• 반도체디스플레이기술학회지
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• 제4권2호
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• pp.21-24
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• 2005

Ink-jetting characteristics of pulse width and pulse amplitude for a piezoelectric ink jet printer driver have been mapped with various polymer EL ink. In this study, the jetting characteristics have been classified into 4 regime; no Jetting, unstable jetting, stable jetting, and spraying, and the importance of fluid viscosity on the scope of the stable jetting regime has been emphasized. The relation between jetting speed and the width and amplitude of driving signal has also been investigated and the effect of the speed on the jetting characteristics has been discussed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.961-964
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• 2007

본 논문에서는 FEM (Finite Element Method)을 이용한 압전세라믹의 특성해석을 통하여 잉크젯 프린트헤드를 설계, 제작하였다. 압전세라믹의 물질특성과 잉크유체 특성을 고려한 굽힘 모드방식의 구동원리와 이론정립을 하였다. 압전방정식은 압전구조에 의한 공진주파수로 압전 파라미터를 구할 수 있고, 실험을 통하여 이러한 측정값을 얻을 수 있었다. 제작된 압전세라믹 프린트헤드의 잉크드롭 실험결과 통하여 이에 대한 특성을 알 수 있었다. 이때 잉크유체의 음파와 압전 공진주파수 범위 내에서 압전세라믹 응력(변형)의 이득을 발생할 수 있음을 제작한 128노즐의 압전세라믹 잉크젯 프린트헤드로부터 알 수 있었다.

• 대한기계학회논문집A
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• 제31권1호
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• pp.11-17
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• 2007

In this paper, we present a design, analysis, fabrication and performance test of the novel DoD metal-jet system for application to the high-density and high-temperature-melting materials. The theoretical analysis of the metal-jet nozzle system is derived by using electro-mechanical analogy. Based on the theoretical analysis results, we design the metal-jet print head system and fabricate the metal-jet system, which can eject the droplet of lead-free metal solder in high-temperature. In the experimental test, we set up the test apparatus for visualization of the droplet ejection and measure the ejected droplet volume and velocity. As a result, the diameter, volume and the velocity of the ejected droplet are about 65 $\mu$m $\sim$ 70 $\mu$m, 145p1 $\sim$ 180 pl and 4m/s, which shows quite good agreement with the theoretical analysis results of the 75 $\mu$m-diameter and 220 pl-volume of droplet. In comparison with the experimental result, the errors of diameter and volume are 7% $\sim$ 13% and 18 $\sim$ 34%, respectively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1742-1746
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• 2008

An EHD (Electro-Hydro-Dynamic) jet for electrostatic inkjet head shows advantages to print micro-size patterns using various inks because it can generate sub-micron droplets and can use highly viscous inks. Thus, many researchers in industrial fields are concerned about the EHD jet in these days. Since the basic principle of the EHD jet is to form a droplet from an apex of meniscus at the end of the nozzle, the ejection mechanism can be changed by the shape of the meniscus. The stable ejection of the droplet is greatly affected by the shape of the meniscus which is also influenced by surface characteristics of the nozzle, electric potential and ink properties. Experiments have been performed using the nozzles with hydrophilic and hydrophobic coatings in this study. The hydrophobic nozzle forms the stable droplets in wider range of the electric potential than the hydrophilic nozzle does.

• 대한기계학회논문집A
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• 제32권12호
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• pp.1102-1106
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• 2008

Microfluidics deals with the behavior, precise control and manipulation of fluids at a micro scale. It has become increasingly prevalent in various applications such as biomedical applications (diagnostics, therapeutics, and cell/tissue engineering), inkjet head, and fuel cells etc. The issue of inspection and characterization of microfluidics has emerged as a major consideration in design, fabrication, and detection of microfluidic devices. In this paper, we characterize a diffusion based mixing in Y-microchannel using a fluorescent optical scanner based on a DVD pick-up module, which is widely used in optical storages. Using fluorescent dye, we measure the fluorescent intensity that represents the mixing patterns in Y-microchannel. We also compare these experimental results with computational fluid dynamics (CFD) simulation ones. It is shown that the proposed optical scanner can be used as an alternative measurement system with high performance and cost-effectiveness, compared to conventional optical tools such as epifluorescent microscopes using high resolution CCD camera and confocal microscopes with photomultiplier (PMT) detectors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1544-1545
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• 2007

본 논문은 피에조방식으로 구동하는 MEMS 구조의 산업용 잉크젯 헤드를 제작하여 잉크를 충진하여 토출하는 과정에서 토출이 되지 않는 원인 중 하나인 기포에 대해서 연구하였다. 기포를 직접 관찰하기 위한 방법으로 투명한 유리로 Membrane을 제작하여 기포가 발생하여 거동하는 모습을 관찰하였으며 Actuator가 구동하는 헤드내 기포를 구동 중에 관찰하기 위한 방법으로 LDV(Laser Doffler Vibrometer)를 이용하였다. 그 결과, 구동하면서 발생하는 변위의 미세한 차이를 관찰할 수 있었으며 주파수 data의 차이를 관찰함으로써 기포의 크기에 따른 토출의 양태를 구별할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1550-1551
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• 2007

노즐 직경 $30\;{\mu}$인 MEMS 압전 잉크젯 헤드를 이용하여 Ag 나노 잉크를 PDMS 처리된 PI(Polyimide) 기판 위에 토출하였다. 구동주파수 5 KHz에서 액적부피 1.5 pl, 속도가 약 4.5 m/s인 액적이 토출 되었다. 인쇄된 액적의 크기는 직경 약 $12\;{\mu}m$이었다. 메니스커스의 거동에 맞춘 구동파형의 입력에 의해 새틀라이트 없는 매우 작은 액적을 토출할 수 있었다.