• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.84.1-84.1
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• 2010

Currently, new and renewable energy come into the spotlight, such as solar energy, wind power, fuel cell, hybrid car etc., due to the energy resource is being depleted. Especially, in order to solve like this problem, the study of solar cell manufacturing systems are being extensively researched such as vacuum process. But the major fault of the vacuum process are its expensive production price. On the order hand, Roll-to-roll printing system, the new technology of solar cell manufacturing, has low production price compare with the vacuum process. Also roll-to-roll printing system can decrease the 95% of waste water and 99.9% of harmful gasses than the vacuum process. So we addressed the roll to roll printing system for the flexible solar cell by using printing technology. This roll-to-roll printing system is comprised of various modules, such as web handling module, fine pattern printing module, dry/curing module, uniform coating module and laminating module etc.

• 한국생산제조학회지
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• 제22권4호
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• pp.755-760
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• 2013

The dynamics of the winder roller of a roll-to-roll printing system for printed electronics is a time-varying system because of the variation of the winder roller radius owing to rewinding or unwinding of the web. Therefore, an adaptive control method considering the time-variant characteristics is required for precise tension control. In this study, the variable PID gain method is applied to the actual roll-to-roll system and verified by experiments for unwinder tension control. The required value of the winder roller radius for the application of the variable PID gain is estimated from the measurement of the winder tension and winder motor torque. The simulation results as well as experimental results show that the fixed PID gain control cannot stabilize the tension of the winder roller with varying winder roller radius. On the other hand, the variable PID gain method can control the tension of the winder roller regardless of the winder roller radius.

• 한국생산제조학회지
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• 제25권3호
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• pp.217-223
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• 2016

In this research, a continuous roll-to-roll screen printing system was developed using a flat screen. It has a newly devised sliding mechanism of screen printing module, which can be controlled accurately in sync with a moving web, driven by a roll-to-roll tension control and web-guiding system. In addition, the real-time precision alignment module that consists of a vision camera and an $X-Y-{\theta}$ alignment stage was implemented. With this developed system, the feasibility of continuous printing with minimum pattern width below $60{\mu}m$ was verified, and an overlay of ${\pm}60{\mu}m$ between the laser-patterned reference mark and the printed mark on a 300-mm-wide film was achieved.

• 한국정밀공학회지
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• 제33권8호
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• pp.611-616
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• 2016

Computational fluid dynamic simulation based on the ABAQUS software was conducted to observe the inside flow of slot-die nozzle. The slot-die nozzle was modeled as 3-dimensional structure and three significant parameters were determined: inlet velocity of fluid, reservoir angles, number of strips none of which have been mentioned previously in the literature. The design of experiment, full factorial analysis was performed within determined design and process levels. The simulation result shows the inlet fluid velocity is most significant factor for the flows of inside nozzle. As an interaction effect, reservoir angle is closely related with number of strip that should address when the nozzle is designed. Moreover, the optimized values of each determined parameter were obtained as 35 mm/s of inlet velocity, 3 of strip numbers, and $22^{\circ}$ of reservoir angles. Based on these parameters, the outlet velocity was obtained as 0.53% of outlet uniformity which is improved from 8.67% of nominal results.

• 반도체디스플레이기술학회지
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• 제9권2호
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• pp.103-109
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• 2010

An ink transfer is modeled and experimentally verified using roll-to-roll electric direct gravure printing process. The ink transfer model based on the physical mechanism for the maximum ink transfer rate is proposed, and experimented by the electric printing machine in FDRC for the relations of the maximum ink transfer rates to the printing pressure, the operating speed, the operating tension, the surface roughness of substrates, and the contact angle between substrate and silver ink. The free ink split coefficient and immobilized ink under the maximum ink transfer rate are calculated by the physical parameter in a printing process and contact angle between substrates and ink. Numerical simulations and experimental studies were carried out to verify performances of the proposed ink transfer model. Results showed that the proposed ink transfer model was effective for the prediction of the amount of transferred ink to the substrate in a direct gravure printing systems.

• 제어로봇시스템학회논문지
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• 제15권9호
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• pp.877-880
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• 2009

A curing process in post-printing section of R2R process is required for an electrical property of the printed pattern when devices such as RFID, Solar cell are printed. PEN as well as heat-stabilized PET which is used as a plastic substrate would be deformed at high temperature due to change of its elastic modulus. And crack in the printed pattern, which is on the plastic substrate is occurred due to the deformation of the substrate. The occurrence of crack causes electrical resistance to increase and the quality of the device to deteriorate. In case of RFID antenna, the range of reading distance is shortened as the electrical resistance of the antenna is increased. Therefore, the deformation of the plastic substrate, which causes the occurrence of crack, should be minimized by setting up low operating tension in R2R process. In low tension, slippage between a moving substrate and a roller would be generated when the operating speed is increased. And scratch would be occurred when slippage is generated due to an air entrainment, which is related to the thickness of the air film. The thickness of the air film is increased when operating speed is increased as shown by simulation based on mathematical model. The occurrence of scratch in conductive pattern printed by roll to roll process is a critical damage because it causes degradation or failure of electrical property of it.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.134-138
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• 2021

