Droplet generator for a continuous stream ink jet print head

A droplet generator for a continuous stream inkjet print head has an elongate cavity for containing the ink and nozzle orifices in a wall of the cavity for passing the ink from the cavity to form jets. The nozzle orifices extend along the length of the cavity. An actuator is disposed so as to address the face of the cavity opposite the wall to vibrate the ink in the cavity such that each jet breaks up into ink droplets at substantially the same predetermined distance from the wall. The actuator has a plurality of constituent sub-actuators each capable of independent vibration. The combined coverage of the face of the cavity by the sub-actuators is such that the jet break up can be achieved without resonance of the cavity in its dimension from the wall to the face.