An inkjet head includes a pressure chamber storing ink, a nozzle communicating with the chamber, an actuator ejecting the ink through the nozzle by changing a volume of the chamber, and a circuit outputting a drive signal to the actuator with a drive waveform having a cycle based on a number of gradation levels being used for printing. When printing is performed using three or more gradation levels, the circuit outputs the signal that has a multi-drop drive waveform including two or more first waveforms for ejecting first to (n−1)-th droplets of the ink where n is equal to or greater than 3, a second waveform for ejecting an n-th droplet of the ink, and an intermediate time between the first waveform for ejecting the (n−1)-th droplet and the second waveform for ejecting the n-th droplet. The intermediate time is longer than a time between two adjacent first waveforms.

A recording apparatus includes a liquid ejection head, where the liquid ejection head includes: an ejection port, a first substrate, and a temperature detection element. The ejection port ejects liquid and includes a protrusion extending toward an ejection port inside. The first substrate includes a heating element that ejects liquid from the ejection port using heat. The temperature detection element detects temperature of the first substrate. Driving of the heating element is controlled based on whether a difference between a voltage value Vp1 measured by the temperature detection element and a preset voltage value Vp01 has a positive value within or outside a predetermined range or a negative value outside the predetermined range. The voltage value Vp1 is measured when a temperature change amount becomes maximum in a temperature falling process of a second substrate located, after the heating element is driven, at a position corresponding to the heating element.

An inkjet printing method may includes a dot pattern printing process of printing a dot pattern group by discharging ink at a preset position of a surface of an object using a nozzle group for forming a dot pattern so that dropped droplets are not in overlap with each other, a connection pattern printing process of printing a connection pattern group by discharging ink at a position between neighboring patterns using a nozzle group for forming a connection pattern so that the same attractive force acts to the neighboring patterns dropped on the surface of the object, and a finishing printing process of finishing a coating of the surface of the object by discharging ink to an area except for neighboring dropped droplets using a nozzle group for finishing so that the same attractive force act to the dropped droplets that are dropped on the surface of the object.

A method, computer program product and system for precision inkjet printing. A control variable vector of actuation parameters associated with an inkjet waveform is determined. A printhead is then actuated to eject a grid of droplets from an inkjet onto a substrate based on the inkjet waveform. An image of the grid of droplets on the substrate is acquired. The acquired image is then processed to calculate a fitness function of the inkjet waveform that includes a function of sensed output variables associated with printing characteristics. The control variable vector is then adjusted by updating its topology based on the fitness function to obtain an optimized control variable vector associated with an optimized inkjet waveform.

A liquid discharge apparatus includes: a liquid discharge head configured to discharge a liquid from a nozzle; a drive waveform generator configured to generate a drive waveform including multiple drive pulses to be applied to the liquid discharge head, the multiple drive pulses successively including: a first drive pulse configured to cause the liquid discharge head to discharge the liquid; a second drive pulse configured to cause the liquid discharge head not to discharged the liquid while causing meniscus of the liquid in the nozzle in the liquid discharge head to vibrate; and a third drive pulse configured to cause the liquid discharge head to discharge the liquid; in time series.

A liquid discharge method of discharging a liquid from a nozzle of a liquid discharge head by applying a drive pulse to a drive element of the liquid discharge head includes an acquisition step of acquiring a state of a dot formed on a recording medium by the liquid discharged from the nozzle, as a recording condition, and a driving step of applying the drive pulse that varies depending on the recording condition acquired in the acquisition step, to the drive element. The drive pulse may include a first potential, a second potential different from the first potential, and a third potential different from the first potential and the second potential. The second potential may be to be applied after the first potential, and the third potential may be to be applied after the second potential.

According to one embodiment, an inkjet head includes a pressure chamber for ink, a nozzle plate including a nozzle connected to the pressure chamber, an actuator to change a volume of the pressure chamber, and a drive circuit that drives the actuator. The drive circuit drives the actuator according to a drive waveform including an expansion waveform, a first weak contraction waveform, a contraction waveform, and a second weak contraction waveform.

The present invention discharges ink from a plurality of inkjet heads and is used when performing drive whereby one droplet or a plurality of droplets are discharged onto and united on one pixel. A drive signal includes a drive waveform comprising N number (N being an integer of at least 2) of drive waveform elements and is configured so as to fulfil the relationship 1.1 Tc≤Ts≤1.4 Tc, when Tc is the natural vibration cycle determined from the inkjet head structure and Ts is the time from the start point of the drive waveform to the start point of the subsequent drive waveform. As a result, velocity deviation caused by the resonant frequency of a piezoelectric actuator driving the inkjet head can be suppressed when driving an inkjet head using multiple gradations.

A grayscale inkjet printing method including the steps of: a) supplying a pigmented inkjet ink to a grayscale print head having nozzles with an outer nozzle surface area smaller than 500 μm.sup.2 and having an acoustic resonance period ARP of not more than 5.5 μs; and b) applying a voltage wave form for ejecting pigmented inkjet ink from a nozzle of the grayscale print head within one jetting cycle; wherein the pigmented inkjet ink has a viscosity of at least 3.8 mPa.Math.s at jetting temperature and a shear rate of 1,000 s.sup.−1; wherein the voltage wave form for ejecting the largest ink droplet includes, in chronological order, a first ejecting pulse having an amplitude A1 and a second ejecting pulse having an amplitude A3 with the amplitude A1 complying with the relationship: 0.50×A3<A1<1.40×A3; and wherein a time period between the end time of the first ejecting pulse and the end time of the second ejecting pulse defines an idle time period including no other ejecting pulse, the time period having a duration between 1.5 to 2.5 times the acoustic resonance period ARP; and wherein any non-ejecting pulse having an amplitude A2 present during the idle time period complies with the relationship: A2≤0.15×A3. An inkjet printing system is also disclosed.

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.