| Summary: | 碩士 === 國立臺灣大學 === 機械工程學系 === 85 === The present study aims to investigate the pressure rise in the
ink flow channel and the ink droplet formation process of a
piezoelectric printhead after an electrical pulse is applied to
the printhead. The ink flow channel is simplified as a straight
circular pipe followed by a convergent nozzle. Both numerical
analysis and experimental observations are performed in this
study. In the numerical analysis, a characteristic method is
used to solve the one-dimensional wave equation with nonuniform
cross-section area for obtaining the transient pressure and
velocity variations in the flow channel of the printhead. In
addition, an inexpensive flow visualization system was set up to
observe the ink droplet injection process. After the
piezoelectric material is driven by the input electric pulse,
the ink droplet images can be immediately captured by a charge-
couple device (CCD) camera and stored in a computer through a
frame grabber. The results obtained from the experimental
observations are also compared with the numerical prediction.
The effects of electric pulse shape and voltage for driving the
piezoelectric material on the ink injection length and the
ejected droplet weight are also presented.
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