Numerical Modeling of the Motion and Interaction of a Droplet of an Inkjet Printing Process with a Flat Surface (original) (raw)

Analysis of the Droplet Ejection for Piezoelectric-driven Industrial Inkjet Head

2006

A hybrid design tool combining one-dimensional (1D) lumped parameter model and three-dimensional (3D) computational fluid dynamics (CFD) approach has been developed and applied to industrial inkjet head design for the application of direct writing on printed circuit boards (PCB). Lumped element modeling technique is applied to simplify the composite Inkjet print head system and the calculation of lumped parameters such as compliance, resistance and inertance is explained theoretically. Performance of 1D analysis shows that it is useful for the evaluation of a proposed design of inkjet head. Time sequence of droplet generation is verified by the comparison between 3D analysis result and photographic images acquired by stroboscopic technique. The developed model helps to understand the drop formation process and influence of flow part on the jetting performance.

The impact of ink-jet droplets on a paper-like structure

Inkjet technology has been recognized as one of the most successful and promising micro-system technologies. The wide application areas of printer heads and the increasing demand of high quality prints are making ink consumption and print see-through important topics in the inkjet technology. In the present study we investigate numerically the impact of ink droplets onto a porous material that mimics the paper structure. The mathematical framework is based on a free energy formulation, coupling the Cahn-Hilliard and Navier Stokes equations, for the modelling of the two-phase flow. The case studied here consists of a multiphase flow of air-liquid along with the interaction between a solid structure and an interface. In order to characterize the multiphase flow characteristics, we investigate the effects of surface tension and surface wettability on the penetration depth and spreading into the paper-like structure.

Study on droplet formation with surface tension for electrohydrodynamic inkjet nozzle

Journal of Mechanical Science and Technology, 2012

Droplet ejection from an electrohydrodynamic (EHD) inkjet nozzle depends on many factors such as an onset voltage, liquid conductivity, surface tension, etc. Since the surface tension has an influence on the contact angle between the nozzle surface and the liquid droplet, the surface tension change should be investigated for the control of the droplet ejection. In this study, surfactant, which can weaken the surface tension force, was used to analyze the effect of the surface tension. Furthermore, hydrophobic coating of the nozzle surface was considered as another factor for the droplet ejection. Also, a flow visualization technique was developed to observe the droplet formation and ejection from the EHD inkjet nozzle by various surface tension values.

Droplet formation of a thermal sideshooter inkjet printhead

International Journal of Heat and Fluid Flow, 1998

The present study aims to provide numerical predictions on the droplet formation process for a thermal sideshooter inkjet printhead, which directly aects the printing quality of the printhead. The calculation procedure starts from the heat up of the printhead by an input electrical pulse, then obtains the pressure impulse response curve due to the formation and collapse of a bubble in the ink, the ink¯ow motion in the ink nozzle, and ®nally the evolution process of the ejected ink droplet outside the ink nozzle. The governing continuity and momentum equations for the¯ow motion in the ejected ink droplet are solved on the Eulerian frame by an implicit ®nite-dierence scheme. The ink droplet leading is then updated to the new location from the newly obtained velocity. A comparison is made between the present numerical predictions with experimental results. A good agreement has been found. In addition, the present study shows the eects of the operating voltage of electrical pulse, the ink properties, and the gravity on the breako time of ejected droplet from the ink nozzle exit and the separation time of the long tail from main droplet.

Flows on the nozzle plate of an inkjet printhead

Experiments in Fluids, 2007

Flow patterns of ink layers on the nozzle plate of a piezo-driven printhead are investigated. Two different flow types are identified. First, a jet of droplets induces a radial airflow in the direction of the jet, which in turn causes a liquid flow towards the nozzle. Second, the movement of the meniscus in the nozzle causes an equally strong flow, but completely different flow patterns. The results are presented in a phase diagram with pulse amplitude and firing frequency as parameters.

Development of Ink-Particle Flight Simulation for Continuous Inkjet Printer

Volume 7A: Fluids Engineering Systems and Technologies, 2013

An ink-particle flight simulation method for industrial, continuous-type inkjet printers was developed to clarify the factors that influence the print distortion. Print distortion is produced by aerodynamic and electric interference between the ink-particles flying from the nozzle onto the print-target. The necessary functions to do this, such as the calculation of electrostatic force in the electric field between the electrodes, the Coulomb’s force from other charged ink-particles, and the drag force in the inkjet stream for many flying ink-particles were added to a Lagrangian method in the fluid dynamic analysis software that was used for the simulation. The trajectories of the ink-particles flying from this nozzle onto the print target and the air-flow caused by them were calculated simultaneously in the simulation. The simulation results for the velocities and trajectories of the flying ink-particles were compared with the experimental ones using a high-speed camera. These simul...

Pressure response and droplet ejection of a piezoelectric inkjet printhead

International Journal of Mechanical Sciences, 1999

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 modeled 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 to obtain the transient pressure and velocity variations in the flow channel of the printhead. In this analysis, the channel is assumed to have a non-uniform cross section. In addition, a 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 are immediately captured by a charge-couple device (CCD) camera converted to a digital image via a frame grabber, and stored in a computer. The results obtained from the experimental observations are also compared with the numerical prediction. The effects of electric pulse shape and voltage on the ink injection length and the ejected droplet weight are also presented.