A fluid ejection and circulation apparatus may include a fluid ejection die, the pressure regulator, a first standpipe, a second standpipe and a crossflow passage. The pressure regulator has a fluid chamber. The first standpipe is between the fluid chamber and the fluid ejection die. The first standpipe has a first port above the fluid ejection die. The second standpipe extends alongside the first standpipe. The second standpipe has a second port above the fluid ejection die. The crossflow passage connects the first standpipe and the second standpipe.

In one example in accordance with the present disclosure, a fluid ejection device is described. The fluid ejection device includes a number of nozzles to eject fluid. Each nozzle includes a firing chamber to hold fluid, a nozzle orifice through which to dispense fluid, and an ejector disposed in the firing chamber to eject fluid through the nozzle orifice. The fluid ejection device also includes a particle detector to detect the presence of foreign particles within the fluid in the firing chamber.

In one example in accordance with the present disclosure, a fluid ejection device is described. The fluid ejection device includes a number of nozzles to eject fluid. Each nozzle includes a firing chamber to hold fluid, a nozzle orifice through which to dispense fluid, and an ejector disposed in the firing chamber to eject fluid through the nozzle orifice. The fluid ejection device also includes a particle detector to detect the presence of foreign particles within the fluid in the firing chamber.

A fluidic die may include at least one fluidic passageway, at least one electrode disposed within the at least one fluidic passageway, and control circuitry to activate the electrode within the fluidic die. An impedance sensed at the electrode corresponds to a particle concentration within the fluid. The control circuitry activates the electrode during a separate pulse group assigned to the activation of the electrode among at least one other pulse group assigned to an activation of at least one fluid actuator within a column group.

Density of each pixel is specified from a test pattern for measurement of density distribution, a density profile indicating distribution of the specified density for each pixel is acquired, and a pixel region including a nozzle of interest having a certain density difference or more from surrounding pixels and pixels on both sides thereof is extracted as a nozzle region of interest from the acquired density profile. Filters B to E, other than a filter A to be applied for density smoothing processing of pixels that do not belong to the nozzle region of interest, are applied for the density smoothing processing of the pixels in the nozzle region of interest, to generate a profile of a density correction value for eliminating a density difference between respective pixels based on the density profile after the smoothing processing.

A fluid ejection device may include fluid actuators and an actuation controller. Each fluid actuator may have an associated address. The actuation controller is to receive an address for a fluid actuator of the device to be actuated and is further to automatically transmit one of different fire pulses based upon the received address.

A fluid ejection device may include fluid actuators and an actuation controller. Each fluid actuator may have an associated address. The actuation controller is to receive an address for a fluid actuator of the device to be actuated and is further to automatically transmit one of different fire pulses based upon the received address.

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.

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.

A print head of a continuous ink jet printer, including, in a cover: means for producing at least one ink jet; means for separating drops of jets intended for printing from those that do not serve for printing; a slot, enabling drops intended for printing to get out; a recovery gutter (7) for drops not intended for printing, the recovery gutter comprising an ink recovery volume (12); at least one detection conductor (20), arranged inside the head; means (16) for detecting a variation in impedance of at least one of the detection conductors when ink (21) is present in contact with the conductor or with a dielectric layer (22) in contact therewith.