• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.205-207
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• 2008

The new process for hybrid silicon thin film transistor (TFT) using DPSS laser has been developed for realizing both low-temperature poly-Si (LTPS) TFT and a-Si:H TFT on the same substrate as a backplane of active matrix liquid crystal display. LTPS TFTs are integrated on the peripheral area of the panel for gate driver integrated circuit and a-Si:H TFTs are used as a switching device for pixel in the active area. The technology has been developed based on the current a-Si:H TFT fabrication process without introducing ion-doping and activation process and the field effect mobility of $4{\sim}5\;cm^2/V{\cdot}s$ and $0.5\;cm^2/V{\cdot}s$ for each TFT was obtained. The low power consumption, high reliability, and low photosensitivity are realized compared with amorphous silicon gate driver circuit and are demonstrated on the 14.1 inch WXGA+ ($1440{\times}900$) LCD Panel.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.463-465
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• 2006

We have developed the VIC (Viewing-angle Image Control) TFT-LCD, which can change viewing-angle from $80^{\circ}$ to $170^{\circ}$. This display has the same thickness and weight as existing TFT-LCD, because it is made of only single LC cell without additional components. Moreover, we developed ways to protect effectively the displayed information in narrow viewing angle mode.

• Journal of Broadcast Engineering
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• v.18 no.4
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• pp.525-534
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• 2013

Recently, mura defect inspection techniques are receiving attention in LCD production procedure since demands of TFT-LCD are growing. In this paper, we propose an automatic mura defect inspection method using gabor wavelet transform and DCT. First, we generate a reference panel image using DCT based method. For original panel image and generated reference panel image, we apply a gabor wavelet transform to eliminate texture information in images. Then, we extract mura defect regions from the difference image between gabor wavelet transform image of original panel and generated reference panel image. Finally, all mura defect regions are quantified to detect accurate mura defects. Experimental results show that our method is more accurate and efficient than previous methods.

• Electrical & Electronic Materials
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• v.19 no.9
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• pp.28-32
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• 2006

A 7.0-inch transmissive type plastic TFT-LCD was developed at the resolution of 640 $\times$ 3 $\times$ 480 lines (114ppi). All of the processed of TFT, color filter and LC were carried out below $130^{\circ}C$ on PES plastic films. The process conditions of TFT, color filter and LC were optimized for large area TFT-LCD on plastic substrate. The backplane and the color filter was strongly adhered while the panel was bending by using holding spacers.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.964-967
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• 2009

A new hybrid-type touch screen panel (TSP) has been developed based on a-Si:H TFT which can detect the change of both $C_{LC}$ and photo-current. This TSP can detect the difference of $C_{LC}$ between touch and no-touch states in unfavorable conditions such as dark ambient light and shadows. The hybrid TSP sensor consists of a detection area which includes one TFT for photo sensing and two TFTs for amplification. Compared to a single internal capacitive TSP or an optical sensing TSP, this new proposed hybrid-type TSP enables larger sensing margin due to embedding of both optical and capacitive sensors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.797-798
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• 2012

The purpose of this study to embody LED visible light communication visual signal delivery system based on TFT-LCD module and to analyze a performance for digital signals. LED lighting enables to transmit data through light, to embody visible light communication, and to control lights in different wavelengths according to LED materials and structural materials. In this study, we aim to create a transmitting and receiving sensor that has implemented LED and visual sensors to LED efficiency and existing TFT-LCD module so as to estimate and indicate a communication distance and to find out application methods and problems. Also, by implementing TFT-LCD technology and next-generation LED visual communication technology, this study aims to check the possibility of technological realization by applying them to various means of communication including ubiquitous communication.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3429-3434
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• 2014

In the TFT-LCD(Thin Film Transistor-Liquid Crystal Display) panel manufacturing industry, SAMSUNG, a late entry, can catch up to leading first mover, SHARP. The changes the note, monitor, TV, and mobile markets in the TFT-LCD industry were studied using a system analysis method. In addition, the fast response time technology in SAMSUNG TFT-LCD technology was developed using the TRIZ method. For example, a new liquid crystal mixture of a wide view angle and fast response time were developed by doping a new high birefringence liquid crystal material in a base mixture using the contradiction method and su-field method of TRIZ. The response time of a new liquid crystal mixture was improved to approximately 60%(16.2ms with base LC mixture, 9.8ms with a new LC mixture).

• Journal of Korea Multimedia Society
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• v.13 no.8
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• pp.1115-1127
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• 2010

In order to increase the productivity in manufacturing TFT-LCD(thin film transistor-liquid crystal display), it is essential to classify defects that occur during the production and make an appropriate decision on whether the product with defects is scrapped or not. The decision mainly depends on classifying the defects accurately. In this paper, we present an effective classification method for film defects acquired in the panel production line by analyzing the intensity distribution and shape feature of the defects. We first generate a binary image for each defect by separating defect regions from background (non-defect) regions. Then, we extract various features from the defect regions such as the linearity of the defect, the intensity distribution, and the shape characteristics considering intensity, and construct a referential image database that stores those feature values. Finally, we determine the type of a defect by matching a defect image with a referential image in the database through the matching cost function between the two images. To verify the effectiveness of our method, we conducted a classification experiment using defect images acquired from real TFT-LCD production lines. Experimental results show that our method has achieved highly effective classification enough to be used in the production line.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.6
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• pp.31-38
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• 2009

To improve the image quality and lower the power consumption of the mobile applications, it is the one of the best candidate to control the backlight unit of the LCD module with ambient light. Ambient light sensor and readout circuit were integrated in LCD panel for the mobile applications, and we designed them with LTPS TFT. We proposed noble start-up correction in order to correct the variation of the photo sensors in each panel. We used time-to-digital method for converting photo current to digital data. To effectively merge time-to-digital method with start-up correction, we proposed noble dual slope correction method. The entire readout circuit was designed and estimated with LTPS TFT process. The readout circuit has very simple and stable structure and timing, so it is suitable for LTPS TFT process. The readout circuit can correct the variation of the photo sensors without an additional equipment, and it outputs the 4-levels digital data per decade for input luminance that has a dynamic range of 60dB. The readout rate is 100 times/sec, and the linearity error for digital conversion is less than 18%.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.125-129
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• 2005

Mobile display는 사용자가 이동하면서 화면을 보기 때문에 주변 luminance의 변화에 따라서 contrast ratio 변화가 심하다. 특히 햇빛 아래에서는 Mobile display의 화면을 알아보기 어렵다. 본 연구에서는 주변 조도가 증가할수록 TFT LCD의 black 휘도의 변화율이 white 휘도 변화율보다 크게 작용하여 전체 contrast ratio(이하 CR)가 크게 감소함올 확인하였다. 또한, 반투과형 LCD는 반사창을 통해서 외부 빛올 반사시키기 때문에 주변 조도가 높아도 일정 수준의 CR은 유지할 수 있다. 그러나 투과형 LCD보다 CR이 낮았다. 본 논문에서는 투과형 TFT LCD에 back light 광원으로 LED를 사용하고, photo diode와 LED drive IC를 이용하여 주변 조도의 광량에 따라서 LCD의 back light LED의 휘도를 3단계 조절할 수 있는 회로를 구성하였다. 이렇게 함으로써 주변 조도에 따라 자동으로 back light 휘도 조절이 가능한 결과을 얻었다.