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This paper proposes amorphous indium–gallium–zinc oxide thin-film transistors (TFTs) four-transistor-two-capacitor (4T2C) pixel circuit in combination with a top-anode organic light-emitting diode (OLED) for the use in 8K4K active-matrix organic light-emitting diode displays (AM-OLEDs). The proposed pixel circuit compensates for driving TFTs threshold voltage (${V} _{\textsf {TH}}$) shifts and mobility variations, ${V} _{\textsf {DD}}$ current–resistance (${I}$ – ${R}$) drops, and ${V} _{\textsf {SS}}~{I}$ – ${R}$ -induced rises. Both the positive and negative ${V} _{\textsf {TH}}$ of the driving TFT can be sensed by the proposed circuit. In this paper, we analyze the impact of the driving TFT compensation time for low gray levels. The current error rates are calculated when TFT mobility variations are considered. The proposed pixel circuit allows an increase in the compensation time to reduce the impact of driving TFT ${V} _{\textsf {TH}}$ and mobility variations on the performance of 4T2C pixel circuit. Conventional two-transistor-one-capacitor, five-transistor-two-capacitor, and proposed 4T2C pixel circuits are simulated and compared in this paper. The proposed pixel 4T2C circuit reduces the current error rates to below 5.79% when the ${V} _{\textsf {TH}}$ shifts of ±2 V, mobility variations of ±10%, ${V} _{\textsf {DD}}~{I}$ – ${R}$ drops of 1 V, and ${V} _{\textsf {SS}}~{I}$ – ${R}$ rises of 1 V are all considered. We show that the proposed 4T2C pixel circuit is suitable for 8K4K AM-OLEDs. [ABSTRACT FROM AUTHOR]

This work reviews pixel circuits for blue-phase liquid crystal displays (BPLCDs) and presents two novel pixel circuits for the BPLC. With respect to the high-operating-voltage BPLC, the first developed pixel circuit comprises practical source driver integrated circuits (ICs) and an additional signal with three voltage levels to widen the voltage range from a data line in order to enable the BPLC to achieve high transmittance. For the low-operating-voltage BPLC with a large dielectric anisotropy, the second pixel circuit boosts the gate voltage of the switch thin-film transistor (TFT) to enhance its driving capability to deal with the large equivalent capacitance of the BPLC. Simulation results verify the functions of both new pixel circuits with Full High Definition (FHD, 1920\times1080) resolution and a frame rate of 120 Hz. [ABSTRACT FROM PUBLISHER]

We present a new pixel circuit on glass using hydrogenated amorphous silicon (a-Si:H) for driving polymer-stabilized blue-phase liquid crystal displays (BPLCDs). Different from conventional nematics, BPLC demands a large dielectric anisotropy in order to lower the operation voltage. As a result, the pixel's capacitance is increased by \sim\10\times, which seriously limits the charging capability and optical efficiency. Simulation results show that the average error rate of storage voltage in pixel circuit is below 5.14% for 180 Hz operating frequency. [ABSTRACT FROM PUBLISHER]