Droplet Ejection Behavior in Electrostatic Inkjet Driving

Abstract

The behavior of droplet ejection from needle- and capillary-type electrostatic inkjet nozzles was investigated. The observation of droplet ejection with a high-speed camera revealed that liquid separation due to the stepwise decrease in applied voltage and Taylor cone formation due to the stepwise increase in applied voltage play an important role in ejecting fine droplets. It was also found that the needle-type nozzle could only eject a fine droplet with one pulse in synchrony with the switching on and off of a rectangular-wave voltage, while the capillary-type nozzle could not always eject a droplet with one pulse at all frequencies. Printing characteristics of the needle-type nozzle were also compared with those of the capillary-type nozzle.