• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.235-236
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• 2009

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.461-466
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• 2007

There has been a great interest in printing technology as a low cost and mass production method for the application of printed electronics such as printed TFT, solar cell, RFID Tag, printed battery, and so on. In this study, apparatuses of gravure-offset printing are developed for fine line-width/gap printing and examining pattern distortion occurred in gravure-offset printing process. The fine line-width/gap pattern shows that it is possible to make around 20 micro-meter line-width/gap printing patterns. Pattern distortion is modeled, and the amount and shape of the distortion are calculated by using commercial FEM code. The roll-to-roll printing system under development consists of unwinder/rewinder, two printing units, one coating unit, drying units, guiding unit, vision system, and other auxiliary devices. For multi-layer printing, the system is designed to be capable of printing two different materials.

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.05a
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• pp.19.2-19.2
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• 2008

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.9-15
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• 2013

Roll-to-roll printing technology has lately become a subject of special interests in the field of printed electronics. Since this technology has the advantage that continuous and mass production is possible. And for high precision register control is required in multi-layer printing to produce the electronic devices, this is one of the most important technologies in roll-to-roll printing technology. Register error could be generated by various reasons like eccentricity of roll and thermal deformation due to temperature variation in drying section. In this study, the effect of tension variation on the register was analyzed. The results of these analyses show that it is essential to consider the tension disturbance which is generated by the change of temperature in drying section, and conventional register model has limitation to estimate the register error. In order to overcome the limitation of the register model, advanced register model based on the SI process was developed. Also, the performance of the developed model was verified experimentally.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.9
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• pp.7-10
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• 2010

Recently, roll-to-roll printers are being developed actively by various research teams such as research institutes, universities and companies for the application of printed electronics. The printing methods that are widely used in the roll-to-roll printing equipments are gravure, gravure and flexo, which depend on the inks used and electronic devices produced. In general, a single printing unit of roll-to-roll printing equipment adopts only one printing method and this method is not changeable, which limits the application fields of the developed printing equipments. In this paper, the roll-to-roll printer, in which the printing unit has the novel design concept, is described.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.263-271
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• 2010

e-Printing is a new manufacturing technology for electronic products and is based on traditional printing technology. The electronic products require a large area to facilitate printing and to be economical. A gravure printing system that supports a roll to roll (R2R) manufacturing process can be used to reduce the cost and to achieve the required accuracy. Many factors such as drying method, drying temperature, tension,-printing velocity, ink viscosity, ink conductivity, pattern accuracy, and dot geometry influence the performance of printed electronics. These factors are closely interrelated. The optimum condition for printing must be determined to enhance the performance of the printed electronics. In this study, lines and areas are printed using a gravure printer with conductive ink under different conditions of the above mentioned factors. The results are analyzed to investigate the influence of various factors on the performance of the printed electronics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.107-108
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• 2012

• Journal of IKEEE
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• v.26 no.2
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• pp.205-210
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• 2022

We demonstrated roll-to-roll microcontact printed (mCP) microlens array (MLA) to enhance the light extraction of organic light emitting diodes (OLEDs). The commercially provided microlens array is used as a template for polydimethylsiloxane (PDMS) roll stamp. The fluorinated film is formed on the PDMS roll stamp from fluorinated ink with low boiling point and printed onto the bottom side of the organic light emitting diode without high pressure and high thermal treatment. With optimized concentration of ink, the pattern which is almost identical to that of the template MLA was successfully printed. Due to the structure and low optical absorbance of microcontact printed MLA, the external quantum efficiency of OLED was improved by about 18%.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.95-103
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• 2010

Roll to Roll (R2R) is one of the most promising production technologies in the printed electronics such as OLEDs, e-paper, backplanes, RFID because this technology can save production cost and increase production speed. Printed electronics includes various processes such as printing, drying, winding, unwinding, and so on. In printed electronics R2R system, air-flotation oven is employed for drying process. Therefore, it is essential to introduce efficient and fast drying process when printing is finished. This paper considers the analysis of drying process in R2R that involves hot air flow. Air-flotation oven consists of non-contact supports and drying of coated web materials such as plastic films and paper. In this paper, experimental results and numerical analysis of pressure-pad air bar are investigated. The aerodynamic characteristics of pressure-pad air bar are numerically calculated using computational fluid dynamics (CFD) approach. Then the measured values of the aerodynamic forces for air bars are compared with those of CFD analysis.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.6
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• pp.58-63
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• 2010

In this paper, distributed tension observer for R2R process is proposed. The minimal order observer theory is utilized to design the distributed tension observer. The proposed method estimates the tension of a specific sub-process based on the speed and tension information from its adjacent sub-processes. Utilizing its properties, the proposed method can be applied to decentralized control structure. In order to achieve high estimation accuracy, sliding mode technique is also adopted to the proposed method.