Zusammenfassung
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.
Nutzer