• Journal of KIISE:Software and Applications
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• v.34 no.5
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• pp.447-454
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• 2007

TFT-LCD(Thin Film transistor liquid crystal display) has become actively used front panel display technology with increasing market. Intrinsically there is region of non uniformity with low contrast that to human eye is perceived as defect. As the gray level difference between the defect and the background is hardly distinguishable, conventional thresholding and edge detection techniques cannot be applied to detect the defect. Between the patterned and un-patterned LCD defects, this paper deals with un-patterned LCD defects by using independent component analysis, adaptive thresholding and skewness. Our method showed strong results even on noised LCD images and worked successfully on the manufacturing line.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.697-699
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• 2004

LCD의 생산이 많아짐에 따라 LCD의 불량 검출이 중요해 지고 있다. 불랑 검사는 눈으로 확인할 수 있는 범위에서 검사가 이루어지고 있으며, 만약 눈으로 식별이 불가능한 경우 적외선 카메라나 초음파 센서를 사용하여 검사가 이루어진다. 본 논문에서는 카메라를 이용하여 LCD 패널의 표면에 있는 불량 검출을 위하여 각 Dot에 대한 R, G, B 값을 추출한 후, 추출된 픽셀을 제안된 알고리즘에 적용하여 불량을 검출하는 것을 목적으로 하고 있다.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.62-69
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• 2010

LCD panel need BLU(Back Light Unit) that is outside source of light because can not emit light voluntarily. BLU is used in LCD module and is used in tester that examine LCD panel's badness. Lately, BLU had changed from CCFL(Cold Cathode Fluorescent Lamp) to LED(Light-Emitting Diode) fast. CCFL need extra-high tension power and produce much heat and is difficult to keep fixed brightness. LED is few electric power wastage and keeps fixed brightness. But, BLU that is used to detector that examine the LCD module is using CCFL until recently. This paper develops LED BLU that can examine LCD panel's badness. Also, this manufactures LED BLU to 24 inch size to examine all LCD panels(12~24 inch), and develops so that LED BLU may operate according to LCD panel's size.

• Journal of the Institute of Convergence Signal Processing
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• v.7 no.4
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• pp.161-168
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• 2006

In this paper, we propose a method for the pattern inspection of LCD module using the color compensation and pattern matching. The pattern matching is generally used for the inspection method of LCD module at the industry. LCD module has many defections such as the brightness difference of the back light, the optic feature of liquid crystal, the difference of the light penetrated by driving LCD and the color difference by the lighting. The conventional method without the color compensation can not solve these defections and decreases the efficiency of inspecting LCD module. The method proposed to inspect defective badness through the pattern matching after it compensated color difference of the LCD occurred by the various causes. At first, it revises with setting by standard tone of color with the LCD pattern of the reference image. And It perform the preprocessing and pattern matching algorithm on the compensated image. In experiment, we confirmed that this algorithm is useful to detect some defections of LCD module. The proposed methods was easy to detect the faulty product.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10b
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• pp.426-430
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• 2006

TFT-LCD의 생산 과정에서 나오는 불량 제품의 검출은 자동화 과정에 의해 선택된 잠재적 불량 제품의 선택에 이은 인간의 목시검사에 의한 판단을 통해 이루어진다. 이러한 목시검사를 자동화하기 위해서는 불량의 식별성에 영향을 미치는 각 요소들에 대한 정량적인 분석, 그리고 각 요소들과 실제 최종적인 불량 판단 여부 사이의 체계적인 함수 관계의 파악이 필요하다. 본 논문에서는 TFT-LCD의 영역형 얼룩을 구성하는 특징적인 요소들을 정의하고, 이를 통해 불량 수준을 정의하는 수치화 함수를 유도하는 과정과, 이를 영역형 얼룩의 불량 수준 수치화에 적용한 결과를 보여 준다.

• The KIPS Transactions:PartB
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• v.17B no.6
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• pp.445-458
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• 2010

A Cold Cathode Fluorescent Lamp(CCFL) is used as a LCD Monitor's backlight widely. The most common way to check CCFL's defects is an examination with the naked eye. This naked eye examination can cause examination inconsistencies and industrial disasters. A shooting environment and detection algorithms are important for finding CCFL defects automatically. This paper presents CCFL defect detection algorithms using images captured under the shooting environment with sidelight which is one of the shooting environment we have suggested. The experimental result shows 4.65% of overdetection and 5.37% of unsuccessful defect detection of CCFL.

• Journal of KIISE:Software and Applications
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• v.34 no.11
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• pp.953-960
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• 2007

To correctly detect muras, visual defects in TFT-LCD panels, image distortion occurring on the profess of capturing panels should be corrected. In general vision systems, there are several known methods to restore the observed image. However, the vignetting effect particularly shown only in panel images cannot be easily restored through traditional methods because it is combined with background non-uniformity due to the unique characteristic of panel. To increase the reliability of image restoration, the vignetting effect should be properly corrected after being separated from image background. Therefore, in this paper we present a new method to analyze and correct the vignetting effect of panel images using principal component analysis. Experimental results for a total of 175 test images showed that the average contrast error of the muras in the distorted images was reduced from 37% to 11% and the mura misidentification rate was decreased from 14.8% to 2.2% by image restoration.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.01a
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• pp.103-106
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• 2013

3D LCD Module은 기존 TFT-LCD에 Parallax Barrier 방식과 Passive Glasses 방식 및 Active Glass 방식의 기술을 적합하여 만들어 진다. 현재는 3D Module 제작 후 기타 ASSY 장치를 부착 하여 시제품 출시 전에 3D 패턴을 기반으로 출하 검사를 통해 제품 이상 유무를 검사하다 보니 제품 출하 검사 시 불량 요인으로 불량 제품에 대한 모든 Repair공정을 위해 많은 시간 및 인력, 자재 등의 많은 로스 부분이 발생 하여 생산성 절감 및 제품 원가 상승의 요인이 발생 한다. 따라서 본 논문에서 제안하고자 하는 내용은 기존의 2D TFT-LCD Module 검사장비에 3D Pattern 및 동영상을 구현하여 보다 신속 하고 정확한 임베디드 환경을 이용한 2D 및 3D LCD Module용 검사 시스템을 개발 하는데 있다.

• Journal of the Korean Magnetics Society
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• v.22 no.3
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• pp.91-96
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• 2012

In this paper, a three-dimensional finite element model based on the multi-pixel was constructed to accurately predict electric field distributions including an interference phenomenon between adjacent pixels in the liquid crystal of a complicated TFT-LCD panel. Utilizing the elaborate numerical model, the characteristics of spatial electric field distributions depending on various fault-electrode conditions are thoroughly examined on the basis of the field distribution of a normal electrode condition. The validity of the proposed model is proved by comparing the simulation results with those of the existing optical inspection equipments.

• Journal of the Korean Data and Information Science Society
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• v.16 no.4
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• pp.823-833
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• 2005

This paper deals the TFT-LCD process and quality, process control problems of the process. For improvement of the process quality and yield, we apply a data mining technique to the LCD industry. And some unique quality features of the LCD process are also described. We describe some preceding researches first and relate to the TFT-LCD process and the problems of data mining in the process. Also we tried to observe the problems which need to solve first and the features from description below hazard must be considered a quality mining in LCD industry.