• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.91-94
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• 2006

In this paper, in order to get micro or nano size optical patterns, an analytical and experimental investigation on a LGP (light guide plate) injection molding process has performed. The LGP, which diffusing and emitting the light from the CCFL or the LEDs to the panel front direction uniformly, typically has an under 1mm thick base substrate and numerous 60 to $170{\mu}m$ width and 6 to $10{\mu}m$ thick dot patterns on it. Generally, the small size LGPs, for mobile devices, have been and are being made of PMMA through the injection molding process. However, the substrate thickness and the dot pattern size are decreasing, it becomes hard to fill the micro to sub-micro cavities completely. To investigate the flow behavior of resin in micro/nano cavities and identify the characteristics of the LGP injection molding process, we carried out the flow analyses with respect to the variations of the substrate thickness, the dot pattern size and the pitch of a cavity.

• 한국광학회지
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• 제21권2호
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• pp.41-45
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• 2010

백라이트유닛을 더 얇고 밝게 제안하기 위하여 우리는 새로운 타입의 백라이트유닛을 시뮬레이션하였다. 도광판 상면에 미세 볼록렌즈어레이를 형성시킨다. 또한, LGP와의 매칭을 위하여 우리는 기능성 광학 시트를 시뮬레이션하였다. 일반적으로 전통적인 백라이트유닛들은 하나의 LGP와 네 개의 광학시트를 사용해왔으나 우리는 하나의 광학시트를 사용한 백라이트유닛을 시뮬레이션하였다. 설계 결과 우리의 백라이트유닛은 동일한 발광성을 달성하면서 시야각은 30% 더 좋아진 것을 밝혀내었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.693-696
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• 2009

The ray-tracing technique was used to optimize the light guide plate for the purpose of improving the on-axis luminance on the edge-lit backlights. One-dimensional prisms and engraved V-shaped patterns were applied to the upper and the lower surfaces of the light guide plate, respectively. By optimizing the apex angles of these micro-structures, as well as the shape of the reverseprism film put over the light guide plate, highly-collimated light-output distribution could be obtained on the backlight, which may contribute to the development of mobile LCD's with low power consumption.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.75-76
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• 2006

LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of kernel parts of LCD unit and it consists of several optical sheets(such as prism, diffuser and protector sheets), LCP (Light Guide Plate), light source (CCFL or LED) and mold frame. The LGP of LCD-BLU is usually manufactured by forming numerous dots with $50{\sim}200{\mu}m$ in diameter on it by erosion method. But the surface of the erosion dots of LGP is very rough due to the characteristics of the erosion process during the mold fabrication, so that its light loss is high along with the dispersion of light into the surface. Accordingly, there is a limit in raising the luminance of LCD-BLU. In order to overcome the limit of current dot patterned LGP, optical pattern design with $50{\mu}m$ micro-lens was applied in the present study. Especially, the negative and positive micro-lens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP. The attention was paid to the effects of different pattern conditions to the brightness distribution of BLU with micro-lens patterned LGP. Finally, negative micro-lens patterned LGP showed superior results to the one made by positive in average luminance.

• 소성∙가공
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• 제17권8호
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• pp.657-661
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• 2008

Recently, products of electronic industry and related parts are required to have the thickness thinner and thinner to reduce the part weight. To go with this trend, LGP(light guide plate) of LCD-BLU(Liquid Crystal Display-Back Light Unit: It is one of kernel parts of LCD) for cell phone has the thickness of ${\sim}0.3mm$ and the battery case of cell phone has ${\sim}0.25mm$. Accordingly, high speed injection molding is required to mold products which have thinner parts. To achieve high speed injection and proper control of hydraulic unit, various design was applied to conventional injection unit. In the present paper, we concentrated on the molding stability of hydro-mechanical high speed injection machine to make an LGP of 0.3mm thickness.

