Patent ID: 7520580

Claim:
An ink droplet ejection device comprising: a plurality of nozzles; a plurality of pressure chambers held in communication with the respective nozzles; a plurality of actuators each operable to apply an ejection pressure to an ink stored in a corresponding one of said pressure chambers, for causing an ink ejection from said corresponding one of said pressure chambers through one of said nozzles that is held in communication with said corresponding pressure chamber, whereby an image formed as a result of the ink ejection is produced on a medium; and a controller operable to supply a control signal to each of said plurality of actuators, and incorporating a drive pulse train into said control signal for causing ejection of at least two cooperative ink droplets that cooperate with each other to form one dot of the image produced on the medium, wherein said drive pulse train includes at least two drive pulses, one of said at least two drive pulses having a first pulse width smaller than a maximizing value which is dependent on a length of a propagation time required for a pressure wave to be propagated to each of said nozzles via a corresponding one of said pressure chambers and which maximizes an ejection velocity and a volume of each ink droplet to be ejected, another one of said at least two drive pulses having a second pulse width larger than said maximizing value.