• Transactions of Materials Processing
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• v.20 no.1
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• pp.60-63
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• 2011

BLU(back light unit) is one of kernel parts of LCD(liquid crystal display) unit. New 3-D micro-lens pattern for LGP(light guide plate), one of the most important parts of LCD-BLU, had been researched. Instead of dot pattern made by chemical etching or laser ablation, SCS(slanted curved surface) micro-lens pattern was designed with optical CAE simulation. This study introduce the method of design using optical CAE simulation for SCS micro-lens, the new fabrication method of micro-mold with SCS micro-lens pattern.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.199-202
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• 2004

CCFL(Cold Cathode Fluorescent Lamp) are used to backlight of LCD(Liquid Crystal Display). This paper presents analysis of half-bridge type resonant inverter of CCFL drive in order to stable characteristics, and fluorescent lamp operation frequency is higher than resonant frequency for safe operation. Besides, The Piezoelectric ceramic transformer (PZT) is electro-mechanical device that transfers electrical energy through a mechanical vibration. The modified equivalent circuit model of the PZT considering the operating current level is derived to design the CCFL. The validity of this study was confirmed from the simulation and experiential result.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.222-223
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• 2011

최근 저전력 소모와 얇은 두께, 무 수은, 다양한 색 표현력, 빠른 응답 속도 등의 다양한 장점을 가진 LED(Light Emitting Diode)를 광원으로 이용하는 LCD(Liquid Crystal Display) TV가 큰 주목을 받고 있다. 이러한 LCD TV의 화면을 균등한 휘도로 표현하기 위해 기존의 구동회로는 다 채널의 LED를 정전류로 제어하는 DC/DC 컨버터가 채널마다 각각 적용되었고, 이는 원가 상승 및 효율 저하의 원인이 되었다. 이를 해결하기 위하여 본 논문에서는 각 LED 채널에 적용되는 DC/DC 컨버터 없이 트랜스포머, 커패시터, 다이오드를 이용하여 모든 LED 채널의 정전류 제어가 가능한 저가격형 구동회로를 제안한다. 이는 전력변환 효율과 전력밀도를 획기적으로 개선할 수 있고 수동소자만을 사용하므로 높은 신뢰성을 확보할 수 있다. 본 논문에서는 제안된 회로에 대한 이론적 해석과 실험을 통해 제안 회로의 타당성을 검증한다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.241-244
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• 2004

Microlens patterned micro-mold fabrication method for Light Guiding Plate(LGP), kernel part of LCD-BLU(Back Light Unit), was presented. Instead of erosion dot pattern for LCP optical design, microlens pattern, fabricated by LIGA-reflow process, was applied. Optical pattern design method was also developed not only for negative pattern LGP, but also positive pattern LGP. In order to achieve flow balance during the micro-injection molding process and dimensional accuracy, two LGP pattern was made in one micro-mold.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.723-728
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• 2006

In this paper, we present a new system, OPTISCOPE SA, especially designed for precise measurement of temporal behavior of LCD displays. We show that gray to gray level response time measurement requires a very sensitive and precise instrument and also that the capacity to measure luminance levels and gamma curve can be useful. Quite often, precise evaluation of LCD response time needs also use of low pass and stop band filters to suppress noise and flicker. Low pass filters affect the results but can be corrected for simple temporal behaviors. For complex temporal behaviors like those observed for overdriven LCDs, we show that direct adjustment of theoretical responses is much more efficient to get a complete picture of the temporal behavior of such displays.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.826-829
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• 2006

In order to increase the transmittance of panel, in process of FFS TFT-LCD, fine patterning process which is adopted to the optimum passivation(PVX) hole was applied fine metal line patterning process and was made with optimum efficiency of liquid crystal by using space/bar size control of pixel electrode. We fabricated 2.03" mobile FFS devices with fine patterning process. Further, this technology will be applied to the basis of other process for higher PPI or higher aperture ratio technology.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.1
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• pp.88-93
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• 1988

For coherent optical information processing the thickness uniformity of the spatial light modulators(SLMs)is highly demanded. The liquid crystal display(LCD), which is commercialized as a pocket-sized television, is considered as one of the most cheap 2-dimensional SLM. But usually it has lack of thickness uniformity. Thus phase correction to compensate the thickness nonuniformity must be preceded before it is used as an SLM. In this paper relatively easy phase compensation method applicable to binary SLMs is discussed and experimentally verified by using the optical joint transformantion concept.

• Journal of the Optical Society of Korea
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• v.13 no.2
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• pp.256-260
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• 2009

The optical performance of the reflective polarizer was investigated over three kinds of direct-lit backlights and/or different configurations of the optical sheets. The optical gain factor achieved by using the reflective polarizer increased as the diffuse nature of the optical sheet was enhanced, because of the more efficient polarization conversion. In addition, the gain factor decreased substantially in flat-lamp backlights compared to tubular-lamp backlights, which was ascribed to the high loss factor during the polarization recycling process due to the complex structure and large area of flat lamps. All these results suggested that reducing the loss factor of the backlight is very important for efficient polarization conversion and thus high optical gain of the reflective polarizer.

• Journal of the Optical Society of Korea
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• v.17 no.3
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• pp.275-278
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• 2013

The effect of the wavelength-dependent scattering on the change of the color chromaticity in the lightguide panel of a liquid crystal display is examined. The white light emitted from the white LEDs located at the edge of the lightguide propagates in the lightguide and is scattered by the patterned dots that are placed on the bottom of the lightguide. The scattered lights that are far from the LEDs showed reddish color compared to the bluish color that is scattered from the near area from the LEDs. The color difference was between 0.01 to 0.06 depending on the resin and the thickness of the lightguide.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.906-907
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• 2008

기존의 LED(Light Emitting Diode)를 이용한 LCD(Liquid Crystal Display) 백라이트 유닛은 무부하시 불필요한 전력소모가 발생하는 경우가 있어 보호회로가 필요하였다. 그래서 본 논문은 보호회로를 이용한 LCD 백라이트 유닛용의 LED 구동회로를 제안한다. 제안된 보호회로는 실험 결과 무부하시 피드백 제어부 IC(Integrated Circuit)의 전원전압 VCC를 UVLO(Under Voltage Lock Out)전압 이하로 강하시켜 무부하시 소비되는 전력을 줄일 수 있었다. 또, 무부하시 부스트 컨버터 출력부의 전압스트레스를 줄일 수 있었고, 유부하시 보호회로가 있는 컨버터와 보호회로가 없는 컨버터의 효율비교에서 거의 같은 효율이 측정되었다.