능동형 유기 발광 다이오드 디스플레이의 내장형 터치 인식 Active Area 설계에 관한 연구

Abstract

Recently, the AMOLED displays that have the touch function is in the spotlight in the display industry along with the developing the smart devices. Because AMOLED display has many advantages such as excellent color characteristic, vivid image, wide viewing angle, fast response time, low power consumption, and the slim design possibility and the touch technology makes people communicate the machine easily. However, AMOLED displays generally have the image non-uniformity by the characteristics of TFT so that many methods have been proposed to resolve the problem. The representative methods are to develop the TFT backplane and to use the compensation pixel circuit. In this thesis, I used the ASPC TFT due to the excellent uniformity of TFT characteristics and proposed the voltage programmed pixel circuit to compensate for the threshold voltage and the mobility. I also used the capacitive touch sensing method because it is suitable for the small and middle size applications and it can detect the multiple touches. Especially, the embedded touch sensing structure facilitate panel cost decrease, panel thickness decrease, brightness increase, and the easily developing the sensing IC, among others. In this thesis, I studied the design of the embedded touch sensing active area for AMOLED displays that are highly regarded as required functions in smart devices. Therefore there are the pixel circuit and the touch sensing circuit in the active area so that I proposed the pixel circuit and the embedded touch sensing circuit. First, I proposed the pixel circuit that can compensate for not only the threshold voltage but also the mobility using the voltage programming method. The simulation results show that current variations of the proposed circuit are very small in comparison with those of the conventional circuit. The proposed circuit has a simpler pixel structure than the published compensation pixel circuits so that the production yield should be improved. Second, I also proposed the embedded capacitive touch sensing circuit to realize the touch function. I realize a variable capacitor by forming the self- and/ or mutual capacitance in the TFT circuit layer. In addition, I also proposed the compensation sensing circuit to improve the touch sensitivity. This circuit can not only compensate for the threshold voltage of driving TFT but also detect the touches. The simulation results show that the proposed circuits can detect the touches by using the integrator’s output and the variation of the integrator’s output of the proposed circuit is very small.