A print head has an ink slot and a sensing chamber having a first port connected to the fluid slot and a second port. The sensing chamber contains an ink level sensor. A recirculation passage extends from the fluid slot and is fluidly coupled to the second port. A fluid pump circulates fluid through the recirculation passage.

A fluid ejection device includes a fluid slot, at least one fluid ejection chamber communicated with the fluid slot, a drop ejecting element within the at least one fluid ejection chamber, a fluid circulation channel communicated with the fluid slot and the at least one fluid ejection chamber, and a fluid circulating element communicated with the fluid circulation channel. The fluid circulating element is to provide on-demand circulation of fluid from the fluid slot through the fluid circulation channel and the at least one fluid ejection chamber.

Printheads and methods for forming printheads are described herein. In one example, a printhead includes a number of drop generators, wherein a pitch between each adjacent drop generator is substantially the same, and the drop generators alternate between a high drop weight (HDW) drop generator and a low drop weight (LDW) drop generator. The printhead also includes a flow channel from an ink source leading into an ejection chamber associated with each drop generator, wherein the flow channel comprises an inflow region proximate to the ink source, wherein an area of the inflow region is adjusted to control the flux of ink into the ejection chamber.

A fluid ejection device includes a fluid slot, a plurality of fluid ejection chambers communicated with the fluid slot, a plurality of drop ejecting elements one of each within one of the fluid ejection chambers, a fluid circulation channel communicated with the fluid slot and one or more of the fluid ejection chambers, and a fluid circulating element communicated with the fluid circulation channel. The fluid circulating element is to provide continuous circulation of fluid from the fluid slot through the fluid circulation channel and the one or more of the fluid ejection chambers.

Printheads and printers are described herein. In one example, a printhead includes a plurality of nozzles configured to eject ink drops of different sizes wherein a low drop weight (LDW) drop is ejected through a nozzle with a circular bore (CB), and a high drop weight (HDW) drop is ejected through a nozzle with a non-circular bore (NCB).

A recording element substrate includes: a substrate on which a plurality of energy generating elements that generate energy used for ejecting liquid are arranged side by side, an ejection port forming member in which ejection ports are formed at positions corresponding to the plurality of energy generating elements, a plurality of supply passages which are channels extending in a thickness direction of the substrate and through which liquid is supplied to the energy generating elements, and a support member that is formed between the substrate and the ejection port forming member and supports the ejection port forming member, in which supply ports that are apertures of the plurality of supply passages are linearly arranged side by side on the substrate, and a plurality of support members are provided side by side between adjacent supply ports on the substrate in a direction in which the supply ports are aligned.

A liquid ejection head has: a frame having a plurality of ejection ports for ejecting a liquid; a common liquid chamber; a plurality of individual liquid chambers through which the common liquid chamber communicates with each of the ejection ports; and a plurality of energy generating elements disposed in respective individual liquid chambers. A part of a wall of the frame that forms the common liquid chamber is formed of an elastic member capable of deforming elastically, so that a volume of the common liquid chamber can be modified.

An apparatus includes a pipette dispenser to control dispensing of a volume to a dispensing location. A tip is operatively coupled to the pipette dispenser. The tip includes an electromechanical print head to dispense the volume from the pipette dispenser to the dispensing location based on a command from the pipette dispenser that indicates an amount of the volume to be dispensed from the print head.

A liquid discharge head includes: a substrate, where a recording element is disposed; and a discharge orifice forming member, where a discharge orifice, facing the recording element, and configured to discharge the liquid, is formed. The liquid discharge head has a pressure chamber, a first liquid channel configured to supply liquid to the pressure chamber, and a second liquid channel configured to recover liquid from the pressure chamber. The substrate has a liquid supply channel connected to the first liquid channel to supply liquid to the first liquid channel, and a liquid recovery channel connected to the second liquid channel, to recover liquid from the second liquid channel. Pressure at an inlet portion of the liquid supply channel is higher than pressure at an outlet portion of the liquid recovery channel, and a flow velocity of liquid within the pressure chamber is 3 to 140 mm/s.

A method for manufacturing a liquid ejection head includes the steps of: preparing a substrate including an energy-generating element disposed on a first surface of the substrate and a supply path for liquid; disposing a dry film on the first surface of the substrate in such a manner that the dry film partially enters the supply path; etching the dry film from a side of the dry film facing the first surface of the substrate so that the dry film has an etched surface substantially in parallel with the first surface and covers the supply path; forming a resin layer to be a flow path member on the dry film covering the supply path; and removing the dry film covering the supply path.