Piezoelectric ink jet formation

There are two types of impulse printers (Eig. 19). A piezoelectric ink jet propels a drop by flexing one or more walls of the firing chamber to decrease rapidly the volume of the firing chamber. This causes a pressure pulse and forces out a drop of ink. The flexing wall is either a piezoelectric crystal or a diaphragm driven by a piezoelectric incorporated into the firing chamber (Eig. 19a). Thermal impulse ink jets also propel one drop at a time, but these use rapid bubble formation to force part of the ink in a firing chamber out the orifice (Eig. 19b). 

Fig. 19. Ink-jet system (a) piezoelectric ink-jet firing chamber and (b) bubble formation ia thermal ink-jet technology.

It is considered that the drop formation in the ink jet printing process is e governed by the timing of the electric pulse. This piezoelectrically controls the ink flow, inertia forces, viscous forces, surface tension and gravity. The final process model consists of two, one-dimensional equations originating from the kinematic boundary condition, the normal and tangential components of the traction boundary condition and the z-component of the momentum equation, thus ... 

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