• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.79-80
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• 2010

• Proceedings of the KIEE Conference
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• 2007.07a
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.125-126
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• 2009

• 프린팅코리아
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• v.12 no.8
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• pp.98-99
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• 2013

오늘날 인쇄 미디어는 디지털과 온라인 미디어 플랫폼의 확장으로 지속적인 압박을 받고 있다. 인쇄사들은 인쇄부수와 인쇄 광고 수익의 지속적인 감소로 어려움을 겪고 있다. 이에 시문 구독자와 광고주 모두에게 매력적인 동시에, 신문사의 건전한 이익을 위한 새로운 신문 비즈니스 모델이 절실히 요구되고 있다. 코닥은 그에 대한 해답이 '코닥 프로스퍼 S시리즈 초고속 디지털 잉크젯 헤드'에 있다고 말한다.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.73-79
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• 2011

Inkjet printhead may have a lot of nozzles to increase productivity as a manufacturing tool. So, the uniformity of jetting performance among a lot of nozzles has been one of the key issues in inkjet technology In this study, we investigated the cross-talk effect which should be reduced for uniform jetting performance among a lot of nozzles. Due to the cross-talk, the jetting performance of a nozzle can be affected when neighboring nozzles are firing. For experimental study, we used commercial inkjet head SE-128 from Dimatix. To understand the cross-talk effect of SE-128 head, we measured the change in jetting speed of a nozzle when neighboring nozzles are jetting. The measured jetting speed was compared to the case of one nozzle jetting. Also, we used laser vibrometer to measure change in pressure wave due to cross-talk. As a result of the cross-talk, the jetting speed can become faster or sometimes slower depending on firing nozzle location. If the all nozzle are jetting, the jetting speed of a nozzle became slower because the pressure wave for jetting is reduced.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.4
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• pp.455-460
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• 2012

The Electrostatic Inkjet system has many applications in cost and time effective manufacturing of printed electronics like RFIDs, OLEDs and flexible displays etc. This paper presents pneumatic ink supply system for an electrohydrodynamic deposition (EHD) setup for the precise pressure control to produce a small amount of discharge at the end of the capillary. The meniscus shape depends upon the applied pneumatic pressure to the ink supply system. Furthermore, this paper also compares meniscus shapes at different applied pneumatic pressures. It is concluded that patterning of constant line-width can be achieved better by controlling the meniscus shape using this technique.

• 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.

• Proceedings of the KIEE Conference
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• 2007.07a
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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.

• Journal of Institute of Convergence Technology
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• v.1 no.1
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• pp.34-40
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• 2011

In this paper, a hybrid design tool combining one-dimensional(1D) lumped model and three-dimensional computational fluid dynamics(CFD) approach has been developed in order to evaluate the performance of inkjet print head and droplet control process are studied to reduce the deviations between nozzles which affect the size of the printed line for the industrial application of direct writing on printed circuit boards(PCB). 1D lumped model analysis shows that it is useful tool for evaluating performance of an inkjet head by varying the design parameters. The differences in ejected volume and droplet velocity between analytical and experimental result are within 12%. Time sequence of droplet generation is verified by the comparison between 3D analysis result and photographic images acquired by stroboscopic technique. In addition, by applying DPN process, velocity and volume uniformity between nozzles is dramatically improved that the tolerance achieved by the piezoelectric inkjet printhead across the 64 nozzles is 5 to 8%. A printed line pattern is successfully obtained using the fabricated inkjet print head and droplet calibration system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.641-647
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• 2016

A drop-on-demand inkjet is used widely for various applications. Therefore, it is important to understand the jetting behavior of the drop from the piezo inkjet. In this study, to predict the jetting behavior, VOF (Volume-of-Fluid) simulation techniques were used and compared with the experimental results. The experimentally measured meniscus movement was used as the input data for the simulation. To verify the simulation, the measured jetting behavior of the mixture fluids of ethylene glycol and IPA (isopropyl alcohol), which has a mixing ratio of 50:50, was used. The numerical simulation of the drop formation using various mixture ratios and its comparison with the measured drop formation confirmed that the proposed method can predict the actual jetting. On the other hand, the satellite drop behavior showed slight differences because the small sized droplet is subject to a more aerodynamic effect during flight because the kinetic energy of the satellite droplet is far smaller than that of the main droplet.