Patent ID: 7780274

Claim:
A droplet ejection device comprising: a cavity unit having a plurality of nozzles and a plurality of pressure chambers which are held in communication with the respective nozzles; an actuator unit including a plurality of actuators corresponding to the respective pressure chambers, such that each of said actuators is operable to change a volume of a corresponding one of said pressure chambers whereby a droplet is ejected from said corresponding one of said pressure chambers through a corresponding one of said nozzles; and a controller operable to control ejection of the droplet from each of said pressure chambers, wherein said plurality of actuators include at least four electrodes and a piezoelectric body, wherein said at least four electrodes are provided by a plurality of electrode layers each including at least two of said at least four electrodes, said at least two of said at least four electrodes being electrically independent from each other, wherein said piezoelectric body is provided by at least one piezoelectric layer interposed between said plurality of electrode layers, wherein said pressure chambers are sorted into groups in at least two different manners, such that each of said pressure chambers belongs to at least two groups which are formed by sorting in the respective different manners, wherein each of said at least four electrodes is arranged to correspond to at least two of said pressure chambers belonging to one of said groups which is formed by sorting in a corresponding one of said at least two different manners, so that each one of said pressure chambers corresponds to at least two corresponding ones of said at least four electrodes, and wherein said controller controls an electric voltage that is to be applied to each of said at least two corresponding ones of said at least four electrodes, for controlling ejection of the droplet from said each one of said pressure chambers.