Abstract: A plate shaped slim electrode is mounted on a carriage which supports an ink issuing unit and a charging tunnel, and is driven to travel in the lateral direction. A cylinder shaped rotary deflection electrode is rotatably mounted on the body of an ink jet system printer in a direction parallel to the travelling direction of the carriage. In a preferred form, a slit opening is formed in the center of the plate shaped slim electrode. The plate shaped slim electrode is maintained at the ground potential, whereas the rotary deflection electrode is connected to a high voltage source to establish a high voltage electric field between the plate shaped slim electrode and the rotary deflection electrode.

Abstract: In an ink jet system printer of the charge amplitude controlling type, when it is desired to charge a specific ink drop being formed, the amplitude of charge for the specific ink drops is increased in accordance with a total of field strength of electric fields due to the charge amplitude of the preceding ink drops, the charge of the thus increased amplitude being supplied to the specific ink drop to thereby alleviate any charge distortion.

Abstract: A pair of rotary deflection electrodes are provided to confront with each other in an ink jet system printer in order to deflect charged ink droplets emitted from a nozzle as they pass through a high voltage electric field established therebetween. Cleaners are installed close to the rotary deflection electrodes at the position where the electric field established between the rotary deflection electrodes will not be disturbed by the cleaners in order to sweep the rotary deflection electrodes as they rotate.

Abstract: In an ink jet system printer wherein ink droplets are emitted from a nozzle toward a recording paper, objectionable ink dust is formed and diffused in various directions after the ink droplets impinge upon the recording paper. When the diffused ink dust attaches to a unit such as deflection means, the system may operate erroneously. An electrode is arranged in a position suited for minimizing the deleterious effects of diffused ink dust from the ink jet system printer by the use of an electrostatic attraction force or an electrostatic repulsion force.

Abstract: The size of patterns printed by an ink jet system printer including an ink liquid issuing nozzle, a charging electrode and deflection electrodes is temperature dependent. When the ink liquid temperature increases, viscosity of the ink liquid reduces and hence a flow rate of the ink liquid increases. This causes both mass and a flying rate of an ink droplet emitted from the nozzle to increase. Therefore, a deflection amount becomes smaller and hence the printed pattern size becomes smaller than that of ordinary desired. A temperature senser is provided on an ink conduit adjacent to the nozzle, for detecting the ink liquid temperature and generating detecting signals. A voltage level of video signals applied to the charging electrode or a voltage level applied to the deflection electrodes is varied in accordance with the detecting signals in order to stabilize the size of the printed pattern.