Study On The Dynamic Characteristics Of Piezoelectric Inkjet Print Head

Inkjet printing is a non-contact printing technology,which has great advantages in many fields because of its low cost,high durability,miniaturization and high controllability.As one of its important branches,piezoelectric inkjet printing technology is widely used in electronics manufacturing,life sciences and rapid prototyping technology for its advantages of miniaturization,mass production,long life and low requirements of ink.Dynamic testing plays an important role in the performance,structure and manufacturing of MEMS devices.In this paper,the numerical simulation and laser Doppler test system are used to study the dynamic characteristics of curved piezoelectric inkjet print head,which is important for the formation of droplets.The following is the main contents of this paper:(1)The overall structure design of the curved piezoelectric inkjet print head was introduced.The characteristics of piezoelectric film,vibrating film,metal electrode and chamber material were also described in detail.The formation mechanism of droplets was explained in combination with piezoelectric vibration and piezoelectric injection theory,which provided the theoretical basis for subsequent dynamic simulation.(2)The dynamics simulation of the piezoelectric actuator and the print head was carried out.Firstly,the structural parameters such as length,width and thickness were determined based on the resonant frequency and the displacement.Secondly,According to the modal analysis results of the piezoelectric actuator,the vibration mode most suitable for droplet ejection was obtained,and the driving frequency range was determined.finally,the influence of the fluid-solid coupling on the dynamic characteristics was compared.(3)The two-phase flow model of piezoelectric inkjet was established.According to the simulation results,the optimal values of physical properties such as viscosity and surface tension of the ink were determined.The effects of three shapes of nozzles on the jetting effect were compared,and the nozzles which were most favorable for droplet formation were selected.and the size of the nozzle radius and thickness were optimized.The influence of the surface state of the inner wall and the outer wall of the nozzle on the shape of the droplet was analyzed,and the surface treatment process of the nozzle of the print head was finally determined.(4)The laser Doppler vibration measurement system and the basic excitation method were introduced.The actual vibration direction,vibration mode were measured.A method for measuring the resonant frequency by laser Doppler vibrometer and basic excitation methodwas proposed.The piezoelectric actuator and the print head were excited by fast sine sweep and white noise,The speed response was measured and the power spectrum was obtained by combining MATLAB software to determine the first-order resonant frequency under different conditions.