A digital printing system includes a print head and a processor. The print head is configured to jet droplets of ink. The a processor is further configured to translate a required shade of a color, to be printed at a given location on a substrate by the print head, into a sequence of pulses, the sequence including: (a) up to a predefined maximum number of driving pulses that cause the print head to jet respective droplets, and (b) a tickling pulse, which has a smaller amplitude than the driving pulses and which causes the print head to jet a droplet smaller than the droplets jetted in response to the driving pulses. The processor is additionally configured to apply the sequence of pulses to the print head.

A liquid ejection head includes a nozzle for ejecting a droplet of a liquid, a pressure chamber connected to the nozzle, an actuator for changing a volume of the chamber according to a voltage signal, and a drive circuit generating the signal for ejecting n droplets, where n is an integer of 3 or more. The signal includes (n−1) ejection pulses, comprising a first pulse lowering the voltage signal to a first value to expand the chamber and then to a second value to contract the chamber, and a second pulse lowering the voltage signal to the first value and then to a third value higher than the second value. The pulses are input at intervals of 0.8λ to 1.2λ, where λ is a primary natural vibration period of the chamber filled with the liquid.

There are provided a liquid jet head and so on capable of ensuring the ejection stability of the liquid even when jetting the liquid high in viscosity irrespective of the structure of the liquid jet head. The liquid jet head according to an embodiment of the present disclosure includes a plurality of nozzles, an actuator having a plurality of pressure chambers, and a drive section for applying a drive signal to the actuator. The plurality of pulses in the drive signal include at least one first pulse configured to expand the volume of the pressure chamber, and at least one second pulse configured to contract the volume of the pressure chamber, and the pressure in the pressure chamber changes with time including a plurality of extremal values in one cycle. First timing as expansion start timing of the volume of the pressure chamber by the first pulse and second timing as contraction start timing of the volume of the pressure chamber by the second pulse are adjacent to each other, and both of the first timing and the second timing are located in a period between two consecutive extremal values of the plurality of extremal values.

Printheads and methods for forming printheads are described herein. In one example, a printhead includes a number of drop generators, wherein a pitch between each adjacent drop generator is substantially the same, and the drop generators alternate between a high drop weight (HDW) drop generator and a low drop weight (LDW) drop generator. The printhead also includes a flow channel from an ink source leading into an ejection chamber associated with each drop generator, wherein the flow channel comprises an inflow region proximate to the ink source, wherein an area of the inflow region is adjusted to control the flux of ink into the ejection chamber.

A correction data setting apparatus, which sets correction data in a memory for storing the correction data for correcting a pulse width of a drive pulse signal applied to each actuator corresponding to each nozzle of an inkjet head, comprises a generation section which sequentially generates a channel No. for individually identifying each nozzle; an output section which outputs a parameter required for arithmetic which represents a characteristic of a correction amount with respect to an arrangement direction of the nozzles; an arithmetic section which executes the arithmetic using the parameter output from the output section to calculate the correction amount for each channel No. generated from the generation section; a conversion section converts the correction amount calculated for each channel No. by the arithmetic section to the correction data; and a setting section sets the correction data obtained for each channel No. by the conversion section in the memory.

There is provided a liquid droplet discharging control device for a liquid droplet discharging apparatus which includes a liquid droplet discharging head in which a plurality of nozzles discharging liquid droplets are formed, discharges liquid droplets while relatively moving the head and a medium in a direction intersecting a direction in which the nozzles are arranged. The liquid droplet discharging control device includes a controller that causes a first nearby nozzle, which discharges a dot adjacent to a dot row corresponding to a predetermined nozzle which is not capable of discharging a liquid droplet, to discharge a liquid droplet for a dot of a large size and that causes a second nearby nozzle, which is separated from the predetermined nozzle and discharges a dot adjacent to a dot row corresponding to the first nearby nozzle, to discharge no liquid droplet for a dot.

The invention relates to a printing method for a digital printing device, comprising a print head having a plurality of printing systems and comprising at least one control apparatus for feeding control signals to the printing systems for the production of ink drops. Each printing system has a nozzle, at least one ink chamber and an activator, e.g. a piezoelectric activator, which is associated with the at least one ink chamber, for the discharge of ink drops from the ink chamber in question via the nozzle in question onto a substrate to be printed on, as a response to a control signal. In the control apparatus, only a single waveform for the control signal having a specified time curve is stored for ink drops of all sizes, comprising, for example, optionally an initial waiting time, a first edge, followed by a first holding time, and, after the first holding time, a second, opposite edge, optionally followed by a second holding time. The size and/or speed of ink drops is varied by virtue of the fact that, at most for a single, intrinsic drop size, the entire stored waveform is transferred as a control signal to the activator in question, while for all other, effective drop sizes, only part of the common, stored waveform is transferred to the activator in question, namely one or more selected portions, while one or more other portions of the stored, common waveform are not supplied to the activator in question in the control signal.

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.

A liquid ejection head includes: a piezoelectric actuator configured to be deformed depending on a driving pulse applied thereto so as to eject liquid filled in a pressure chamber from a nozzle, a ratio of a first local maximum value which is a largest value among a plurality of local maximum values of an ejection speed of the liquid depending on a pulse width and a second local maximum value which is a second largest value thereamong satisfying a predetermined condition; and a control unit configured to successively apply a first driving pulse and a second driving pulse to the piezoelectric actuator.

A digital printing system (10) includes a print head (622) and a processor (20). The print head is configured to jet droplets of ink. The processor is further configured to translate a required shade of a color, to be printed at a given location on a substrate by tire print head, into a sequence of pulses (625, 630), the sequence including: (a) up to a predefined maximum number of driving pulses (625) that cause the print head to jet respective droplets, and (b) a tickling pulse (630), which has a smaller amplitude than the driving pulses and which causes the print head to jet a droplet smaller than the droplets jetted in response to the driving pulses. The processor is additionally configured to apply the sequence of pulses to the print head.