Abstract: In an ink jet system printer of the charge amplitude controlling type which records character patterns in, for example, a 5 .times. 7 dot matrix pattern, ink droplets not assigned to primary matrix dots are used for interpolation dots which will be deposited between two adjacent primary matrix dots on a record receiving member. The printing quality can be enhanced by provision of these interpolation dots.

Abstract: In ink jet system printers of charge amplitude controlling types ink drops issuing from a nozzle and rapidly traveling in their path toward a record receiving member are subjected to air resistances. Particularly the individual charged ink drops serving for printing purposes are under influences of air resistances which are different in accordance with the presence and absence of preceding charged ink drops and such differences result in faulty printing.In order to minimize the occurrence of distortions in the recording as described above the control system disclosed herein produces correction signals in accordance with the conditions of presence charged and absence of the preceding ink drops to adjust the amplitude of charges on the individual ink drops, thereby obviating the distortions in the recording due to the air resistances.

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.