• Journal of Information Display
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• 제12권4호
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• pp.167-171
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• 2011

The angular distribution of the luminance on each optical component of 40-inch light-emitting diode backlight was measured and studied, using the optical-simulation method. Several scattering functions were investigated as the reflection distribution function of the scattering dots printed on the bottom surface of the light guide plate (LGP). It was found that both the diffuse Lambertian and near-specular Gaussian scattering functions were necessary for the successful reproduction of the experimental angular distribution of the luminance. The optimization of the scattering parameters included in these scattering functions led to almost the same luminance distribution as that obtained from the experiment. This approach may be an effective way of indirectly estimating the reflection distribution function of the scattering dots of the LGP, which cannot be made accessible through any other experimental method.

• 소성∙가공
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• 제20권1호
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• pp.11-16
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• 2011

Recently, according to the rapid development of display, many display applications, such as, cellular phone, navigation, monitor and LCD TV have been changed from CRT type to LCD type. BLU(Back Light Unit) is one of main parts in LCD unit and generally, it consists of a light source, a reflective sheet, a LGP(Light Guide Plate), a diffuser sheet, and two prism sheets. The most important component of BLU is a light guide plate, which diffuses the input light to the TFT-LCD module uniformly. The LGP is usually made by injection molding process, and it has numerous optical micro patterns on the surface. In the present study the micro-patterned stamper which has cylindrical shape was fabricated by using the UV-LiGA process. And the replication characteristics have been compared among three different kinds of injection molding process; general injection molding, injection/compression molding and RHCM(Rapid Heating and Cooling Molding). Average replication ratios of CIM and ICM were 19.1% and 64.6%, respectively. On the other hand, the average replication ratio of RHCM process showed the higher value of 98.4% among these. It show that maintaining the mold surface above $T_g$ could increase the replication ratio of micro patterns substantially.

• Design & Manufacturing
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• 제2권2호
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• pp.29-32
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• 2008

A back light unit (BLU) is a key module of a thin film transistor liquid crystal display (TFT-LCD), frequently utilized in various mobile displays. In this study, we experimentally characterize transcription and optical properties of concave and convex microlens arrays (MLAs) of light guide plate (LGP) fabricated by injection molding with polycarbonate as a LGP substrate material. Nickel mold inserts were manufactured by electroforming on the MLA which was fabricated by the thermal reflow of photoresist microstructures patterned by UV-photolithography. For the case of convex microlens, the height of replicated microlens was less than that of the mold insert while maintaining almost the same microlens diameter of the mold insert as the location of the microlens is far from the gate. In contrast, for the concave microlens, the diameter of replicated microlens was larger than that of mold insert, while showing almost the same microlens height as the mold insert. From the optical examination of replicated convex and concave MLAs, it was found that a higher luminance of the LGP was achieved by the concave MLAs compared to the convex MLAs (about 30% enhancement in this case)due to the utilization of a larger amount of light provided by the light sources.

• 한국위성정보통신학회논문지
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• 제9권1호
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• pp.70-73
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• 2014

최근 휴대용 정보전자기기의 비약적인 사용의 증가는 충격에 보다 강한 디스플레이에 대한 연구를 발전시키는 계기가 되었다. 일부 제조회사에서 AMOLED를 사용한 디스플레이에서 유연한 특성을 가진 제품을 선보이고 있으나, 그 사용량에 있어서 압도적으로 많은 부분을 차지하고 있는 것은 LCD 이다. 특히 LCD는 구조적인 문제로 인하여 반드시 후면광원을 사용하여야 하는데, 면발광형식의 조광장치를 얇은 두께로 구현하는데 사용되는 것이 아크릴 재질의 도광판이다. 본 연구에서는 유연하지 않은 메틸메타아크릴레이트에 부틸 아크릴레이트 고무계열의 합성재료를 첨가하여 유연성을 유지하고, 투과율을 90%까지 상승시킨 KURARITY 라는 재질을 사용한 패턴의 설계 및 성형 결과를 통해서 유연한 후면광원의 가능성을 평가하는데 주력하였다. 평가 결과 기존의 광원과 동일한 수준의 밝기 및 휘도 균일도를 얻을 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1193-1195
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• 2008

We propose a novel light guide plate for an edge-lit LED backlight. Properly designed micro-prisms enable light to go out of the LGP in near vertical direction and luminance fluctuations in front of the LEDs to be invisible.