Design and simulation of electrostatic inkjet head

摘要

A laminated, multi-substrate inkjet head that called “electrostatic inkjet head” has been designed, which consists of three parts: upper layer (Si), middle layer (Si), bottom layer (glass). Middle layer includes nozzles, ink cavity and diaphragms. Ink is jetted out of the ink cavity through the nozzle, and diaphragm defined as the bottom of ink cavity. Charging channels is used for supplying ink to the ink cavity. Electrodes on the bottom layer face to the diaphragm, as to drive the diaphragms by electrostatic force. Theoretical analysis and simulation has been done to optimize the design of the ink jet head. Diaphragm with 380µm width, 6000µm length and 5µm thickness is designed in this work, and the gap between the diaphragm and the ground electrode is 1µm. A displacement of 0.26µm can be achieved under 36V DC voltage according to the simulation. Flat-walled diffuser elements were applied as the charging channels that positioned in the upper layer to eliminate the reflux of ink, by which the voltage can be reduced. Simulation of Fluid Structure Interface (FSI) is carried out in ANSYS to analyze the whole process of printing. When the applied voltage is 36V DC, the velocity in the nozzle is 2.82m/s and Weber Number is 8.5. Simulation results show that Weber Number is between 1 and 12, which can provide sufficient power to eject ink drop out of the nozzle. Furthermore, the new design of inkjet head needs lower driving voltage and easier process, which increases the rate of finished products and reduces the cost. Due to these advantages, this inkjet head would have widespread application prospect.