Patent ID: 7192121

Claim:
An ink jet printer comprising: a generator of electrical control signals configured to receive a control signal and deliver stimulation signals to a stimulation device; a printing head having a body including at least one printing nozzle; a hydraulic path of the ink including, a stimulation chamber in hydraulic communication with the printing nozzle and configured to emit a pressurized ink jet along an axis of the printing nozzle; the stimulation device mechanically coupled with ink in the stimulation chamber and configured to stimulate the ink jet emitted by the printing nozzle and to break up the ink jet in a controlled way; an ink recovering section configured to recover ink which is not received by a printing substrate; charging electrodes, including upstream electrodes in an upstream area along the axis of the printing nozzle and downstream electrodes in a downstream area along the axis of the printing nozzle, the downstream area being further away from the printing nozzle than the upstream area, upstream and downstream electrodes being connected to different sources of electric potential to maintain in one of the upstream and downstream areas, a first potential equal to a body potential of an ink found in the body of the printing head, and to maintain in the other one of the upstream and downstream areas a second potential different from the body potential of the ink found in the body of the printing head; and deflection electrodes axially located downstream from the charging electrodes, wherein the generator of electrical control signals is further configured to deliver the stimulation signals to intermittently cause controlled breaking up of the ink jet to intermittently form a drop in an upstream breaking position located in the upstream area, thereby separating the ink jet into a drop and a jet section having a length larger than two wavelengths of the ink jet, and configured to cause controlled breaking up of the ink jet or of sections of the ink jet continuously in a downstream breaking position located in the downstream area, the ink jet emitted by the nozzle being thereby transformed after the downstream area into a continuous train of electrically charged and uncharged ink drops.