In a substrate, a first flow channel opened in a first surface of a silicon base material having a crystal orientation of <110>, and a second flow channel opened in a second surface of the silicon base material opposite the first surface are formed to communicate with each other. The second flow channel has an opening width narrower than an opening width of the first flow channel, and a groove portion shallower than a depth of the second flow channel is formed close to the opening of the second flow channel in a region that is inside the opening of the first flow channel and outside the opening of the second flow channel in the second surface.

In a case where air bubbles exist in ink at the time of circulating the ink within a liquid ejection module, the amount circulating ink runs short and stability of ejection is blocked. The liquid ejection module has: a pressure chamber that communicates with an ejection port and which stores a liquid; an energy generation element that produces energy for causing a liquid to be ejected from the ejection port; a supply flow path that supplies a liquid to the pressure chamber; a collecting channel that collects a liquid from the pressure chamber; a liquid sending chamber that connects to the collecting channel; a connection flow path that connects the liquid sending chamber and the supply flow path; and a liquid sending unit configured to circulate a liquid, and the liquid sending chamber has a continuously inclined structure.

A fluid ejection die may include a fluid actuator, a substrate supporting the fluid actuator, a chamber layer supported by the substrate and a bypass passage in the substrate. The substrate may include a closed inlet channel having an inlet opening for connection to an outlet of a fluid source and an outlet channel having an outlet opening of a first size for connection to an inlet of the fluid source. The chamber layer includes a recirculation passage to supply fluid for ejection by the fluid actuator through an ejection orifice and to circulate fluid across the fluid actuator from the closed inlet channel to the outlet channel. The bypass passage is of a second size less than the first size and connects the inlet channel to the inlet of the fluid source while bypassing any fluid actuator provided for ejecting fluid through an ejection orifice.

An aspect of the present invention is a liquid ejection apparatus including: a liquid ejection head including a heating element, a first protection layer, a second protection layer that functions as a first electrode, a second electrode that is electrically connected to the first electrode, and an ejection port; and a control unit configured to perform control of setting a potential difference between potentials of the first and second electrodes to a predetermined value by changing at least one of the potentials of the first electrode and the second electrode, in which the control unit sets the potential difference to a first value in a case where printing is performed, and the control unit sets the potential difference to a second value different from the first value and feeds power to at least one of a plurality of the heating elements in a case where printing is not performed.

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 liquid ejection head has at least a structure including an ejection orifice forming member having an ejection orifice for ejecting a liquid and a flow path communicating with the ejection orifice and a flow path forming substrate having a liquid introduction flow path communicating with the flow path and supplying the liquid, and includes: a first titanium oxide film with a pure water contact angle of 40° or less; and a second titanium oxide film with a pure water contact angle of 70° or more, wherein the first titanium oxide film covers the structure including inner walls of the flow path and the liquid introduction flow path and is exposed in the flow path and the liquid introduction flow path, and the second titanium oxide film has a portion covering the first titanium oxide film in a vicinity of an opening end.

A liquid ejection apparatus includes: an ejection unit that ejects from an ejection port a liquid in a pressure chamber communicating with the ejection port; a first flow channel that allows for communication between the pressure chamber and a liquid supply unit; a second flow channel communicating with the pressure chamber; a liquid transportation chamber communicating with a connection flow channel communicating with the first flow channel and the second flow channel; a liquid transportation unit that flows the liquid in the liquid transportation chamber in a predetermined direction by expanding and contracting the liquid transportation chamber with application of a driving voltage including a step-up waveform and a step-down waveform; and a control unit that performs control such that a liquid ejection timing does not coincide with a voltage application period in which one of the step-up and step-down waveforms that has a greater voltage change rate is applied.

A fluid ejection die includes an ejection nozzle and an ejection chamber fluidly connected to the ejection nozzle. The die includes a fluid input hole fluidly connected to the ejection chamber, a fluid output hole, and a fluid output channel fluidly connected to the ejection chamber and the fluid output hole. The die includes a fluid circulation rib positioned between the fluid input hole and the fluid output hole.

An object is to provide a liquid ejection apparatus and a method of controlling a liquid ejection apparatus capable of preventing bubbles generated by kogation removal from interfering with the kogation removal. To this end, in a long liquid ejection head with a liquid circulated therethough, a pressure chamber is pressurized and a voltage is applied to a heat applying portion and an electrode to perform kogation removing cleaning.

An example printing fluid pen comprises a plurality of fluid ports, including an inlet port to direct fluid from a fluid reservoir to a fluid ejection device, and a recirculation port to direct fluid from the fluid ejection device out of the inkjet pen. The example pen also includes a plurality of parallel fluid pressure regulators fluidly coupled with the inlet port, each of the plurality of parallel fluid pressure regulators to receive fluid from the inlet fluid port.