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.

An inkjet head drive apparatus comprises a pressure chamber, an actuator, a nozzle and a drive signal output section. The pressure chamber accommodates an ink. The actuator increases or decreases volume of the pressure chamber through an applied a voltage. The nozzle is connected with the pressure chamber to eject the ink through the change in the volume of the pressure chamber. When an ejection pulse for the ejection of the ink from the nozzle is repeated for equal to or greater than three times, the drive signal output section outputs a drive signal having a driving waveform including an initial ejection pulse having a first voltage amplitude and the a second ejection pulses and the pulses thereafter having a second voltage amplitude smaller than the first voltage amplitude to the actuator.

In accordance with an embodiment, an inkjet head comprises a pressure chamber configured to house ink; an actuator configured to be arranged corresponding to the pressure chamber; a plate configured to have a nozzle communicating with the pressure chamber; and a driving circuit configured to drive the actuator, wherein the drive circuit applies an auxiliary pulse signal which contains an expansion pulse for expanding the volume of the pressure chamber and a contraction pulse for contracting the volume of the pressure chamber in such a degree as not to eject an ink drop from the nozzle to the actuator before enabling the ink drop to be ejected from the nozzle communicating with the pressure chamber by applying the expansion pulse and the contraction pulse as a drive pulse signals.

A first output section outputs a first parameter calculated for each nozzle in a group obtained by dividing the nozzles into groups for each certain number so that density unevenness of ink ejected from each nozzle in the group is corrected. A second output section outputs a second parameter calculated for each group so that change rate of the density unevenness between groups is corrected. A first register circuit divides first parameters for each nozzle in the group and stores the first parameters. A second register circuit divides second parameters for each group and stores the second parameters. A multiplication section sequentially multiplies the first parameters by the second parameters. A conversion section converts a multiplication value to correction data of each nozzle. A setting section sets the correction data in a memory.

In accordance with an embodiment, an inkjet head comprises a pressure chamber configured to house ink; an actuator configured to be arranged corresponding to the pressure chamber; a plate configured to have a nozzle communicating with the pressure chamber; and a driving circuit configured to drive the actuator, wherein the drive circuit applies an auxiliary pulse signal which contains an expansion pulse for expanding the volume of the pressure chamber and a contraction pulse for contracting the volume of the pressure chamber in such a degree as not to eject an ink drop from the nozzle to the actuator before enabling the ink drop to be ejected from the nozzle communicating with the pressure chamber by applying the expansion pulse and the contraction pulse as a drive pulse signals.

An inkjet head contains a piezoelectric member which alternately includes plural first grooves and plural second grooves respectively constituted by a pair of side surfaces and a bottom surface; a first electrode on at least one of a pair of the side surfaces of each first groove; a second electrode on the side surface to face the first electrode across the piezoelectric member of each second groove; and a driving circuit including plural first drivers for each first electrode and inputting a common first driving waveform to each first electrode, and plural second drivers for each second electrode and inputting a second driving waveform of each second electrode corresponding to print data to each second electrode.

In accordance with an embodiment, an inkjet head comprises a plurality of first driving elements containing a plurality of first pressure chambers respectively communicating with a plurality of first nozzles; a plurality of second driving elements containing a plurality of second pressure chambers respectively communicating with a plurality of second nozzles; a common liquid chamber configured to communicate with a plurality of the first pressure chambers and a plurality of the second pressure chambers; and a controller configured to apply an ejection pulse to the plurality of first driving elements and at least one non-ejection pulse to the plurality of second driving elements before an end time of the ejection pulse.

In accordance with an embodiment, an inkjet head comprises a plurality of first driving elements, a plurality of second driving elements, a common liquid chamber and a controller. A plurality of the first driving elements constitutes a plurality of first pressure chambers respectively communicating with a plurality of first integrated nozzles. A plurality of the second driving elements constitutes a plurality of second pressure chambers respectively communicating with a plurality of second integrated nozzles. The common liquid chamber communicates with a plurality of the first pressure chambers and a plurality of the second pressure chambers. The controller applies an ejection pulse to the first driving element and at least one non-ejection pulse to the second driving element before an end timing of the ejection pulse.

According to an embodiment, an ink jet head includes a discharge unit, a first storing unit, a second storing unit, a waveform generating unit, and a voltage applying unit. The discharge unit discharges ink according to the operation of an actuator. The first storing unit stores a pattern of a voltage to be applied to the actuator. The second storing unit stores a plurality of timer sets. The waveform generating unit generates, on the basis of the timer sets stored by the second storing unit and the voltage pattern stored by the first storing unit, a waveform of the voltage to be applied to the actuator. The voltage applying unit applies the voltage to the actuator on the basis of the waveform generated by the waveform generating unit.

A liquid droplet ejecting device includes a channel member and an actuator. The channel member has a channel. The channel includes a nozzle and a pressure chamber communicating with the nozzle. The actuator is on the channel member and configured to apply a pressure to a liquid in the pressure chamber. A diameter of the nozzle and a natural frequency of the channel are parameters of the liquid droplet ejecting device to satisfy that (1) the actuator has a threshold drive frequency of 100 kHz or more, (2) the nozzle ejects a liquid droplet having a volume of 1.8 pl or more, and (3) the Ohnesorge number is 0.2 or more.