An aspect of the present disclosure is a liquid ejection apparatus including: a liquid ejection head including a conversion element that generates energy required to eject liquid, a first protection layer that blocks contact between the conversion element and the liquid, a second protection layer that partially covers the first protection layer and functions as a first electrode, a second electrode that is electrically connected to the first electrode through the liquid, and an ejection port that ejects the liquid, and a control unit configured to control a potential difference between the first electrode and the second electrode in printing to a predetermined value by changing at least one of potentials of the first electrode and the second electrode. The control unit sets the potential difference based on at least one of a condition and a configuration of the liquid ejection head.

In some examples, a print cartridge includes a monolithic molding, and a printhead die embedded into a molding. The printhead die has a front surface exposed outside the molding to dispense fluid drops through nozzles and an opposing back surface covered by the molding except at a channel in the molding through which fluid is to pass directly to the back surface. The printhead die also has a nozzle health sensor molded into the molding to detect defective nozzles in the printhead die.

In some examples, a printhead can include a main printer fluid line, a firing chamber in fluid communication with the main printer fluid line to receive printer fluid from the main printer fluid line, and a resistor positioned in the firing chamber. The resistor can, for example, receive an electronic current to cause the resistor to heat up and eject printer fluid droplets from the printhead. The printhead can further include a photolithographically fabricated check valve positioned in the firing chamber. The check valve can, for example, be openable to allow filling of the firing chamber with printer fluid and closeable to at least partially seal the main printer fluid line from printer fluid blowback caused by the resistor.

According to an example, a fluid ejection device may include a membrane including a first column of firing chambers, a second column of firing chambers, and a portioning wall, in which the portioning wall physically separates the first column of firing chambers from the second column of firing chambers. The fluid ejection device may also include a plurality of actuators and a substrate including a respective hole extending through the substrate from each of the firing chambers, in which an actuator of the plurality of actuators is provided in each of the firing chambers.

An example recirculation fluid ejection device includes a first unit droplet generator including a first actuator and a first nozzle between a first and a second fluid feed hole, the first fluid feed hole located on a first channel and the second fluid feed hole and a first pump located on a second channel. The example device includes a second unit droplet generator including a second actuator and a second nozzle between a third and a fourth fluid feed hole, the third feed hole located on a third channel and the fourth fluid feed hole and a second pump located on a fourth channel. The first and the second actuators eject fluid at substantially the same backpressure. A first pressure measurable at an inlet of the first channel and the third channel are different from a second pressure measurable at an outlet of the second channel and the fourth channel.

In example implementations, a printhead die is provided. The printhead die includes a substrate, a chamber layer formed on the substrate, a plurality of printing fluid ejection chambers coupled to opposite sides of the chamber layer and along a length of the chamber layer, and a top hat layer formed on the chamber layer and the plurality of printing fluid ejection chambers. The chamber layer includes a void to store printing fluid. The top hat layer includes an initial unsupported top hat layer portion over the void, wherein the initial unsupported top hat layer portion comprises a first end that is narrower than a second end.

A wafer structure is disclosed and includes a chip substrate and a plurality of inkjet chips. The chip substrate is a silicon substrate which is fabricated by a semiconductor process on a wafer of at least 12 inches. The plurality of inkjet chips include at least one first inkjet chip and at least one second inkjet chip. The plurality of inkjet chips are directly formed on the chip substrate by the semiconductor process, respectively, and diced into the at least one first inkjet chip and the at least one second inkjet chip, to be implemented for inkjet printing.

In one example in accordance with the present disclosure, a fluid ejection die is described. The fluid ejection die includes a fluid feed slot to deliver fluid from a reservoir to an array of ejection chambers fluid connected to the fluid feed slot. Each ejection chamber includes at least one fluid actuator and an opening through which fluid is to be ejected. The fluid ejection die also includes a number of antechambers. An antechamber includes sidewalls that curve inward.

Provided is a liquid ejection head including plural liquid chambers arranged in rows, each liquid chamber being provided with an orifice configured to eject liquid filling the liquid chamber and an ejection energy generating element, wherein the liquid ejection head includes: a liquid supply path that extends in a direction that the plural liquid chambers are arranged and individually communicates with the plural liquid chambers; a direction change flow path that communicates with the liquid supply path and extends in a direction transverse to the liquid supply path; and a common supply flow path that communicates with the direction change flow path and extends in a direction transverse to the direction change flow path, such that the direction change flow path includes a body portion and at least one grooved flow path, which is narrower than the body portion.

Misalignment of printing positions between print heads associated with thermal expansion is reduced without increasing a data processing load. To this end, printing element substrates in a reference head and an adjustment target head are adjusted to a target temperature, and a liquid is circulated through the print element substrates. After thermal expansion of the reference head and the adjustment target head reaches a steady state, a first printing region being a printing region of the reference head and a second printing region being a printing region of the adjustment target head in a longitudinal direction are obtained from an image printed by using all printing elements. Then, used regions to be used for actual printing are set among the printing elements arranged on the reference head and the adjustment target head based on the first printing region and the second printing region.