• 방송공학회논문지
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• 제18권4호
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• pp.525-534
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• 2013

최근 다양한 형태의 TFT-LCD의 수요가 증가함에 따라 LCD 생산 과정에서 얼룩결함을 검사하는 기술에 대한 관심이 높아지고 있다. 본 논문에서는 가버 웨이블렛 변환(Gabor wavelet transform) 및 이산 코사인 변환(Discrete Cosine Transform, DCT)을 이용한 TFT-LCD 패널의 얼룩(mura)을 자동으로 검출하는 방법을 제안한다. 제안한 방법은 DCT 변환 기반의 TFT-LCD 패널 영상의 참조 패널 영상을 생성한다. 원 영상과 생성된 참조 패널 영상에 대해서 실수 가버 웨이블렛 변환(real gabor wavelet transform)을 적용하여 패널 영상에 포함되어 있는 얼룩 결함을 검출하는데 방해가 되는 텍스쳐 정보를 제거하고 변환 영상간의 차영상을 이용하여 제거 결함 영역을 추출한다. 추출된 영역에 대해서는 정량적 평가 과정을 통해 보다 정확한 얼룩 검출을 수행한다. 실험결과는 제안한 방법이 기존의 방법에 비해 보다 정확하고 효율적으로 얼룩을 검출하는 것을 보여준다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.590-593
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• 2009

In the 2D local dimmable LED backlight system, each LED segment can be controlled separately. This can enhance the contrast ratio and reduce overall power consumption of LCDs. However, an artifact such as 'halo mura' can be observed around the bright object in the dark background. This is caused by the light leakage from the bright area into the dark one. Therefore, the 'halo mura' can be more easily observed in the oblique viewing direction. Thus, in this study, the perceivable degree of the halo mura is evaluated according to the level of the off-axis light leakage of LCDs. It is found that an acceptable degree of halo mura can be obtained in 2.0 cd/$m^2$ of the diagonal light leakage. In addition, the halo mura is unperceivable under 0.7 cd/$m^2$ of the diagonal light leakage which can be achieved with optimally compensated polarizers.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.841-844
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• 2007

In this paper, a vertical block mura, which massively occurred in the LCD products, was investigated extensively by various methods, source drain (SD) line shift is found out to be one of the key reasons. This work to some extent, establishes theoretic hypothesis for further research and solutions similar issues.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.426-429
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• 2005

The fringe-field switching (FFS) mode associated with a transition from a homogenously aligned to twist deformation require rubbing process. In this devices, $1^o$ of misalignment in an azimuthal direction could cause voltage-dependent transmittance (V-T) to be different from that in a normal area and consequently results in a rubbing mura. According to our studies, the single domain FFS cells are much more sensitive to the rubbing mura than the dual domain FFS cell. Moreover, the FFS cells with negative LC are much more sensitive to the rubbing mura than the FFS cells with positive LC.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1440-1443
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• 2009

We have devised a methodology based on the concept of foveal (or parafoveal) vision to investigate viewing angle related mura of a backlight unit (BLU). Three different cases of mura phenomenon in BLUs are studied with optical simulation software ASAP in this work. Simulation results, illuminance comparisons between emitting light from BLUs without and with "angle sorting" as well as experimental results are presented. They show good agreement between simulations and experimental observations that demonstrates the method's validation and robustness.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.995-998
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• 2008

Lamp mura has become a challenge for slim LCD-TV backlight design. The aim of this paper is to apply a novel diffuser plate to improve lamp mura issue instead of increasing lamps or optical films. The results are positive and contribute to the design of slimmer TV without cost up.

• 한국전기전자재료학회논문지
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• 제17권8호
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• pp.871-874
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• 2004

In recent, it is said that the trend of LCD is direction to pursue high qualities like as high transmittance, high contrast ratio, wide viewing angle, fast response time, and so on. Especially, it is known that these qualities are essential to large size LCD like as LCD TV and we can realize them through to uniform cell gap and deep black state. Until now, the ball spacer has been used to control of uniform cell gap. However, the existence of ball spacer inside the cell causes the deformation of the liquid crystal molecules and damage to alignment layer. Such a deformation of the liquid crystal causes light-leakage in the dark state, which lowers contrast ratio of the display. Nowadays, this problem has been solved by using Patterned Spacer on Color Filter. but Side Effect just as gravity mura has been induced. In this paper, we studied the mechanism on gravity mura in case of using patterned spacer on color filter.

• 대한전자공학회논문지SP
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• 제44권5호
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• pp.20-27
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• 2007

일반적으로 TFT-LCD영상은 휘도 분포가 불균일하며, 전체적으로 크게 변화하는 배경신호, 노이즈 신호, 그리고 결함 영역에서만 급격하게 변하는 결함 신호로 이루어져 있다. 본 논문에서는 HVS(human visual system)의 가장 큰 특징인 주파수에 따라 차이를 인지하는 정도가 다르다는 것을 나타내는 MTF(modulation transfer function)를 변형하여 TFT-LCD영상의 결함을 상대적으로 강조하는 알고리즘을 제안하였다. 이상적인 1차원 신호를 생성하여 제안한 방법의 유효성을 살펴보고 실제 TFT-LCD영상에 적용하여 제안한 알고리즘이 영상 결함 강조에 우수한 효과를 가짐을 확인하였다.

• 한국멀티미디어학회논문지
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• 제19권3호
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• pp.626-632
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• 2016

In this paper, we propose the defect emphasis in TFT-LCD panel image. The defect emphasis image consist of S(Shape) map and B(Brightness) map. S map based on DoG(difference of gaussian) is made with the mura defect shape characteristic. And B map use defect intensity property that defect intensity is higher than background. The experiments were conducted to evaluate the performance of the proposed defect emphasis method. The results of experiments show the validity of the defect emphasis using the proposed method.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.101-104
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• 2008

Too high stress of the bottom Mo layer of the gate line is thought to be the main reason for H-line mura. H-Line mura is eliminated effectively by changing the gate line metal structure from Mo/AlNd/Mo to AlNd/Mo. The new structure does not influence the panel's electrical characteristics.