to pass bubbles formed by the fluid actuators out of the ejection chambers.

A printing apparatus includes: a tank configured to contain ink; a print head configured to eject ink supplied from the tank; a supply flow path through which liquid is supplied from the tank to the print head; a collection flow path through which liquid is collected from the print head to the tank; a circulation unit configured to circulate ink inside a circulation flow path including the tank, the supply flow path, the print head, and the collection flow path; and a cooling unit configured to cool the tank by blowing.

A liquid discharge head includes a discharge port member including a discharge port, a flow path member including a pressure chamber and a liquid flow path, a substrate, and a structure that is arranged on the substrate on an upstream side of a center of the discharge port and that is configured to generate a flow of the liquid toward the discharge port. The liquid in the pressure chamber circulates. A position corresponding to a portion of the structure having a greatest height from a surface of the substrate is located on the upstream side of the center of the discharge port in a flow direction of the liquid. A thickness of the structure in a discharge direction of the liquid is 0.1 times or greater than a thickness of the liquid flow path in the discharge direction of the liquid.

In a liquid ejection head, a substrate is provided with a first inflow port located on an upstream side of a pressure chamber with respect to a direction of flow of liquids in a liquid flow passage and configured to allow a first liquid to flow into the liquid flow passage, a second inflow port located on the upstream side of the first inflow port and configured to allow a second liquid to flow into the liquid flow passage, and a lateral wall extending in a direction of extension of the liquid flow passage. At least part of the lateral wall is located above the first inflow port. In the pressure chamber, the first liquid flows in contact with a pressure generating element while the second liquid flows closer to the ejection port than the first liquid does.