스마트폰 등에서 사용되는 고성능 디스플레이에는 다양한 종류의 정밀한 플라스틱 박막 필름(Plastic Thin Film)이 사용되고 있다. 롤투롤(Roll-To-Roll) 공정으로 제조되는 플라스틱 박막 필름은 생산 공정 중에 실시간으로 필름의 두께가 계측되고, 정확하게 관리되어야 한다. 필름 제조 과정에서 필름에 장력이 작용하면서 주름이 발생되고, 이러한 주름 발생은 필름의 두께 방향과 두께 측정기의 광축이 서로 경사지게 한다. 결국 두께 측정기는 필름의 수직 두께가 아닌 경사진 두께를 측정하게 됨으로써 실제 두께보다 더 큰 값으로 측정하게 된다. 본 연구에서는, 플라스틱 필름의 경사로 인하여 발생하게 되는 두께 측정기에서의 계측값 오차를 보정하기 위하여, 필름의 경사 각도를 계측하는 연구가 진행되었다. 플라스틱 필름에 슬릿 빔 레이저를 조사하고, 필름에서 반사되는 슬릿 빔 레이저가 PSD(Position Sensitive Device)에 맺히는 광학 시스템을 구성하였으며, 실험을 통하여 필름의 경사 각도와 PSD 출력값의 관계를 1차 방정식 형태로 구하였다. 이를 이용하여 필름의 경사 각도를 측정하는 장치가 구축되었으며, 250KHz의 속도로 경사 각도의 측정이 가능하였다.

• 대한기계학회논문집A
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• 제34권3호
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• pp.263-271
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• 2010

e-Printing은 전통 인쇄 기술을 기반으로 하는 전자소자를 생산하기위한 새로운 기술이다. 이러한 인쇄 전자 소자들은 가격을 낮추기 위하여 대면적 인쇄가 요구된다. 이렇듯 원가를 절감하며 전자 소자에 요구되는 정밀도를 충족하기 위하여 롤투롤(Roll to Roll) 방식의 그라비아(Gravure) 인쇄 시스템이 하나의 대안으로 제시된다. 그라비아 인쇄에는 인쇄 전자 소자의 성능에 영향을 미치는 요소들이 매우 많다 : 건조 방식, 건조 온도, 운전 장력, 인쇄 속도, 잉크 점도, 잉크의 전도성, 망점 및 패턴의 정밀도. 이상에서 언급한 요소들은 각각 매우 밀접한 관계를 가지고 있다. 따라서 인쇄 전자소자의 성능을 향상시키기 위해서는 반듯이 인쇄 적합조건을 찾아야만 한다. 본 논문에서는, 전도성 잉크 및 그라이아 인쇄기를 사용하여 다양한 요소의 조건을 변화하여 패턴(선 및 면)을 인쇄하였으며, 각 인쇄 요소의 변화가 인쇄 전자소자의 성능에 미치는 영향에 관하여 분석 및 연구를 수행하였다.

• 한국재료학회지
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• 제18권1호
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• pp.32-37
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• 2008

The electrical, optical, structural and surface properties of an indium tin oxide (ITO) film grown on a flexible PET substrate using a specially designed roll-to-roll (R2R) sputtering system as a function of the DC power, $Ar/O_2$ flow ratio, and rolling speed is reported. It was observed that both the electrical and optical properties of the ITO film on the PET substrate were critically dependent on the $Ar/O_2$ flow ratio. In addition, x-ray diffraction examination results showed that the structure of the ITO film on the PET substrate was an amorphous structure regardless of the DC power and the $Ar/O_2$ flow ratio due to a low substrate temperature, which was maintained constant by a main cooling drum. Under optimized conditions, ITO film with resistivity of $6.44{\times}10^{-4}{\Omega}-cm$ and transparency of 86% were obtained, even when prepared at room temperature. Furthermore, bending test results exhibited that R2R-grown ITO film had good flexibility which would be applicable to flexible displays and solar cells.

• 한국재료학회지
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• 제21권5호
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• pp.255-262
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• 2011

This paper has relatively high technical standard and experimental skill. The fabrication of TCO film with high transparency, low resistance and low chromaticity require exact control of several competing factors. This paper has resolved these problems reasonably well, thus recommended for publication. Indium tin oxide(ITO) thin films were by D.C. magnetron roll-to-roll sputter system utilizing ITO and $SiO_2$ targets of ITO and $SiO_2$. In this experiment, the effect of D.C. power, winding speed, and oxygen flow rate on electrical and optical properties of ITO thin films were investigated from the view point of sheet resistance, transmittance, and chromaticity($b^*$). The deposition of $SiO_2$ was performed with RF power of 400W, Ar gas of 50 sccm and the deposition of ITO, DC power of 600W, Ar gas of 50 sccm, $O^2$ gas of 0.2 sccm, and winding speed of 0.56m/min. High quality ITO thin films without $SiO_2$ layer had chromaticity of 2.87, sheet resistivity of 400 ohm/square, and transmittance of 88% and $SiO_2$-doped ITO Thin film with chromaticity of 2.01, sheet resistivity of 709 ohm/square, and transmittance of more than 90% were obtained. As a result, $SiO_2$ was coated on PET before deposition of ITO, their chromaticity($b^*$) and transmittance were better than previous results of ITO films. These results show that coating of $SiO_2$ induced arising chromaticity($b^*$) and transmittance. If the thickness of $SiO_2$ is controlled, sheet resistance value of ITO film will be expected to be better for touch screen. A four point probe and spectrophotometer are used to investigate the properties of ITO thin films.