Observation Of Piezoelectric Inkjet Printing For Additive Manufacturing Electronics Based On Machine Vision

Piezoelectric inkjet based additive manufacturing has been widely used in aerospace,flexible electronics and other fields.The principle is that when a periodic waveform voltage is applied to the nozzle piezoelectric ceramic,the compression and contraction of the piezoelectric ceramic will also change with the waveform,and the working liquid in the nozzle will periodically spray the working liquid in a stable state.The ink droplet formation process is affected by many factors such as nozzle and nozzle printing process parameters.The accurate observation of the ink droplet state is the premise of realizing the high-precision production of piezoelectric inkjet.Therefore,this paper takes piezoelectric extrusion nozzle as the research object and machine vision technology as the means to observe the ink droplet generation process,capture ink droplet pictures,study the influencing factors of ink droplet formation,and explore the relationship between the characteristics identification parameters such as the radius and speed of ink droplet and the printing process parameters of the nozzle.The main work is as follows:Firstly,the continuous inkjet and on-demand inkjet printing technologies are analyzed and compared,and the on-demand extrusion piezoelectric nozzle is selected as the research object,and the working principle of piezoelectric inkjet is introduced.Based on the analysis of ink droplet observation method,a set of special equipment for ink droplet observation is designed based on the stroboscopic photography method.According to the application scenario of the equipment,the parts of the equipment are designed,selected,assembled and adjusted.Secondly,the ink droplet image is processed by machine vision technology.Based on the dynamic threshold segmentation method,a segmentation algorithm which can change the threshold value according to the contrast is designed to realize the effective segmentation of the ink droplet feature region.An improved algorithm of the minimum edge droplet radius is designed,and the fitting method of the minimum edge peripheral circle is compared and analyzed.An algorithm for solving ink droplet velocity is designed.Finally,an example is given to verify the effectiveness of the algorithm for solving the droplet radius and velocity.Finally,the printing process parameters of the nozzle are controlled,the ink droplet image is processed,and the characteristic recognition parameters such as the radius and speed of the ink droplet are extracted.The appropriate rising and falling time of the trapezoid wave is found,and the influence of pulse width,voltage amplitude and working frequency on the characteristic recognition parameters of the ink droplet is explored.The feasibility of the observation device and algorithm designed in this paper is verified by experiments.The results of this paper can improve the calculation accuracy of the droplet radius and velocity,improve the quality of inkjet printing,and can be used in the development of new nozzle,inkjet materials and printing technology research,which has important significance.