Micro LED Pixel Drive Circuit for Luminance Consistency
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Solution Overview
Problem
Micro LED display devices face challenges with low light-emitting efficiency and inconsistent luminance at low current densities, leading to color coordinate drift and picture uniformity issues due to varying luminance across different LEDs.
Innovation Solution
A pixel drive circuit is designed with a drive sub-circuit, write sub-circuit, control circuit, and compensation sub-circuit, which includes transistors and capacitors, to control the duration and intensity of the drive current to micro LEDs, ensuring consistent luminance and gray scale control by coordinating the light-emitting control circuit and gray scale control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional driving methods are used for micro LEDs, then the device structure remains simple, but light-emitting efficiency is low and luminance is inconsistent at low current densities
Solution Approach 1:
The pixel drive circuit is divided into multiple functional sub-circuits: drive sub-circuit for current control, write sub-circuit for data input, control circuit for timing coordination, and compensation sub-circuit for threshold voltage correction. This segmentation allows each sub-circuit to optimize its function, achieving high light-emitting efficiency through precise current control while managing complexity through modular design
Solution Approach 2:
The compensation sub-circuit performs preliminary action by compensating for the threshold voltage of the drive transistor before the drive current is applied to the micro LED. This preliminary voltage correction ensures that the drive transistor operates at the optimal threshold, enabling consistent luminance output from the start of operation without requiring complex real-time adjustments
2Reliability
If conventional driving methods are used, then the circuit design is simple, but color coordinate drift and picture uniformity issues occur due to varying luminance
Solution Approach 1:
The control circuit coordinates the operation timing of all sub-circuits based on scanning signals and data signals, creating a feedback mechanism that ensures the drive transistor receives the correct gate voltage at the precise moment. This timing coordination maintains consistent luminance across different pixels and prevents color coordinate drift by ensuring uniform drive conditions
Solution Approach 2:
The compensation sub-circuit changes the voltage parameter by adjusting the gate-source voltage of the drive transistor to compensate for threshold voltage variations. This parameter adjustment ensures that despite manufacturing variations in transistor threshold voltages, all micro LEDs receive the intended drive current, achieving consistent luminance and preventing picture uniformity issues
3Manufacturing precision
If simple drive circuits are used, then manufacturing is easier, but gray scale control and luminance consistency cannot be achieved
Solution Approach 1:
By segmenting the control functionality into separate sub-circuits (drive, write, control, compensation), each sub-circuit can be designed and fabricated with optimized transistor counts and configurations. This segmentation achieves precise gray scale control through coordinated operation while maintaining manufacturing ease through modular layout and standardized sub-circuit blocks
Solution Approach 2:
The compensation sub-circuit performs preliminary voltage correction before the main drive operation, establishing the correct operating point for the drive transistor. This preliminary action enables precise gray scale control by ensuring accurate threshold voltage compensation, while the simple capacitor-based implementation keeps the manufacturing process straightforward
Data Source
AI summary
Embodiments of the present disclosure provide a pixel drive circuit, a method for driving the pixel drive circuit, and a display device. The pixel drive circuit includes: a drive sub-circuit, a write sub-circuit and a control circuit. The control circuit further is coupled to a light-emitting control signal terminal, a second scanning signal terminal and a second data signal terminal, and is configured to determine a duration of providing a driving signal to a to-be-driven element under control of a light-emitting control signal provided by the light-emitting control signal terminal and a second scanning signal provided by the second scanning signal terminal.