Effect of Pressure Variation on Inkjet-Printed Line Pattern with Various Step Sizes of Ejected Droplets

J-K Wang, W-S Hwang, M-H Tsai, Y-F Liu
National Cheng-Kung University, TW

Keywords: micro droplet, inkjet printing, array, line


This study investigates the effect of droplet deposition dynamics on inkjet-printed line features of deionized water using numerical analysis. Simulation results show that kinetic energy dissipation during the droplet deposition process transforms into inner wave propagation within the ink fluid on a substrate. In addition, it induced the impaction pressure variation for single droplet behavior having diameter of 40 μm with the impact velocity of 2 m/s. During deposition, the pressure variation at the bottom of a droplet is related to the deposition evolution and dot morphology. At the initial contact with the substrate (between 1 and 4 μs), the pressure of the droplet increased from -31.698 to 11.573 kPa. The droplet then extended to its maximum area and became concave at its center at 15 μs. At 22 μs, the extended droplet started to rebound. After 43 μs, the residue energy caused slight pressure vibration until the static state was reached. The equilibrium pressure within the droplet was 2.050 kPa. The simulation results are consistent with experimental observations in terms of droplet extension, rebound, and equilibrium. Moreover, the effects of pressure propagation during the evolution of droplet deposition on the line printing process are presented.