Article,
A Study on Drying Process of Ink at the Inkjet Nozzle Using a Laser Doppler Vibrometer
NIP &\#38; Digital Fabrication Conference, (2011)
Abstract
In drop-on-demand inkjet systems, the nozzle clogging due to evaporation is our great concern. We have developed a novel method for measuring the change of ink viscosity at the nozzle. To estimate the ink viscosity, meniscus vibration states are measured by a laser Doppler vibrometer and the results are verified by numerical simulation results using an equivalent circuit model of inkjet head.
Using our method, the change of the ink viscosity have been measured with changing idle time (non-jetting time). The results show the ink viscosity at the nozzle increases by two steps via a quasi-equilibrium state, and they are qualitatively consistent with a theoretical prediction. We have also measured the change of the ink viscosity with jetting actions after some idle time. The results indicate the existence of two step recovery process about the ink viscosity. In short term, ink viscosity recovers by refreshing the ink at the nozzle. In long term, that recovers by refreshing the ink in the pressure chamber. As a result, it was found that ink viscosity at the nozzle and that in the pressure chamber can be separately estimated by measuring the recovery process using our method.
