Patent ID: 8191997

Claim:
A liquid droplet jetting apparatus which jets a droplet of a liquid onto a medium, comprising: a liquid droplet jetting head which jets the droplet, including: a cavity unit in which a plurality of pressure chamber rows each having a plurality of pressure chambers aligned in a row direction is formed; and a piezoelectric actuator which causes selectively the liquid in each of the pressure chambers to be jetted, and includes a plurality of piezoelectric material layers stacked covering the pressure chambers; a plurality of individual electrodes arranged on a first surface of the piezoelectric material layers, at positions corresponding to the pressure chambers, respectively; a first common constant electric potential electrode which is formed on a second surface of the piezoelectric material layers, which overlaps with a portion of each of the individual electrodes, and which forms a plurality of second active portions in areas of the piezoelectric material layers each sandwiched between one of the individual electrodes and the first common constant electric potential electrode; and a second common constant electric potential electrode which is formed on a third surface of the piezoelectric material layers, which has a form of a mesh overlapping with a central portion of each of the individual electrodes, and which forms a plurality of first active portions in an area, of the piezoelectric material layers, each sandwiched between one of the individual electrodes and the second common constant electric potential electrode; and a voltage applying mechanism which applies a voltage to the piezoelectric actuator, wherein when a voltage is applied to the first active portions and the second active portions by the voltage applying mechanism, the first active portions and the second active portions both elongate in a first direction toward the pressure chambers, and contract in a second direction which is orthogonal to the first direction, respectively, and when the voltage applying mechanism applies the voltage to the first active portions, the voltage applying mechanism does not apply the voltage to the second active portions, and when the voltage applying mechanism does not apply the voltage to the first active portions, the voltage applying mechanism applies the voltage to the second active portions.