Ink drop motion in wide-format printers I. Drop flow from Drop-On-Demand (DOD) printing heads

The flow of ink drops was investigated for use in wide-format printing devices. The behavior of ink drops ejected from Drop-On-Demand (DOD) piezoelectric (push-mode) printing heads was defined and measured using optical techniques. The combination of velocity measurements from the Laser Doppler Velocimeter and data captured in images taken by an Image Visualization system gave a comprehensive view of the printing head performance. The piezoelectric printing head was examined close to real operational conditions in order to determine the optimal parameters for quality printing. The results show that printing inaccuracy is mainly caused by the appearance of satellite drops. Some recommendations are given for improving the operation of two printing heads examined. A computer simulation of a piezoelectric push-mode Drop-On-Demand ink jet printing head was also presented. The simulation dealt with the pressure pulse causing the ejection of a single drop and its flight towards the printing medium. The Simulated results showed good agreement with the experimental results, and a connection between the voltage pulses that were applied to the piezoelectric crystal and the resulting pressure was established. (C) 2008 Elsevier B.V. All rights reserved.