A Multi-Fidelity Model for Simulations and Sensitivity Analysis of Piezoelectric Inkjet Printheads (original) (raw)
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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.
Multi-Disciplinary Simulation of Piezoelectric Driven Microfluidic Inkjet
Volume 6: ASME Power Transmission and Gearing Conference; 3rd International Conference on Micro- and Nanosystems; 11th International Conference on Advanced Vehicle and Tire Technologies, 2009
Modeling, piezoelectric inkjet, multi-physics simulation, reduced-order modeling, piezo actuation, viscoacoustics. free-surface flow, frequency response Piezoelectric inkjet technology is critical to documentation, graphic arts and manufacturing applications. Physical modeling plays an essential role in the development of this technology. In this paper, we present a comprehensive, multi-level, inter-disciplinary simulation approach for piezoelectric inkjet design. This includes a high-fidelity, interdisciplinary detailed simulation method for architecture investigation, and a much faster reduced-order modeling approach that enables interactive design of voltage waveforms. Simulation results are compared with experimental data. The multi-level inter-disciplinary simulation methodology presented here can be applied to designing MEMS and microfluidic devices and systems [1].
The recirculation of ink in an inkjet printhead system keeps the ink temperature and viscosity constant, and leads to the development of a high-performance device. Herein, we propose a recirculating piezo-driven micro-electro-mechanical system (MEMS)-based inkjet printhead that has a pressure chamber, a nozzle, and double restrictors. The design and characteristic analysis are performed using a two-port lumped element model (LEM) to investigate the effect of design parameters on the system responses. Using LEM, the jetting pressure at the pressure chamber, velocity at the nozzle inlet, meniscus pressure, and Helmholtz resonance frequency are predicted and the comparative analysis of the jetting pressure and velocity between LEM and the finite element method (FEM) simulation is conducted to validate our proposed LEM method. Furthermore, the effect of a change in major design parameters on the jetting pressure, velocity, and Helmholtz resonance frequency is analyzed. On the basis of this analysis, the optimized device dimensions are finalized. From our analysis, it is also concluded that the restrictor is more sensitive than the pressure chamber in terms of their variations in depth. As the cross-talk effect can occur due to an array of hundreds or thousands of nozzles, we investigated the effect of a single activated nozzle on the non-activated neighboring nozzles, as well as the effect of multi-activated nozzles on a single central nozzle using our proposed LEM.
International Journal of Mechanical Sciences, 2004
The analysis of oscillatory uid ow in a piezoelectric drop-on-demand cylindrical inkjet print head has traditionally been implemented by computationally expensive numerical methods although the print head itself consists of simple shaped components such as a cylindrical tube surrounded by a piezoelectric actuator, and a conical tube for the nozzle part. In a preliminary design stage, it is strongly desirable to save time and e ort when simulating the impact of the design on the drop generation. For this purpose, approximate analytic solutions, which describe the uid motion in an inkjet print head, are developed. Axial velocity history is fed back to a further drop formation simulation with a simpliÿed 1D FDM model. The strengths and weaknesses of the 1D approach are identiÿed. Despite the compactness of the present approach, the results show encouraging agreement of mass transport rate with experimental data. ?
The Simulation of the Piezoelectric Print Head
Modern Physics Letters B, 2009
This paper investigates the flow dynamic behaviors with respect to different contact angle and frequency of the piezoelectric print head. Its geometric model is divided into three zones for easy description, i.e., channel zone, nozzle zone and ejection observing zone. The length, width and orifice diameter of the micro-channel are 2,000 µm, 400 µm and 30 µm, respectively. The moving wall is located on the top wall of the channel zone in order to obtain proper condition for single drop generation; we applied the numerical simulation by commercial CFD software – CFD-ACE+ 2004. The most important purpose of this study is to find out the optimal frequency to eject droplets periodically and control the volume of droplet ejection which may provide reference for experimental work later on. The results show that by fixing the frequency 20KHz, the nozzle contact angle is from 20 degree to 80 degree, the one droplet interval time value is less than 0.1% and the droplet size value is less than...
The dynamics of the piezo inkjet printhead operation☆
Physics Reports, 2010
The operation of a piezo inkjet printhead involves a chain of processes in many physical domains at different length scales. The final goal is the formation of droplets of all kinds of fluids with any desired volume, velocity, and a reliability as high as possible. The physics behind the chain of processes comprise the two-way coupling from the electrical to the mechanical domain through the piezoelectric actuator, where an electrical signal is transformed into a mechanical deformation of the printhead structure. The next two steps are the coupling to the acoustic domain inside the ink channels, and the coupling to the fluid dynamic domain, i.e. the drop formation process. The dynamics of the printhead structure are coupled via the acoustics to the drop formation process in the nozzle. Furthermore, wetting of the nozzle plate and air bubbles can have a negative influence on the printhead performance. The five topics (actuation, channel acoustics, drop formation, wetting, and air bubbles) are reviewed in this paper. This research connects the product developments for many emerging new industrial applications of the inkjet technology to the fundamental physical phenomena underlying the printhead operation.
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.
Development of an Improved Model for PiezoElectric Driven Ink Jets
Numerical modeling and experimentation are used at Xerox Office Group to design, optimize, and verify the fluid dynamic behavior of phase-change ink jets, including the individual jets in a print head. A typical model of an ink jet is based upon lumped-parameter (no spatial variation) assumptions. While quite accurately predicting the main Helmholz resonant frequency (a key performance measure), a lumped-parameter model does not predict other parasitic frequencies that occur in a typical ink jet. As printer performance improves by increasing the jetting frequency, understanding and controlling these other resonant frequencies becomes critical. This paper documents the improvement of an existing lumped-parameter model by incorporating one-dimensional transmission line elements which substantially increases the ability of the model to predict the frequency response of an ink jet.
Free surface flow and acousto-elastic interaction in piezo inkjet
Modeling plays an essential role in our research on new inkjet technologies. Structural modeling with Ansys includes piezo-electricity. Acoustic modeling in Ansys and Matlab involves fluid-structure interaction. CFD modeling with Flow3D includes wall-flexibility and free surface flow with surface tension. Added to our measurements this reveals the phenomena involved in our main goal: firing droplets of ink at a very high rate with any desired shape, velocity, dimension and a reliability as high as possible.
The Effect of Ink Supply Pressure on Piezoelectric Inkjet
Micromachines
Experimental and numerical analysis of the drop-on-demand inkjet was conducted to determine the jetting characteristics and meniscus motion under the control of the ink supply pressure. A single transparent nozzle inkjet head driven by a piezoelectric actuator was used to eject droplets. To control ink supply pressure, the pressure of the air in the reservoir was regulated by a dual valve pressure controller. The inkjet performance and the motion of the meniscus were evaluated by visualization and numerical simulation. A two-dimensional axisymmetric numerical simulation with the dynamic mesh method was performed to simulate the inkjet dynamics, including the actual deformation of the piezoelectric actuator. Numerical simulation showed good agreement with the experimental results of droplet velocity and volume with an accuracy of 87.1%. Both the experimental and simulation results showed that the drop volume and velocity were linearly proportional to the voltage change. For the speci...