A physical explanation of how air-assist improves the performance of drop-on-demand ink jets: based upon experimental observations

Drop formation characteristics of a jet with and without air-assist are compared. While the normalized drop breakoff process and drop velocity profiles were similar in both cases, the impact of a lower absolute drop velocity and a larger range of time-to media for the jet without air-assist was enough to lower the maximum addressability of the jet. The dynamic range of the jet remained the same despite removal of the air-assist. An ink jet with the dynamic range of 20 kdps can be achieved without the use of air-assist if the system response is designed to permit such a dynamic range. The important element to control is surface wetting.<>