• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.429-429
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• 2007

In this study, it was investigated about the variation of luminance properties in LED backlight with geometrical shape such as prism or lens shape on the light-entering face. Generally, LED light source has the loss in backlight system because it has horizontal direction light. PMMA(Poly-Methyl-Meta-Acrylate) is used LGP(Light-Guide-Plate) in conventional backlight system. PMMA has low refraction angle. so that. horizontal direction light was not used in backlight system. The addition of geometrical shape in light-entering face in LGP improves the luminance characteristics because it prevents horizontal direction light generation in light-entering-face. Prism or lens shape in same pitch disposition was almost same without these treatment such as the value of 1% rising. Besides. It is particular that the gap of these shape such as the value of 0.407~0.22mm prevents horizontal direction light, so then it contributes luminance rising at 5.6%.

• Korea-Australia Rheology Journal
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• v.19 no.3
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• pp.171-176
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• 2007

LCD-BLU (Liquid Crystal Display-Back Light Unit) of medium size is usually manufactured by forming numerous dots with $50{\sim}300\;{\mu}m$ in diameter by etching process and V-grove shape with $50\;{\mu}m$ in height by mechanical cutting process. However, the surface of the etched dots is very rough due to the characteristics of the etching process and V-cutting needs rather high cost. Instead of existing optical pattern made by etching and mechanical cutting, 3-dimensional continuous micro-lens of $200\;{\mu}m$ in diameter was applied in the present study. The continuous micro-lens pattern fabricated by modified LIGA with thermal reflow process was tested to this new optical design of LGP. The manufacturing process using LIGA-reflow is made up of three stages as follows: (i) the stage of lithography, (ii) the stage of thermal reflow process and (iii) the stage of electroplating. The continuous micro-lens patterned LGP was fabricated with injection molding and its test results showed the possibility of commercial use in the future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.502-503
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• 2005

본 연구에서는 TFT-LCD(Thin Film Transistor-Liquid Crystal Display)의 배경광원인 BLU(Back Light Unit)의 고효율화, 고품질화를 통한 원가 절감을 달성하기 위해 BLU의 대표적 핵심부품중에 하나인 프리즘 시트를 사용하지 않는 구조의 MNT용 BLU를 개발하는데 목적을 두었다. 고효율의 BLU를 만들기위하여 17인치 BLU의 도광판의 상, 하면에 Prism 형상을 구현하였으며, 광학적 시뮬레이션을 통하여 먼저 가능성을 검토하였고, UV에 반응하는 Resin을 경화시키는 방법을 이용하여 일반 도광판에 프리즘형상을 각인(Imprint)시키는 방법으로 실물을 재현하였다. 실험 결과 프리즘 시트를 사용하지 않는 구조의 MNT용 17인치 BLU에서 중심휘도 4,984nit, 균일도 70% 달성하였다.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.79-84
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• 2008

For the precision measurement of industrial products, the location of holes inside the products, if they exist, are often selected as feature points. The measurement of hole location would be performed by vision and laser-vision sensor. However, the usage of those sensors is limited in case of big change of light intensity and reflective shiny surface of the products. In order to overcome the difficulties, we have developed a hole displacement measuring device using contact-type displacement sensors (LVDTs). The developed measurement device attached to a robot measures small displacement of a hole by allowing its X-Y movement due to the contact forces between the hole and its own circular cone. The developed device consists of three plates which are connected in series for its own function. The first plate is used for the attachment to an industrial robot with ball-bush joints and springs. The second and third plates allow X-Y direction as LM guides. The bottom of the third plate is designed that various circular cones can be easily attached according to the shape of the hole. The developed system was implemented for its effectiveness that its measurement accuracy is less than 0.05mm.

