Aerodynamic effects in industrial Inkjet printing

Abstract

The quality achieved by inkjet printing is limited by various factors, including the nozzle-substrate throw distance, the substrate velocity, and the occurrence of satellite droplets. Under certain conditions, particularly for large throw distances, unacceptable inaccuracies and defects in drop placement occur. In this paper, a new technique based on high-speed imaging and laser optics is presented that allows the visualization of air currents and droplet movement patterns beneath and in the proximity of a printhead and a moving substrate. The images obtained with this technique provide better temporal and spatial resolution than those obtained in previous studies. Tests with two different commercial printheads show that the entrained airflow depends on the interaction with the stream of printed droplets. The formation of unsteady eddies, particularly between nozzle rows, can result in serious errors in drop placement.