Application Of The Droplet Formation And Characteristic Based On Piezoelectric Inkjet Printing

Along with the developing of digital printing technology, the piezoelectric ink-jet printing technology, as an economical, durable and high efficiency ink-jet technology, has been widely applied. The ink-jet droplet as the fundamental element of image reproduction, undertakes the basic function of image constituting, tone reproduction and color reproduction, it’s one of the key points in printing reproduction. Many characteristics of ink-jet droplet affect printing reproduction quality, as for the generation of droplet, the flying orbit of the droplet in the medium, the transformation of the droplet during the flying process, the drying process of the droplet on the substrate and the configuration of the droplet on the substrate. As one of the primary digital printing technology, the piezoelectric ink-jet printing parameters will be the key points of research work on this area, for example, the droplet size and its stabilization, the generation of droplet tail and satellite droplet, the instantaneous flying velocity of droplet at the side of the nozzle, the dynamic surface tension of the droplet during the flying process. In one word, the aim of the researching work on piezoelectric ink-jet printing technology is achieving the standardization, controllable and high speed. This paper researching on the piezoelectric ink-jet printing process by modeling, software analog and experiment testing, and all these works are based on the jetting theory. From the process, an effective analog model for piezoelectric ink-jet printing has been found. Based on this model, many droplet characteristics has been researched, include the droplet geometry on substrate, the droplet flying orbit during jetting process, ink droplet drying and the dynamic surface tension of droplet. After all, the primary researching work and conclusion as follow:(1) Theoretic modeling of piezoelectric ink-jet printing process and definite its boundary condition, after that, solving the equation at the boundary condition. Analog the printing process under the right boundary condition by software, and the analog result equal to the solution of the equation. At last verifying the analog result by experiment.(2)In this thesis, we modeling the piezoelectric ink-jet printing process, analyzed the effectiveness of surface tension, viscosity and ink pressure to the geometry of the droplet, researching on the relationship on the surface tension and droplet formation, especially the surface tension and the droplet formation process.(3) The flying orbit of droplet has been researched by modeling and experiment, and after that, the vertical and horizontal flying orbit has been analyzed respectively. At last this method has been confirmed by experiment.(4) As web-feed ink-jet printing press be concerned, this paper researching on the position characteristics of ink droplet on moving substrate, so that we can make sure the printing quality under this printing condition.(5) Ink drying process has been analyzed, and based on the drying theory, the ink drying mathematical model has been found based on the drying temperature and air speed. This is the theory foundation of the ink drying for high speed ink-jet printing, meanwhile a high efficiency ink drying set has been developed.(6) Announced a surface tension calculation method based on the contour fitting, this method is effective to calculate the dynamic surface tension of the flying ink droplet.At last, conclude the researching work and record for this thesis, analyzed the defects of the researching process, meanwhile giving some advises for the future researching work in this area.