• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1219-1225
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• 2003

According to the increase of lifetime and efficiency, the interest in the pLED has dramatically increased recently because pLED can be applied to large-size and flexible displays. The core process in the manufacture of pLED is the printing process of red, green and blue light emitting polymers (LEP), and inkjet printing method is one of the promising technology to print red, green and blue LEP on glass substrates. In this work, we developed a multi-head inkjet patterning system with 3 heads for each color. The developed inkjet patterning system is composed of the precise positioning system, head controller circuit, real-time ink drop evaluation system, maintenance system, and stable ink supply system. Finally, we investigated the stability and reliability of the system by printing red, green and blue LEP on the dummy substrate.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.128-133
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• 2007

An electrostatic inkjet head can be used for manufacturing processes of large display systems and printed circuit boards (PCB) as well as inkjet printers because an electrostatic field provides an external force which can be manipulated to control sizes of droplets. The existing printing methods such as thermal bubble and piezo inkjet heads have shown difficulties to control the ejection of the droplets for printing applications. Thus, the new inkjet head has been proposed using the electrostatic force. A numerical analysis has been performed to calculate the intensity of the electrostatic field using the Maxwell's equation. Also, experiments have been carried out to investigate the droplet movement using a downward capillary with outside diameter of $500{\mu}m$. Gravity, surface tension, and electrostatic force have been analyzed with high voltages for a drop-on-demand ejection. It has been observed that the droplet size decreases and the frequency of the droplet formation and the velocity of the droplet ejection increase with increasing the intensity of the electrostatic field using high-speed camera.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.20.2-20.2
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• 2010

Recently inkjet printing technology has been developed in the areas of low cost fabrication in environmentally friendly manufacturing processes. Although inkjet printing requires the interdisciplinary researches including development of materials, manufacturing processes and printing equipment and peripherals, manufacturing a printhead is still core of inkjet technology. In this study, a piezoelectric driven DOD (drop on demand) inkjet printhead has been fabricated on three layers of the silicon wafer in MEMS Technology because of its chemical resistance to industrial inks, strong mechanical properties and dimensional accuracy to meet the drop volume uniformity in printed electronics and display industries. The flow passage, filter and nozzles are precisely etched on the layers of the silicon wafers and assembled through silicon fusion bonding without additional adhesives. The piezoelectric is screen-printed on the top the pressure chamber and the nozzle plate surface is treated with non-wetting coating for jetting fluids. Printheads with nozzle number of 16 to 256 have been developed to get the drop volume range from 5 pL to 80 pL in various industrial applications. Currently our printheads are successfully utilized to fabricating color-filters and PI alignment layers in LCD Flat Panel Display and legend marking for PCB in Samsung Electronics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.655-658
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• 1997

In this paper, we intend to develop optimized design algorithm by deciding design parameters which are considered in the first design stage of inkjet printer head. thus, the parameters are such as electric pulse, input voltage of actuator to operate actuator, shape dimension of actuator an so on. in the first design stage, according to such parameters, a lot of time and money to develop inkject printer head are needed. to reduce trial and error and to save development time in the first design stage, optimized design algorithm is required all the more. design algorithm was developed via commercial FE analysis code(ANSYS & COENTOR) for the readability and convenience of algorithm. the reasonability of algorithm was verified by implementing analysis of system stage based on the data of piezoelectric actuator which was designed through algorithm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.2 s.257
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• pp.141-150
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• 2007

This paper presents a lumped model to predict crosstalk characteristics of thermally driven inkjet print heads. Using the lumped R-C model, heating characteristics of the head are predicted to be in agreement with IR temperature measurements. The inter-channel crosstalk is simulated using the lumped R-L network. The values of viscous flow resistance, R and flow inertance, L of connecting channels are adjusted to accord with the 3-D numerical simulation results of three adjacent jets. The crosstalk behaviors of a back shooter head as well as a top shooter head have been investigated. Predictions of the proposed lumped model on the meniscus oscillations are consistent with numerical simulation results. Comparison of the lumped model with experimental results identifies that abnormal two-drop ejection phenomena are related to the increased meniscus oscillations because of the more severe crosstalk effects at higher printing speeds. The degree of crosstalk has been quantified using cross-correlations between neighboring channels and a critical channel dimension for acceptable crosstalk has been proposed and validated with the numerical simulations. Our model can be used as a design tool for a better design of thermal inkjet print heads to minimize crosstalk effects.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.337-342
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• 2022

