AMOLED Driving Circuit with Subthreshold Current Compensating Capability for High PPI Display Panel

• Main Authors: Lin,Xuan-Yong, 林玄用
• Other Authors: Tai,Ya-Hsiang
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/95442b

碩士 === 國立交通大學 === 光電工程研究所 === 104 === In this paper, we present a [novel sentinel voltage control method] of external compensating driving circuit which could mainly be applied to the active-matrix organic light-emitting diode displays (AMOLED). The pixel driving current is gradually increased by the ramp voltage at gate and converted to voltage in real time. When the sensed voltage is equal to the sentinel voltage, the gate voltage stops changing. Thus, the gate voltage is pinched at the value corresponding to the target driving current. The pixel contains only three thin-film transistors (TFTs) and one capacitor, which is suitable for high PPI display. Owing to the small area of the high PPI pixel, the operation current of driving TFT may drop down to an extremely low level. However, this compensation circuit can work for low current level, even when the TFT is operated in the subthreshold where the current exponentially varies III with its gate voltage. Although the compensation circuit can be successfully operated, there are still some issue needs to solve when it works. Hence, we proposed an advanced version of this external compensation circuit in the following chapter. Regarding to different issue, we present multiply approaches to overcome them and make the circuit design complete. Thus, using these compensation circuit can conquer the operation difficulty of high PPI AMOLED and make external driver IC work simple by pinching off signal at expected value. Along with display panels in mobile devices, wearable devices, Augmented Reality (AR) products and Virtual Reality (VR) products being indispensable tools in recent years, these techniques are sure to be widely used.