Improvement of Firing Frequency Limits by Investigation of Ejection Failure Modes in Thermal Inkjet Print Heads

Ejection failure modes determining the firing frequency limit in thermal inkjet heads were investigated from performance experiments and numerical simulations. Dominant failure modes were affected by the flow resistance ratio in the ink flow passages. Optimal flow resistance ratios were obtained experimentally to provide maximum frequency limits for both mono and color inkjet heads. Numerical simulations were performed on the meniscus oscillation, the ejection behavior in consecutive firing, and the cross-talk induced flow. Numerical results supported the importance of flow resistance ratio in maximizing firing frequency limit in both unit nozzle and multi-nozzle firing. Our investigation will help to develop the inkjet print heads of more reliable high-speed performance.