[AMD8] Advanced Driving Technology for High-quality Display

[AMD8-4] A Novel OLED Pixel Circuit with Controllable Threshold Voltage Compensation Time

*Jung Chul Kim¹, Seonghwan Hong¹, Sujin Jung¹, Mihee Sin², Jun Suk Yoo², Han Wook Hwang², Yong Min Ha², Hyun Jae Kim¹ (1. Yonsei University (Korea), 2. LG Display, Ltd. (Korea))

Keywords:High frame frequency, Moving image quality, Compensation time

This paper proposes a novel pixel circuit that adopts low temperature polycrystalline silicon thin-film transistors (LTPS TFTs) to compensate deviation of threshold voltage (V_TH) of the driving TFTs (D-TFTs) and uses overlapping compensation times (T_COM) to extend the period of precise sensing V_TH variation of the D-TFTs in each pixel. Simulation and experimental results demonstrate the proposed pixel circuit under 120 Hz Ultra High Definition (UHD) driving condition has the same compensation performance as the 60 Hz Full HD (FHD) driving condition. Therefore, the proposed pixel circuit is suitable to be used in AMOLED display with high resolution and high-frame rate and can realize uniform OLED current (I_OLED) with high immunity to V_TH variation of the D-TFTs.