Provided is a liquid ejecting head that ejects a liquid in a pressure chamber by a piezoelectric device, the piezoelectric device including a vibration plate, a piezoelectric layer containing lead, a first electrode provided between the vibration plate and the piezoelectric layer, and a second electrode provided on a side opposite to a side of the first electrode as viewed from the piezoelectric layer. The piezoelectric layer is preferentially oriented in a (100) plane, a lattice constant c defined by a crystal plane of the piezoelectric layer parallel to a film surface of the piezoelectric layer and a lattice constant a defined by a crystal plane perpendicular to the film surface satisfy 0.9945?c/a?1.012, and the thickness of the piezoelectric device is twice or more the thickness t (t<5 ?m) of the piezoelectric layer.

A liquid circulation device includes a liquid discharge head, a circulation channel through which a liquid is circulated via the liquid discharge head, a first liquid feed pump to supply the liquid to the liquid discharge head in a circulation direction, a second liquid feed pump to collect the liquid from the liquid discharge head in the circulation direction, a filter disposed in the circulation channel upstream from the first liquid feed pump and downstream from the second liquid feed pump in the circulation direction, and a decompression-side reverse channel to bypass the second liquid feed pump. One end of the decompression-side reverse channel is connected to the circulation channel upstream from the second liquid feed pump, and another end of the decompression-side reverse channel is connected to the circulation channel downstream from the filter in the circulation direction.

An overvoltage is prevented from being applied to a circuit. A full-bridge circuit is provided with a first switch having an output terminal connected to one end of a capacitive load, and switching output to the output terminal between a power supply and a ground, a second switch having an output terminal connected to the other end of the capacitive load, and switching output to the output terminal between the power supply and the ground, a first waveform generation section adapted to output a drive waveform for driving the first switch, a second waveform generation section adapted to output a drive waveform for driving the second switch, a detection section adapted to detect voltages of the drive waveforms output by the first waveform generation section and the second waveform generation section, and a control section adapted to control the output of either of the switches based on the voltages detected by the detection section.

A method of ink jet printing, wherein liquid ink is supplied to a plurality of nozzles via a common ink supply passage, and actuators associated with the nozzles are controlled to cause ink droplets to be expelled from the nozzles in accordance with image information to be printed, characterized by the steps of: detecting a situation where a number of the nozzles which are connected to the common ink supply passage and are presently active but stop printing within a given time interval is larger than a given maximum number; if that situation is detected, activating at least one actuator associated with one of the nozzles that stop printing with sub-threshold agitation pulses which cause an agitation of a meniscus in the nozzle without a droplet being expelled.

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.

In accordance with an embodiment, an inkjet head comprises a pressure chamber, an actuator and a control section. The pressure chamber houses ink. The actuator is driven to expand or contract the volume of the pressure chamber in order to eject the ink from an opening of the pressure chamber. The control section applies an expansion pulse of which the width is 0.4 times-0.9 times as large as an AT which is half a natural vibration period during which nozzle negative pressure is changed in the pressure chamber and which expands the pressure chamber to the actuator, and applies a contraction pulse which contracts the pressure chamber to the actuator.

There is provided a liquid discharge apparatus including: a liquid-chamber that communicates with a nozzle and a flow-chapel; a liquid chamber driving unit that changes a volume of the liquid-chamber; and a valve that changes a volume of the flow-channel. At least one of first control of increasing the volume of the liquid-chamber, such that a change amount of the volume of the liquid-chamber is equal to or larger than a volume of the liquid flowing from the flow-channel into the liquid-chamber due to the decrease in volume of the flow-channel by the valve, and second control of decreasing the volume of the liquid-chamber, such that a change amount of the volume of the liquid-chamber is equal to or larger than a volume of the liquid flowing from the liquid-chamber out to the flow-channel due to the increase in volume of the flow-channel by the valve, is executed.

According to one embodiment, an inkjet head includes a pressure chamber connected to a nozzle, an actuator configured to change a pressure in the pressure chamber, and a controller configured to apply an expansion signal to the actuator for expanding the pressure chamber, apply, subsequent to at least one expansion signal, a contraction signal to the actuator for contracting the pressure chamber, and apply, while the pressure chamber is contracted, an intermediate signal for contracting the pressure chamber by less than the contraction signal contracts the pressure chamber.

A jet parameter generation system according to an embodiment of the present disclosure includes a data acquisition section, and a parameter generation section for generating a predetermined jet parameter, using a predetermined analytical method of taking a predetermined input parameter as an explanatory variable and taking a predetermined jet parameter as an objective variable. The parameter generation section determines which one of a first standard for setting a voltage value with which a drop volume of the liquid to be a reference is obtained and a second standard for setting a voltage value with which an ejection speed of the liquid to be a reference is obtained is to be selected, selects a first explanatory variable group when determining to select the first standard, while selecting a second explanatory variable group when determined to select the second standard, and uses the predetermined analytical method using just selected one of the first explanatory variable group and the second explanatory variable group to thereby generate the predetermined jet parameter.

A liquid droplet discharging head includes: a channel member having a channel including a nozzle and a pressure chamber communicating with the nozzle; and a piezoelectric element fixed to the channel member and configured to apply pressure to liquid inside the pressure chamber to discharge liquid droplets of the liquid from the nozzle. A natural frequency Fr of the channel is not less than 250 kHz; and a diameter D [?m] of the nozzle has a relationship of the following expression (1) with the natural frequency Fr [kHz]: 0.0446?Fr+7.5?0.0446?Fr+13.5 . . . (1).