A method for modifying color density values in a dot-based printing system uses a control unit. The control unit implements the modification of the color density values after a raster image has been created and modifies the number and/or size of print dots to be applied to a printing substrate in order to attain pre-defined color density target values.

According to one embodiment, a liquid ejection device includes a nozzle plate in which nozzles for ejecting liquid are arranged, an actuator, a liquid supply unit, and a drive control unit. The actuator is provided in each of the nozzles. The liquid supply unit communicates with the nozzles. When one of a plurality of nozzles is given attention, the drive control unit gives drive signals to actuators of nozzles adjacent in an X direction and a Y direction, to drive the actuators at a timing shifted by a predetermined amount, such as half of a drive period, from a timing of an actuator of the nozzle given attention.

According to one embodiment, a liquid ejection device includes a nozzle plate, an actuator, a liquid supply unit, a waveform generation circuit, a waveform allocation circuit, and a drive signal output circuit. A plurality of nozzles for ejecting liquid is arranged in the nozzle plate. The actuator is provided in each of the nozzles. The waveform generation circuit generates plural kinds of drive waveforms with different generation start timings. The waveform allocation circuit can set the drive waveform among plural kinds of drive waveforms and the actuator of the nozzle to be allocated. The drive signal output circuit drives the actuator with the allocated drive waveform.

The invention relates to a method for actuating an inkjet print head, comprising at least one printing system having a nozzle on the side of an ink chamber which faces a substrate to be imprinted, and which is delimited at least in areas, preferably in its area facing away from the print substrate, by a diaphragm that is movable away from the ink chamber by electrically actuating a piezo element that is mechanically coupled to the diaphragm, so that ink is drawn into the ink chamber from a reservoir, and the diaphragm is movable into the ink chamber so that an ink drop is ejected from the ink chamber through the nozzle, wherein the printing system made up of the ink chamber, diaphragm, piezo element, and the electronic control system thereof represents an oscillatable structure which, when actuated at high energy, is excited to oscillate at a natural frequency f.sub.res that exhibits resonance; i.e. the oscillation with the period T.sub.res=1/f.sub.res undergoes little or no attenuation, and wherein the brightness of a pixel to be printed is varied in that, for each pixel, a sequence of multiple ink drops is ejectable in succession from the same nozzle at a time interval of T.sub.drop=1/f.sub.drop, and energy is only introduced into the printing system via the actuation signal precisely when an ink drop is actually to be ejected.

According to one embodiment, a driving device includes a head driver configured to generate and apply a driving signal to an actuator for ejecting a liquid from a pressure chamber connected to a nozzle, the driving signal including a contraction pulse, the contraction pulse causing the actuator to contract a volume of the pressure chamber, and end application of the contraction pulse when a flow rate of the liquid from the nozzle has a negative value in a liquid ejection direction from the nozzle.

A print head capable of forming dots on a print medium based on print data and a print medium are caused to perform relative movement in a specified direction, and a speed of the relative movement is set according to the number of dots to be formed in an area of a specified size. Whether to set the speed of the relative movement to a first speed is determined according to the number of dots to be formed in an area of a first size on the print medium. Whether to set the speed of the relative movement to a second speed lower than the first speed is determined according to the number of dots to be formed in an area of a second size which is smaller than the area of the first size in the specified direction.

A drop-on-demand printing method comprising performing the following steps in a printing head: discharging a first primary drop (x21A) of a first liquid to move along a first path; discharging a second primary drop (x21B) of a second liquid to move along a second path; controlling the flight of the first primary drop (x21A) and the second primary drop (x21B) to combine the first primary drop with the second primary drop into a combined drop (x22) at a connection point (x32) within a reaction chamber within the printing head so that a chemical reaction is initiated within a controlled environment of the reaction chamber between the first liquid of the first primary drop and the second liquid of the second primary drop; and controlling the flight of the combined drop (x22) at least by means of a stream of gas (x71A, x71B).

An ink-jet recording apparatus includes: an ink-jet head provided with first and second nozzles for jetting a first ink and a second ink respectively, first and second drive elements which apply energy to the first and second inks respectively; a power supply circuit; and a controller. The controller estimates viscosity of the first ink in the first nozzle, controls the power supply circuit to generate a first drive voltage or a second drive voltage higher than the first drive voltage based on the viscosity of the first ink in the first nozzle estimated, drives the first and second drive elements by use of the drive voltage generated in the power supply circuit, and calculates a jetting amount of the first ink to be jetted from the first nozzle and a jetting amount of the second ink to be jetted from the second nozzle.

Provided are an image recording apparatus, a dither mask, and an image recording method capable of reducing occurrence of concentration unevenness without decrease in productivity. In an image recording apparatus that repeats a main scan operation of relatively moving a recording head having a nozzle row with respect to a recording medium in a main scan direction to perform recording and a sub scan operation of relatively moving the recording medium with respect to the recording head in a sub scan direction, a nozzle jetting rate of each nozzle is controlled by a dither mask. The dither mask is subjected to threshold setting so that a sum of a sum of nozzle jetting rates of corresponding nozzles of respective nozzle groups used in recording a first half scan for recording each scan band and a sum of nozzle jetting rates of corresponding nozzles of respective nozzle groups used in recording a second half scan becomes a specific value that is in a defined allowable range, with respect to at least a part of a recording duty range.

A printing system and method for forming an ink droplet through the use of a multi-pulse driving signal.