• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.269-272
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• 2008

LGP is a key component of LCD back light unit because it determines the brightness and sharpness of display image. Usually, it has optical patterns fabricated on the bottom surface. In the present paper the LiGA-reflow method was applied to fabricate the LGP mold. Furthermore, the optical simulation considering the replication ratio of pattern height was applied to the pattern design. The optical simulation through systematic correction scheme helped find the optimum distribution of pattern density. Finally, the stamper fabricated by this method was installed in the mold and LGP was produced by injection molding. As a result of luminance measurement for the final product, the average luminance and luminance uniformity was measured 3,180 nit and 84%, respectively. Consequently, the mold fabrication method using the LiGA-reflow and optical simulation(CAE) can save the expense and time compared with the existing fabrication methods(laser ablation and chemical etching).

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.136-136
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• 2010

일반적인 플라즈마의 밀도측정에는 랑뮤어(Langmuir)탐침법이 보편적으로 사용되고 있다. 그러나 LCD(Liquid Crystal Display)나 PDP(Plasma Display Panel) 등 미세 방전 플라즈마는 이러한 방법으로는 측정이 너무 어려워서 잘 사용되지 않고 있다. 그래서 이러한 경우 간접측정 방법이 사용되고 있다. 본 연구에서는 알려진 간접 측정방법과는 다른 방식인 spectrum analyzer를 사용하여 측정해 보았다. LCD에서 사용되는 BLU(Back Light Unit)lamp와 PDP panel을 각각 측정하여 기존의 간접측정 방법의 결과와 비교해 보았다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.422-425
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• 2008

Recently, electronic products and related parts are required to have thin thickness because of small form factor. To go with the 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 0.3 mm and the battery case of cell phone has 0.25 mm. Accordingly, high speed injection molding is required to make products which have thin thickness. High speed injection molding means that the resin is injected into the cavity at higher than normal speed avoiding short shot. In the case of hydro-mechanical high speed injection machine, it requires the design for hydraulic unit to make high injection speed and the design for control unit to control hydraulic unit. In the present paper, we concentrated on the molding stability of hydro-mechanical high speed injection machine to make an LGP of 0.3 mm thickness.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.5
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• pp.218-223
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• 2013

In this study, the reflectivity characteristics of Ag nano-coating grown by electroless plating were investigated in order to use as the reflecting plate of BLU (Back Light Unit) in the LCD (Liquid Crystal Display) or LED (Light Emitting Diode) display equipment. The microstructure of Ag nano-coating was polycrystalline nano-structure that consisted of Ag nano-crystals to be reduced and precipitated, and the size of reduced nano-crystals increased as the thickness of nano-coating increased. The reflectivity of Ag nano-coating in the visible light decreased as the thickness of nano-coating increased and the reduction of reflectivity was more severe in the short wavelength region of visible light. The decrease of reflectivity was closely related to the size of Ag nano-crystal and was thought to be due to the larger surface roughness of larger nano-coating thickness. Therefore, the finer Ag nano-crystals and thinner nano-coating thickness could be favorable for the higher reflectivity of Ag nano-coating grown by electroless plating.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.99-102
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• 2009

The recent LCD TV market has made efforts to produce thinner, brighter, and clearer products, and experienced the rapid light source replacement from a line source of light CCFL to a point source of light LED. In particular, LGP(Light Guiding Panel) among key parts composing BLU(Back Light Unit) has limits of the injection molding technology as well as the mold design, its processing and manufacturing technology so that it is hard to produce large LGP over 40 inch. To produce large light-guide panels over 40 inch under the injection molding process, a mold 3D model was developed in the design process before manufacturing a mold and structure unification was processed through CAE analysis. As a result, it was possible to construct the mold design process, and it is expected to manufacture the optimized mold by applying the mold design and manufacturing process of large-scale rapid injection-compression molding that will be produced in the future.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.661-667
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• 2008

