LTPS Pixel Driving Scheme to Improve Motion Blur for AMOLED Displays

Abstract

This article proposes a new driving scheme based on an n-type low-temperature polycrystalline silicon (LTPS) four-transistor-two-capacitor (4T2C) pixel circuit to improve the quality of motion images of active matrix organic light-emitting diode (AMOLED) displays. The proposed driving scheme can prevent the effect of the lateral leakage current flowing through the OLED common layer by keeping the pixels in the upper and lower row lines in a nonemitting hold period during the program period. The simulation results show that all RGB colors maintain a shooting amount ratio (SAR) below 1% from the first frame when the image is switched from black to white, even for a concentration of the high p-doped hole transport layer (p-HTL). In addition, the parasitic capacitances of the 4T2C pixel circuit that causes OLED current errors are thoroughly analyzed for high luminance uniformity. A 1.5-in 326 pixels per inch (PPI) AMOLED panel based on the proposed driving scheme was fabricated. The results of our measurements show that the SARs of RGB colors are 0.8%, 0.2%, and 0.9%, respectively, and the average <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${x}$ </tex-math></inline-formula> -coordinate shift of the color is 0.007 during the transition between black and white images due to the effective suppression of the lateral leakage current. Therefore, we demonstrate that the proposed driving scheme is suitable for AMOLED displays that require high-quality motion images.