In some examples, a controller receives impedance sensor values from an impedance sensor in a printhead, determines whether the impedance sensor values correlate to a production of an effective drive bubble for the printhead, and issues a command to modify a firing parameter for a fluid ejector of the printhead based on the impedance sensor values.

Examples associated with drop velocity aberrancy detection are disclosed. One example includes firing ink through nozzles of a print-head past sensors to identify drop velocities of the nozzles. A target drop velocity is selected based on the drop velocities of the nozzles. An aberrant nozzles is detected when a nozzle has a drop velocity that deviates from the target drop velocity by a selected threshold. The aberrant nozzle is deactivated, and a good nozzle that will travel over locations traversed by the aberrant nozzle is configured to print portions of a job that would have been printed by the aberrant nozzle.

Examples associated with drop velocity aberrancy detection are disclosed. One example includes firing ink through nozzles of a print-head past sensors to identify drop velocities of the nozzles. A target drop velocity is selected based on the drop velocities of the nozzles. An aberrant nozzles is detected when a nozzle has a drop velocity that deviates from the target drop velocity by a selected threshold. The aberrant nozzle is deactivated, and a good nozzle that will travel over locations traversed by the aberrant nozzle is configured to print portions of a job that would have been printed by the aberrant nozzle.

In some examples, a printhead includes a firing chamber to receive printer fluid, an ejector positioned in the firing chamber to eject printer fluid droplets from the printhead, and a nozzle in fluid communication with the firing chamber. The printhead can further include an impedance sensor positioned in the firing chamber to contact printer fluid to measure impedance values of the printer fluid. The impedance sensor can be connectable to a controller to transmit impedance values of printer fluid to the controller.

A method for delivering a predetermined amount of fluid from a fluid ejection head. The method includes measuring one or more parameters selected from fluid flow parameters and electrical parameters for the fluid ejection head to provide one or more measured parameters; calculating a fluid ejection offset value from the one or more measured parameters; storing the fluid ejection offset value in a memory location on the fluid ejection head; accessing the fluid ejection offset value by an ejection head controller; and adjusting an amount of fluid ejected from the fluid ejection head during a fluid ejection step using the fluid ejection offset value to provide the predetermined amount of fluid from the fluid ejection head.

An ink set including a first ink containing a pigment and a water-soluble resin having an anionic group, a second ink containing substantially no pigment and a reactive component, and a third ink containing a polymer emulsion and a water-soluble resin having an anionic group. The pKa of the reactive component is lower than the pKa of the anionic group of the water-soluble resin in the first ink and higher than the pKa of the anionic group of the water-soluble resin in the third ink.

An ink set including a first ink containing a pigment and a water-soluble resin having an anionic group, a second ink containing substantially no pigment and a reactive component, and a third ink containing a polymer emulsion and a water-soluble resin having an anionic group. The pKa of the reactive component is lower than the pKa of the anionic group of the water-soluble resin in the first ink and higher than the pKa of the anionic group of the water-soluble resin in the third ink.

An aqueous ink for ink jet including a resin particle. The resin particle has a first layer and a second layer in this order from the inside toward the outside of the resin particle. The first layer is formed of a first resin in which the proportion of a unit derived from a cycloaliphatic-group-containing ethylenically unsaturated monomer is 10% by mass or less. The tetrahydrofuran-insoluble fraction of the second layer is 15% by mass or more. The second layer is formed of a second resin having the unit derived from the cycloaliphatic-group-containing ethylenically unsaturated monomer and a unit derived from an ionic-group-containing ethylenically unsaturated monomer. The proportion of the unit derived from the ionic-group-containing ethylenically unsaturated monomer in the second resin is 3% by mass or more to 70% by mass or less.

An aqueous ink for ink jet including a resin particle. The resin particle has a first layer and a second layer in this order from the inside toward the outside of the resin particle. The first layer is formed of a first resin in which the proportion of a unit derived from a cycloaliphatic-group-containing ethylenically unsaturated monomer is 10% by mass or less. The tetrahydrofuran-insoluble fraction of the second layer is 15% by mass or more. The second layer is formed of a second resin having the unit derived from the cycloaliphatic-group-containing ethylenically unsaturated monomer and a unit derived from an ionic-group-containing ethylenically unsaturated monomer. The proportion of the unit derived from the ionic-group-containing ethylenically unsaturated monomer in the second resin is 3% by mass or more to 70% by mass or less.

The present disclosure provides an inkjet printing device includes a first sprayer and a second sprayer; a first alignment unit configured to align the first sprayer to be above a display region of a display substrate; a second alignment unit configured to align the second sprayer to be above a peripheral region of the display substrate, the peripheral region surrounding the display region; a control unit configured to control the first sprayer to spray a solution toward the display region of the display substrate and control the second sprayer to spray a second solvent toward the peripheral region of the display substrate, the solution being obtained by dissolving a film-forming material in a first solvent; and an evaporation unit configured to evaporate the first solvent and the second solvent so as to form a film at the display region of the display substrate.