Dual-Transistor Pixel Circuit for Low-Brightness Grayscale Control

The pixel circuit is segmented into two distinct driving transistors (first driving transistor for high brightness, second driving transistor for low brightness) that independently control different brightness ranges. This segmentation allows each transistor to be optimized for its specific operating range, resolving the contradiction between simple structure and precise grayscale control by dividing the control function into specialized sub-units.

The invention transitions from a single-dimension control approach (one transistor with variable duty cycle) to a two-dimension control approach (two transistors with different current capabilities). By adding the dimension of transistor selection based on brightness range, the system achieves precise grayscale control across the entire brightness spectrum without requiring complex duty cycle modulation of a single transistor.

Different regions of the brightness spectrum are assigned different quality characteristics through dedicated transistors. The first driving transistor is optimized for high brightness regions with higher current capability, while the second driving transistor is optimized for low brightness regions with lower current capability. This local quality assignment ensures high illumination intensity when needed while maintaining precise grayscale control in the low brightness range.

The invention changes the operational parameters (current capability, threshold voltage) of the driving transistors based on the required brightness range. By selecting transistors with appropriate parameter sets for different brightness levels, the system achieves both high brightness output and precise grayscale control without the trade-off present in single-transistor designs.