• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.43-47
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• 2008

Nowadays, the pattern size of BLU (Back Light Unit) adopted in TFT-LCD (Thin Film Transistor Liquid Crystal Display) is typically a few tens of micrometers. However, recently, researches on the TFT-LCD output characteristics depending on various types of BLU patterns are being performed in order to improve the output and uniformity. In this study, we analyzed the influence of pattern size, distribution, and areal ratio on the output characteristics.

• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.259-264
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• 1999

The relationship is derived for color CRT display system between the spectral radian existence emitted and digital inputs. The amount of spectral radiant existence depends on the characteristics of the video board, electric circuits, and CRT as well as digital inputs. Especially, the function of this relationship changes as the amplifier gain and offset voltage of electric circuits. In this study, we set the test display system on the optimum state which satisfies gun independence characteristics by using the contrast and the brightness controls of display. Temporal stability, special uniformity, and color distinction of CRT display system are evaluated at the optimum state. Also contrasts in dark room and illuminated room are compared.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.2
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• pp.15-19
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• 2007

A 15[inch] diagonal mercury-free flat discharge lamp with insulated electrode has been developed as backlight for a LCD backlighting. When the drive voltage pulse conditions were set properly, a uniform and stable discharge extends over the entire volume. It was obtained luminance of $10,330[cd/m^2]$ without prism sheet in uniform and stable discharge.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.4 s.334
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• pp.53-60
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• 2005

This work Proposes and describes an LCD backlight driver IC using a voltage feedback circuit which improves the brightness uniformity. The proposed circuit controls the brightness of a backlight by amplifying of sampling voltage at a lamp. To keep the uniformity of brightness, the circuit has a reference lamp. The output voltage of the reference lamp is supplied commonly to each lamp that reduces a resistance deviation of the lamps. As a result, the proposed circuit shows brightness uniformity improvement of about $40\%$ compared to the conventional ones.

• Korean Journal of Optics and Photonics
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• v.19 no.2
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• pp.122-126
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• 2008

Dual backlight unit incorporating a single light source integrated with a beam splitting reflector was demonstrated, providing a surface light beam for both the keypad and the display section simultaneously. The reflector was realized by aligning a groove substrate with a matching cover, and a light guiding module comprising a stack of light guide panels and prism/diffuser sheets was attached to both sides of the reflector. A light emanating from the light source-placed in the middle of the substrate-undergoes a series of reflections through the reflector to reach the input of the light guiding module. Then it is transformed into a surface light beam, which is used to irradiate the keypad and display sections simultaneously. As for the accomplished dual surface light sources, the measured average luminance and the spatial luminance uniformity were respectively about $420\;cd/m^2$ and 69% for the keypad section, and $640\;cd/m^2$ and 79% for the display section.

• Korean Journal of Optics and Photonics
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• v.28 no.6
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• pp.314-326
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• 2017

The display, which is closely related to modern life, is being developed as a window on a network connecting individuals, devices, and even other individuals from simple display devices, as the IT industry develops. To achieve a thinner, brighter unit with less consumption for backlighting, the LED light source has applied, and the study of complex light-guiding plates to improve luminance, uniformity, and viewing angle has been initiated. In this paper, we summarize the research results for the scatterers' pattern formation of the light-guiding plate and the arrangement and composition of the light source, which have enabled remarkable development of the LED backlight unit over the last 10 years. In addition, a large-area flat-screen illumination system, applying the light-guiding-plate technology to a currently noteworthy LED light-fixture design, is outlined. Finally, we discuss the direction and way to develop the current technology more progressively.

