Aero-dynamical motion of charged droplets ejected from the 26 μm nozzle [continuous jet printing]

Although bubble jet and some other on-demand type ink jet printers have become popular, the continuous jet printing system has more wide applicability in droplet handling systems. The authors have investigated this type of ink jet system with a 39 μm nozzle. Since smaller droplets are preferable for color and/or gradation printing, they stepped into the use of 26 μm nozzles. The experimental system is basically the same as the 39 μm system and the aerodynamical behaviour of droplets was examined by changing various parameters such as frequency, pressure, vibration voltage to nozzle and charging voltage. As the tip of jet should stay within the region of the charging electrode and the droplet train has to be stable, a vibrating frequency of 80 kHz and a voltage of 20 Vp-p were chosen, The pressure applied to the reservoir was 300 kPa or 350 kPa. Experimental results revealed that the aerodynamic effect on droplets is much stronger than those of the 39 μm nozzle