In this study, cholesteric liquid crystal (CLC) was synthesized and applied as a polarizing component on the optical film of back light units (BLU) for LCDs. After mixing CLC with nematic liquid crystal, this mixture was fulfilled in the module consisting of two films and then its amplifying efficiency and polarizing ability for a planarly emitted light were examined to apply as a BLU polarizer film for increasing the brightness of light. The properties of CLC compound were tested by UV/Visible spectroscopy and polarizing optical microscopy (POM). Flexible spacer was made by linear carboxylic acid group of cholesteric derivatives between cholesterol mesogen units for one-axis orientation in each layer. The CLC containing film could be used as a module to increase the ability of polarization and to enhance brightness of BLU and to widen wavelength range by stacking the films.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.7
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• pp.761-768
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• 2011

The large surface micro machining system includes the equipments and processes for manufacturing the ultra precision micro patterned products with large surface through the mechanical machining. Recent major issue on the micro machining technology may be the development of optical parts for the back light unit of display which has the largest market. This special issue makes up with three parts; the large surface micro machining system and machine, machining process and forming process. In this paper, the state-of-the-art and core technology of large surface micro machining system is introduced with focus on the manufacturing technology for the back light unit of LCD TV. Then, some research results on the development of a roll die lathe is introduced which involves the concept of machine design, improvement of thermal characteristics in the spindle system, improvement of relative parallelism and straightness between spindle system and long stroke feed table, machining of micro pitch patterns. Finally, the direct forming process is introduced as the future work in the large surface micro machining field.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.4
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• pp.521-528
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• 2010

A product system will be improved continually until requirements are satisfied. It is true that considering alternative designs to improve product system is hard work; it is also true that selecting an adequate design idea that represents the needs of stakeholders concerned and meets effectiveness factors properly is not an easy work, either. In the process of driv-ing an idea and designing, which is called Design Phase, there are lots of existing tools for testing the driven idea in DFSS. But, those kinds of tools do not offer the function that helps to select the technically better design idea among alternative design ideas that have the same evaluation level. Moreover it is inappropriate to select adequate alternative design ideas by just verifying only the evaluation table in pugh matrix, since satisfied deviation val-ues are low when there is a too competitive mass product system in a market. Also, for the IT product with short life cycle, faster and more effective testing tool is needed. Therefore, the 'roduct quality index' is suggested in order to select an appropriate candidate design concept for system development that meets requirements by using 'deality concept' pro-vided by TRIZ. According to the result of this research, it is possible to select technically better idea fast and effectively; it is confirmed by applying the approach to the case of LCD BLU (Back Light Unit).

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.759-762
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• 2005

The LGP(Light Guide Panel) for the back light unit that is used to the 2.2" TFT LCD was designed and fabricated. The method of the pattern design which is the most important in the design of the LGP was converted the V-cutting method into the Dot method. This newly developed Dot method provided a good uniformity in the brightness at the LGP, which was a very difficult problem to solove in the V-cutting method. The experiment result of the newly designed LGP shows the brightness uniformity 90% and the brightness 3656 $cd/\;m^2$ which is 20% higher than the commercial products.

• Proceedings of the KIEE Conference
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• 2008.05a
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• pp.167-168
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• 2008

Organic light emitting diodes (OLEDs) show a lot of advantages for display purposes. Because OLEDs provide white light emission with a high efficiency and stability, it is desirable to apply OLEDs as an illumination light source and back light in LCD displays. We synthesized new emissive materials, namely $Zn(HPB)_2$ and Zn(HPB)q, which have a low molecular compound and thermal stability. We studied white OLEDs using $Zn(HPB)_2$ and $Zn(PQ)_2$. The fundamental structures of the white OLEDs were ITO / NPB (40 nm) / $Zn(HPB)_2$ (40 nm) / $Zn(PQ)_2$ (20 nm) / LiAl (120 nm). As a result, we obtained a maximum luminance of $4200cd/m^2$ at a current density of $440mA/cm^2$. The CIE (Commission International de l'Eclairage) coordinates are (0.319, 0.338) at an applied voltage of 10 V.