Although printing technology has recently been widely used in IT fields including displays and fuel cells, residual and thermal stress are generated by a manufacturing process of stacking the layers of the print head and result in the substrate deformation and nozzle plate crack, which may cause ink leaks or not be ejected onto a desired region. Therefore, in this paper, we propose a new design of thermal inkjet print head with a robust and reliable structure. Diverse types of inkjet print head such as a rib, pillar, support wall and individual feed hole are designed to reduce the deformation of the substrate and nozzle plate, and their feasibility is numerically investigated through FEA analysis. The numerical results show that the maximum stress and deformation of proposed print head dramatically drops to at least 40~50%, and it is confirmed that there is no nozzle plate cracks and ink leakage through the fabrication of pillar and support wall typed print head. Therefore, it is expected that the proposed head shape can be applied not only to ink ejection in the normal direction, but also to large-area printing technology.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.689-690
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• 2009

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.8
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• pp.417-422
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• 2006

This paper presents the effect of driving waveform for piezoelectric bend mode inkjet printhead with optimized mechanical design. Experimental and theoretical studies on the applied driving waveform versus jetting characteristics were performed. The inkjet head has been designed to maximize the droplet velocity, minimize voltage response of the actuator and optimize the firing frequency to eject ink droplet. The head design was carried out by using mechanical simulation. The printhead has been fabricated with Si(100) and SOI wafers by MEMS process and silicon direct bonding method. To investigate how performance of the piezoelectric ceramic actuator influences on droplet diameter and droplet velocity, the method of stroboscopy was used. Also we observed the movement characteristics of PZT actuator with LDV(Laser Doppler Vibrometer) system, oscilloscope and dynamic signal analyzer. Missing nozzles caused by bubbles in chamber were monitored by their resonance frequency. Using the water based ink of viscosity of 4.8 cps and surface tension of 0.025 N/m, it is possible to eject stable droplets up to 20 kHz, 4.4 m/s and above 8 pl at the different applied driving waveforms.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.505-508
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• 2006

An electrostatic ink jet head can be used for manufacturing processes of large display systems and printed circuit boards (PCB) as well as inkjet printers because an electrostatic field provides an external force which can be manipulated to control sizes of droplets. The existing printing methods such as thermal bubble and piezo inkjet heads have shown difficulties to control the ejection of the droplets for printing applications. Thus, the new inkjet head using the electrostatic force has been proposed in this study. In order to prove the theory of the developed electrostatic ink jet head, the applicable and basic theory has been studied using distilled water and water with sodium dodecyl surfate (SDS). Also, a numerical analysis has been performed to calculate the intensity of the electrostatic field using the Maxwell's equation. Furthermore, experiments have been carried out using a downward glass capillary with outside diameter of $500{\mu}m$. The gravity, surface tension, and electrostatic force have been analyzed with high voltages of 0 to 5kV. It has been observed that the droplet size decreases and the frequency of the droplet formation and the velocity of the droplet ejection increase with increasing the intensity of the electrostatic field. The results of the experiments have shown good agreement with those of numerical analysis.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1476-1478
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• 2009

The characteristics of polymer inkjet printing were investigated systematically in this paper. PEDOT/PSS as a hole injection layer and MEH-PPV as a light emitting layer were used for inkjet printing experiment. Inkjet head controlling technology and surface modification technology were also applied for polymer inkjet printing. With the developed polymer inkjet printing technology, OLED(Organic Light Emitting Display) was successfully fabricated and demonstrated.