Novel Pixel Circuit Using Coupling Method to Achieve High Driving Voltage for Blue-Phase LCDs

This paper presents a new pixel circuit that uses amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs) for use in in-plane switching blue-phase liquid-crystal displays (IPS BPLCDs). The proposed pixel circuit has a simple structure that involves only three TFTs and two capacitors. To drive the high transmittance of the BPLCs, the coupling mode with a two-voltage-level signal is designed to produce a higher operating voltage. To confirm the feasibility of the proposed pixel circuit, the electrical characteristics of a fabricated a-IGZO TFT are measured and used to construct the RPI simulation model in HSPICE. Simulation results demonstrate that the maximum operating voltage is 29.884 V with an input data voltage of 15 V, so the required voltage of high transmittance of BPLCs is achieved.