• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.1
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• pp.3-9
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• 2009

Although Active matrix organic light emitting diode (AMOLED) display has a better image quality in terms of viewing angle, contrast ratio, and response time than liquid crystal displays (LCDs), it still has some critical issues such as lifetime, residual images, and brightness non-uniformity due to non-uniformity in electrical characteristics of driving TFTs and IR drops on supplied power line. Among them, we improved irrecoverable residual images of AMOLED displays which is mainly related to the hysteresis characteristics of driving TFTs. We consider four kinds of surface treatment conditions before gate oxide deposition for improving hysteresis characteristics. We can reduce the hysteresis level of p-channel TFT to 0.23 V, interface trap states between the poly-Si layer and gate insulator to $3.11{\times}10^{11}cm^{-2}$, and output current variation of p-channel TFT to 3.65 % through the surface treatment using ultraviolet light and H2 plasma. Therefore, the recoverable residual image problem of AMOLED displays can be improved by surface treatment using ultraviolet light and $H_2$ plasma.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1030-1033
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• 2005

Today's most equipments that contain embedded system only support simple menus and background graphics. However, as the embedded system is applied for much more various fields and the user's needs for graphical interface become higher, the support for multimedia and moving pictures became an important criterion to evaluate the performance of a equipment. Because the present embedded system uses software to construct display environment, it is difficult to meet the bandwidth for multimedia contents and moving pictures. Using software for graphic also lowers the performance of the main function by overloading the processor. In this paper, we present an OLED/TFT-LCD controller suitable for embedded systems. The architecture we propose is described in HDL and the performance is evaluated in comparison with the existing embedded systems.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.3
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• pp.323-329
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• 2009

This paper presents an automatic LCD gamma control system using gamma curve optimization. It controls automatically gamma adjustment registers in mobile LCD driver IC to reduce gamma correction error and adjusting time. The proposed gamma system contains Module-Under-Test (MUT, LCD module), PC installed with program, multimedia display tester for measuring luminance, and control board for interface between PC and LCD module. Proposed algorithm and program are applicable for most of the LCD modules. It is realized to calibrate gamma values of 1.8, 2.0, 2.2 and 3.0. The control board is designed with DSP and FPGA, and it supports various interfaces such as RGB and CPU. Developed automatic gamma control system showed significantly reduced gamma adjusting time of 240 sec. and much less average gamma error of 11% than 42h and 27% with conventional manual method. We believe that the proposed system is very useful to provide high-quality LCD and to improve production process.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.700-702
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• 2005

A 5.0-inch transmissive type plastic TFT arrays were successfully fabricated on a plastic substrate at the resolution of $400{\times}3{\times}300$ lines (100ppi). All of the TFT processes were carried out below $150^{\circ}C$ on PES plastic films. After thin film deposition using PECVD, thin film failures such as film delamination and cracking often occurred. For successful growth of thin films (about 1um) without their failures, it is necessary to solve the critical problem related to the internal compressive stress (some GPa) leading to delamination at a threshold thickness value of the films. The Griffith's theory explains the failure process by looking at the excess of elastic energy inside the film, which overcomes the cohesive energy between film and substrate. To increase the above mentioned threshold thickness value there are two possibilities: (i) the improvement of the interface adhesion (for example, through surface micro-roughening and/or surface activation), and (ii) the reduction of the internal stress. In this work, reducing a-Si layer film thickness and optimizing a barrier SiNx layer have produced stable CVD films at 150oC, over PES substrates

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2071-2077
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• 2010

Interface modules design between image sensor and external components are designed by FPGA (Field Programmable Gate Array) in this paper. Generally speaking, to satisfy synchronization for the poor quality data in image, SRAM is needed. To receive synchronization signal and image signal data with pixel dimension, the proposed interface logic technique is implemented. From the proposed technique, we can obtain more clear screen by implementing with pixel dimension. Operating frequency of image sensor and that of TFT-LCD are 50MHz and 6.5MHz, respectively. Most of control logic functions are embedded in FPGA. The designed logic gate counter has 33,216 and is designed by Quartus II.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.6
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• pp.473-479
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• 2011

In this paper, we have compared amorphous InGaZnO (a-IGZO) thin-film transistor (TFT) with the nano-crystalline embedded-IGZO ($N_c$-embedded-IGZO) TFT fabricated by solid-phase crystallization (SPC) technique. The field effect mobility (${\mu}_{FE}$) of $N_c$-embedded-IGZO TFT was 2.37 $cm^2/Vs$ and the subthreshold slope (S-factor) was 0.83 V/decade, which showed lower performance than those of a-IGZO TFT (${\mu}_{FE}$ of a-IGZO was 9.67 $cm^2/Vs$ and S-factor was 0.19 V/decade). This results originated from generation of oxygen vacancies in oxide semiconductor and interface between gate insulator and semiconductor due to high temperature annealing process. However, the threshold voltage shift (${\Delta}V_{TH}$) of $N_c$-embedded-IGZO TFT was 0.5 V, which showed 1 V less shift than that of a-IGZO TFT under constant current stress during $10^5$ s. This was because there were additionally less increase of interface trap charges in Nc-embedded-IGZO TFT than a-IGZO TFT.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.695-698
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• 2006

The photosensitive poly-siloxane material used as the passivation layers for the conventional back channel etched (BCE) thin film transistors (TFTs) has been investigated. Through the organic material, the TFT array fabrication process can be reduced and higher aperture ratio can be achieved for higher LCD panel performance. The interface between the organic passivation layer and the back channel of the amorphous active region has been improved by the back channel oxygen treatment and the devices exhibits lower leakage current than the conventional silicon nitride passivation layer of BCE TFTs. The leakage currents between Indium-tin-oxide (ITO) pixels and the TFT devices and its mechanism have also been investigated in this paper.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.10
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• pp.489-493
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• 2001

The on-current of offset and LDD structured devices in slightly decreased while the off-current are remarkably reduced and almost constant independent of gate and drain voltage because offset and LDD regions behave as a series resistance and reduce the lateral electric field in the drain depletion. Degradation of these devices is dependent upon the offset and LDD length rather than doping concentration in these regions. Also, degradation mechanism has been related to the interface generation rather than the hot carrier injection into gate oxide.

• Journal of Information Processing Systems
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• v.3 no.1
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• pp.16-20
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• 2007

This paper describes the development of the sensor interface and driver program for a point of care (POC) device. The proposed pac device comprises an ARM9 embedded processor and eight-channel sensor input to measure various bio-signals. It features a user-friendly interface using a full-color TFT-LCD and touch-screen, and a bluetooth wireless communication module. The proposed device is based on the system on a programmable chip (SOPC). We use Altera's Excalibur device, which has an ARM9 and FPGA area on a chip, as a test bed for the development of interface hardware and driver software.

• The KIPS Transactions:PartA
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• v.10A no.1
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• pp.69-74
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• 2003

Accurate process control in the manufacturing industry is essential to survive in the competitive market. Statistical process control (SPC) system has been widely used to satisfy the ever-increasing quality control requirements. However, most commercial products in the market are not flexible, semi-automatic, and difficult to interface with other tools. In this paper, we propose an advanced rSPC (Real-Time SPC) system which is based on the web and supports XML protocol. We also provide a powerful graphic facility and an efficient file system to handle the data in real time. Even though the idea can be applied to any manufacturing system, our system is optimized to the semi-conductor industry and TFT/LCD industry. The system is implemented in C++ and COM/DCOM, and shows a good result.