• Journal of the Korean Vacuum Society
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• v.16 no.3
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• pp.172-180
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• 2007

A new diagnostics of plasma electron temperature and plasma density is introduced with the observation of the light emission along the tube of external electrode fluorescent lamps. With two different methods operating an external electrode fluorescent lamp of outer diameter 4.0 mm and length 860 mm for the back-light source of 37-inch LCD-TVs, the lighting modes and the plasma properties are investigated. In the center balance operation, the light-emission propagates simultaneously from both sides of the high voltage electrodes to the center of the lamp, while in conventional operation the light-emission propagates from the one end of a high voltage to the other ground electrode. In the operation value of luminance $10,000{\sim}15,000cd/m^2$, the electron plasma thermal energy $(kT_e)$ is about $1.3{\sim}2.7eV$ with the electron density $(n_e)$ is about $(1.6{\sim}3.6){\times}10^{16}m^{-3}$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.1-9
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• 2009

Impact of daylighting on the visual environment can improve occupant's well-being by providing visual comfort. Also, daylighting can save energy. However, glare from window can be a direct hazard to vision and can cause serious discomfort. Selecting glare source on a window plane is very important for evaluating discomfort glare from windows. But former glare indices can not identify the range of the glare source properly. In this study, difference in glare sensation with uniform and non-uniform glare sources are evaluated to identify the range of the glare source. The glare source was assumed as $120{\times}120[cm]$ window model. The window was divided into three parts with different luminance values. The experiment was conducted under 1[m], 1.5[m], 3[m] distance from the glare source. Two results were obtained from the experiments. First, the degree of discomfort glare increased as average window luminance increased. Second, the middle and lower part of the window plane can affect evaluation of discomfort glare as well as the upper part of the window plan. These results can be used for selecting the glare source in a window with non-uniform luminance.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.501-501
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• 2013

유기발광소자는 빠른 응답속도, 넓은 시야각, 얇은 두께의 특성으로 차세대 디스플레이 소자기술로 많은 주목을 받고 있다. 특히 높은 색순도와 고효율의 장점을 가지는 양자점을 사용한 유기발광소자에 대한 연구가 활발하게 진행되고 있다. 양자점을 이용한 유기발광소자는 용액 공정이 요구 되기 때문에 유기물 박막 위에 양자점을 균일하게 도포하기 어렵다. 또한, 양자점은 수분과 산소에 빠르게 열화되는 문제점이 있다. 본 연구에서는 색변환 양자점을 포함하는 고분자 poly (N-vibylcarbazole) 정공수송층을 용액공정으로 형성한 후 발광층, 전자 수송 및 주입층과 음극을 차례로 진공증착하여 색변환 양자점을 포함하는 정공수송층을 적용한 청색 유기발광소자를 제작하였다. 색변환양자점과 청색 발광층으로 a 1,4-bis (2,2-diphenylvinyl) biphenyl를 사용하여 제작된 유기발광 소자의 전기적 및 광학적 특성을 관찰하였다. 색변환 양자점을 포함한 청색 유기발광소자의 경우 정공이 양자점에 포획되는 확률이 낮기 때문에 높은 전류밀도와 휘도를 나타냈으며, core/shell 색변환 양자점을 포함한 청색 유기발광소자는 정공이 양자점에 포획되는 확률이 높기 때문에 낮은 전류밀도와 휘도를 나타냈다. 한편, core/shell 색변환양자점을 포함한 청색 유기발광소자의 경우 색변환 양자점을 포함하는 청색 유기발광소자에 비해 발광층에서 발광된 빛을 잘 흡수하여 높은 색변환 효율이 나타났다. 이 연구 결과는 양자점을 색변환층으로 사용한 청색 유기발광소자의 색변환 효율 증가와 발광효율 향상에 대한 기초자료로 활용할 수 있다.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.1-8
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• 2007

A flat fluorescent lamp (FFL) was developed as a light source for LCD TV Backlight. The channels of FFL were realized by forming the flat glass at high temperature. The performance of the backlight with FFL was shown to improve by optimizing the FFL channel profile that has elliptical shape, 4.4 mm height and 1.4 mm sealing distance. In this paper, the brightness uniformity of LCD TV backlights was investigated by optical simulation of FFL channel profiles. The brightness of LCD TV using FFL with the optimized channel profile was shown to be $576\;cd/m^2$.