• Transactions of Materials Processing
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• v.22 no.1
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• pp.48-53
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• 2013

As the adoption of injection molding technology increases, injected-molded optical products require higher dimensional accuracy and optical stability than ever before. In the present study, four kinds of molding methods, i.e., conventional injection molding (CIM), injection/compression molding (ICM), rapid heat and cooling the mold(RHCM) and rapid injection/compression molding (RICM) were selected in order to investigate the optical anisotropy of a 7 inch Light Guide Plate(LGP) by examining the gap-wise distribution of birefringence and the extinction angle. The results indicate that the compression process can decrease flow-induced birefringence over the whole region and that rapid heating can decrease the birefringence level better than conventional molding. In addition, for the combination of compression and rapid heating a reversal flow was detected from the distribution of the extinction angle near the gate.

• Transactions of Materials Processing
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• v.20 no.1
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• pp.5-10
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• 2011

The main objective of the present study is to predict the process window of injection-compression molding corresponding to the capability of an injection machine for fabricating 7 inch LGP. The open distance and volume filled after injection stage were found to be two important factors that affect critical requirements such as flow length, injection pressure and clamping force for the process. Process window for the key factors was also predicted by response surface method. As a result, predicted process window for open distance and volume filled after injection stage satisfying the critical requirement with a given injection machine was in the range of 60 ~ 75%, and 104.00 ~ 104.25%, respectively.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1469-1474
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• 2007

In recent years, research to machine large-surface micro-features has become important because of the light guide panel of a large-scale liquid crystal display and the bipolar plate of a high-capacity proton exchange membrane fuel cell. In this study, in order to realize the systematic design technology and performance improvements of an ultra-precision machine for machining the large-surface micro-features, a structural characteristic analysis was performed using its virtual prototype. The prototype consisted of gantry-type frame, hydrostatic feed mechanisms, linear motors, brushless DC servo motor, counterbalance mechanism, and so on. The loop stiffness was estimated from the relative displacement between the tool post and C-axis table, which was caused by a cutting force. Especially, the causes of structural stiffness deterioration were identified through the structural deformation analysis of sub-models.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1503-1506
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• 2005

This dissertation represents method concerning high performance prism LGP design in 17 inch TFT-LCD. By means of developing LGP with total size of 8mm that has prism on both upper side and bottom side, it is superior to previous printing way in gaining high brightness. It can realize actual material simulation on prism LGP production using 17inch injection process and about 20% luminance enhancement is achieved based on such method.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.265-266
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• 2008

본 논문은 기존 도광판에 복합화된 마이크로 패턴을 이용하여 휴대폰용 LCD Backlight Unit의 설계 및 해석에 대한 연구이다. 현재 상용 시제품의 도광판 패턴에 복합된 마이크로 패턴을 이용하여 광학시트를 줄이는 것을 목표로 진행 하였다. 도광판의 윗면에 프리즘형상을 설계 하였고, 아랫면은 기존의 패턴에 마이크로 패턴을 형성하였다. 마이크로 패턴의 형상은 구면, 프리즘, 실린더로 각 형상에 대해 변수를 바꾸어 가며 최적의 설계 값을 찾아보았다. 설계된 복합패턴으로 기존 Backlight Unit의 구성품인 반사판, 도광판, 확산판, BEF를 반사판과 도광판 만으로도 대체 할 수 있음을 시뮬레이션을 통해 확인하였다.

• Journal of the Semiconductor & Display Technology
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• v.12 no.3
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• pp.35-39
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• 2013

In this paper, we developed an optical sheet for LED lighting with integrated $CO_2$ gas and temperature sensor which can monitor at the indoor environment. The optical sheet for LED lighting is fabricated through PMMA(Polymethyl methacrylate) injection process using mold. This research enables to fabricate the reflective sheet, light-guide plate and the prism sheet in a optical sheet. The fabricated sheet demonstrates higher intensity of optical efficiency compared with single-sided sheets. The $CO_2$ sensor was fabricated using NDIR(NON-Dispersive Infrared) method and it has $0.0235mV/V{\cdot}PPM$ sensitivity. The temperature sensor was fabricated using RTD(Resistance temperature detector) method and it has $0.563{\Omega}/^{\circ}C $sensitivity.