Hyung-Guel Kim

24.3: Hybrid Touch Screen Panel Integrated in TFT‐LCD

It is, for the first time, presented that the touch panel function is fully integrated in 2.45 inch amorphous silicon QVGA TFT-LCD using liquid crystal capacitive line sensor arrays with the same fabrication process as TFT-LCD. It is capable of detecting touch event and finding touch positions by the capacitance change of liquid crystal in LCD. It demonstrates outstanding display qualities and superiority in size and thickness compared to conventional resistive touch screen panel.

3.2: Integrated a‐Si Gate Driver Circuit for TFT‐LCD Panel

We developed an a-Si TFT-LCD panel with integrated gate driver circuit using a standard 5-MASK process. To minimize the effect of the a-Si TFT current and LCs capacitance variation with temperature, we developed a new a-Si TFT circuit structure and minimized coupling capacitance by changing vertical architecture above gate driver circuit. Integration of gate driver circuit on glass substrate enables single chip and 3-side free panel structure in a-Si TFT-LCD of QVGA(240*320) resolution.

35-1: Invited Paper: Advanced Technologies Based on a-Si or LTPS (Low Temperature Poly Si) TFT (Thin Film Transistor) for High Performance Mobile Display

The new technologies in mobile display developed in SEC are briefly reviewed. for a differentiation, SECs LTPS line is based on SLS (Sequential Lateral Solidification) technology. In this paper, the characteristics of SECs SLS in recent and future mobile displays were discussed. SLS has a strong point in productivity and higher performance but has a weak point in uniformity and property anisotropy. Uniformity could be improved by tilt engineering and property anisotropy by multichannel structure. By overcoming weaknesses, SLS could be basic crystallization technology for SECs LTPS mass production line. A-Si TFT technology is also important in low resolution display or mid to large size mobile applications due to its lower fabrication cost. SEC has developed successfully both a-Si and LTPS technologies as a portfolio. Cost-competitive a-Si base TFT-LCD could be developed using advanced technologies such as ASG (Amorphous Silicon Gate). For value-added functions, SEC has developed ADC(Automatic Dimming Control), h-TSP (Hybrid Touch Screen Panel) ADC can make low power consumption devices. H-TSP has two kinds of types and SEC has developed both successfully to the mass production level.

ASG(amorphous silicon TFT gate driver circuit) technology for mobile TFT‐LCD panel

Abstract We developed an a‐Si TFT‐LCD panel with integrated gate driver circuit using a standard 5‐MASK process. To minimize the effect of the a‐Si TFT current and LCs capacitance variation with temperature, we developed a new a‐Si TFT circuit structure and minimized coupling capacitance by changing vertical architecture above gate driver circuit. Integration of gate driver circuit on glass substrate enables single chip and 3‐side free panel structure in a‐Si TFT‐LCD of QVGA (240 × 320) resolution. And using double ASG structure the dead space of TFT‐LCD panel could be further decreased.

P-257L: Late-News Poster: Dynamic Simulation of Pi-Cell Liquid Crystal Displays with Transverse Field

The dynamics of a Pi-cell device that includes flow and a fixed transverse electric field is considered for the cases of static and periodic electric fields, applied vertically to the substrate of cells. The results agree with observed dynamic behavior for the case of “impulse drive”. In particular, an explanation is given for the decrease of voltage corresponding to the bend to twist director configuration and the increase of brightness when the impulse drive is applied.

Factors affecting the dynamics of a π-cell (Invited Paper)

— The basic factors related to the dynamics of a π-cell device are reviewed. Specifically, the director dynamics are studied for the case of a periodic drive voltage that is sometimes referred to as “impulse drive.” It is found for this type of drive waveform the desired bend state is more stable against the twisting effect of transverse electric fields found in AMLCD devices. This effect causes the reduction in light transmission due to “impulse drive” to be smaller in π-cell devices than is expected to be found in other AMLCD modes.

Current manufacturing technologies for TFT-LCDs

TFT-LCD panels for notebook-PC applications requires a thin and light form factor, low power consumption, and good display quality, whereas the desktop monitor has different requirements such as large panel size, wide viewing angle, high resolution, brightness, etc. However, for the fifth-generation of mass production, current panel technologies have to improve in order to cope with these requirements. In this article, various approaches to the manufacturing technologies of next-generation TFT-LCDs are discussed.