Systems and method of maintaining a uniform temperature distribution in an inkjet head. The inkjet head includes a plurality of ink channels that jet droplets of a liquid material onto a medium using piezoelectric actuators. A temperature controller includes a non-jetting pulse generator that provides non-jetting pulses to one or more of the piezoelectric actuators to generate heat. The non-jetting pulses cause the the piezoelectric actuators to actuate without jetting a droplet from its corresponding ink channel.

A liquid discharge head includes a nozzle to discharge a liquid, an individual chamber communicating with the nozzle, a supply channel communicating with the individual chamber to supply the liquid to the individual chamber, and a discharge channel communicating with the individual chamber to discharge the liquid in the individual chamber. A fluid resistance of the supply channel is greater than a fluid resistance of the discharge channel.

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 piezoelectric printing device includes a substrate and a piezoelectric plate. A pair of staggered rows of drop ejectors is disposed along a row direction on the substrate. Each drop ejector includes a nozzle in fluid communication with a pressure chamber that is bounded by side walls. The piezoelectric plate has a first surface that is proximate to the pressure chambers. An electrode layer is disposed on an opposing outer second surface of the piezoelectric plate. The electrode layer includes a signal line corresponding to each drop ejector in the pair of staggered rows, and at least one common ground bus connected to ground traces that are aligned over the side walls of each pressure chamber. Each signal line leads to a corresponding signal input pad that is disposed between the staggered rows. The common ground bus extends along the row direction and leads to a ground return pad.

A liquid ejection head includes an individual channel, a first manifold, a filter, a second manifold, and a bypass path. The individual channel has a nozzle. The first manifold is in fluid communication with the individual channel. The filter is disposed in the first manifold. The second manifold is in fluid communication with the individual channel. The bypass path is positioned across the filter from the individual channel with respect to a direction perpendicular to a surface extending direction of the filter. The bypass path provides fluid communication between the first manifold and the second manifold not via the individual channel.

A piezoelectric printhead includes a piezoelectric printing device, a manifold, a U-shaped flexible printed wiring element and an interconnection element. The piezoelectric printing device includes a piezoelectric plate and a substrate with at least one row of drop ejectors; an ink inlet port; signal lines leading to corresponding signal input pads; and ground traces leading to at least one ground return pad. The manifold is fluidically connected to the ink inlet port. The U-shaped flexible printed wiring element includes a device connection region and a pair of legs that extend from the device connection region. The pair of legs includes signal connection lines and at least one ground connection line. The interconnection element is disposed between the device connection region of the U-shaped flexible printing wiring element and a contact layer of the piezoelectric printing device that includes the signal input pads and the at least one ground return pad.

A fluid recirculation channel for dispensing a plurality of fluid drop weights includes a number of sub-channels. The sub-channels include at least one pump channel, and a plurality of drop generator channels fluidically coupled to the at least one pump channel. The fluid recirculation channel further includes a number of pump generators incorporated into the at least one pump channel, a number of drop generators incorporated into drop generator channels, and a plurality of nozzles defined within the drop generator channels, the nozzles being at least as numerous as the number of drop generators.

A liquid discharging head includes a nozzle plate having a plurality of nozzles from which liquid is discharged; a plurality of individual liquid chambers that are communicably connected to the plurality of nozzles, respectively; a common liquid chamber that supplies liquid to the plurality of individual liquid chambers; and a circulation common liquid chamber that leads to a plurality of circulation channels. A part of the common liquid chamber overlaps the circulation common liquid chamber from a direction in which liquid is discharged from the nozzles, and another part of the common liquid chamber overlaps the circulation common liquid chamber from a direction orthogonal to both the direction in which liquid is discharged from the nozzles and a direction in which the nozzles are aligned.

A droplet discharging apparatus that discharges liquid droplets from one or more nozzles based on drive waveforms, includes a memory and a processor configured to execute generating, as the drive waveforms, a first drive waveform, and a second drive waveform to change a drive voltage without discharging the liquid droplets; and controlling to output one set of drive waveforms including a predetermined number of instances of the first drive waveform and one instance of the second drive waveform.

Example implementations relate to controllers and printers to operate at least one liquid ejection device of a printhead; the liquid ejection device comprising a nozzle and an associated print liquid chamber bearing a transducer to eject print liquid from the nozzle in response to a firing signal; the print chamber being fluidically coupled to a nozzle supply channel; the at least one liquid ejection device comprising a channel coupled to the print liquid chamber and the nozzle supply channel; the channel having a respective actuator to urge print liquid through the print chamber in response to a circulation signal; wherein the controller comprises temperature control circuitry to actuate the respective actuator using a temperature control signal to increase the temperature of print liquid in the print liquid chamber.