Pixel Driving Circuit for Micro LED Mura Compensation
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Solution Overview
Problem
Micro LED (μLED) display panels face issues with uneven brightness due to differences in starting voltages across LEDs, leading to the mura phenomenon, where some LEDs are not bright or overly bright, causing inaccurate brightness control and display non-uniformity.
Innovation Solution
A pixel driving circuit with a data write sub-circuit, input and read sub-circuit, drive sub-circuit, and output control sub-circuit is designed to transmit signals and generate a stable drive current, compensating for threshold voltage differences by using a storage capacitor and transistors to ensure consistent LED illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If voltage signal is directly supplied by IC to LED, then the structure is simple, but the brightness uniformity deteriorates due to different starting voltages of LEDs
Solution Approach 1:
The pixel driving circuit is divided into multiple functional sub-circuits: a data write sub-circuit for storing compensation data, a drive sub-circuit for generating drive current, and a threshold voltage compensation sub-circuit for correcting LED voltage differences. This segmentation allows each sub-circuit to perform its specific function, resolving the contradiction between structural simplicity and brightness uniformity.
Solution Approach 2:
The circuit implements feedback mechanisms where the drive transistor's gate voltage is adjusted based on stored compensation data, and the actual LED current is regulated through the drive sub-circuit. This feedback loop compensates for LED starting voltage variations, improving brightness uniformity while maintaining reasonable structural complexity.
2Ease of operation
If different starting voltages of LEDs are directly driven, then the driving method is simple, but the brightness control accuracy deteriorates causing mura phenomenon
Solution Approach 1:
The data write sub-circuit performs preliminary action by storing compensation data before the LED driving operation. This pre-compensation mechanism adjusts for LED voltage variations in advance, improving brightness control accuracy without significantly complicating the overall driving method.
Solution Approach 2:
The circuit changes the drive parameter from direct voltage control to current control through the drive sub-circuit. By converting the control mode and using adjustable gate voltages on drive transistors, the system achieves accurate brightness control despite LED starting voltage differences, resolving the contradiction between driving simplicity and control precision.
Data Source
AI summary
A pixel driving circuit, a pixel unit and a driving method therefor, an array substrate, and a display device for reducing mura phenomenon comprise: a data write sub-circuit for transmitting signals input by the data voltage terminal to a first node; an input and read sub-circuit for transmitting a signal input from a signal transmission terminal to a second node, or reading an electric signal of the second node to the signal transmission terminal; and an output control sub-circuit for transmitting a signal of a first voltage terminal to a drive sub-circuit, and transmitting a driving signal output by the drive sub-circuit to a driven circuit, wherein the drive sub-circuit outputs the driving signal under control of the signal of the first node and the signal of the first voltage terminal.