Oxide TFT-Based Micro Light-Emitting Diode Pixel Circuit for Improving Low Gray-Level Expression by Employing Sweep Generators

We propose a 16T5C oxide thin-film transistor (TFT) micro light-emitting diode (μLED) pixel circuit that enables accurate low gray-level expression by employing a sweep generator (SG) that generates a ramp-shaped sweep voltage signal within the pixel circuit. The slope of sweep voltage signal increases as the data voltage changes to low gray levels. Consequently, with decreasing gray levels, both falling and emission times are reduced. The measurement results confirm that the proposed circuit can express up to 16 gray levels, with the emission and falling times of 11.32 and 3.8 μs, respectively. Additionally, simulation results show that the circuit compensates for threshold voltage fluctuations in the driving transistor, achieving a relative average current error rate of 13% across all gray levels under a ±0.5 V variation in threshold voltage.