Display Sub-Pixel Efficiency Mismatch for Multi-Gradation Control
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Solution Overview
Problem
Current display technologies, particularly organic electroluminescence displays (OELDs), face challenges in achieving stable multi-gradation reproduction due to the difficulty in controlling minute current values for gradation control, leading to issues with brightness variation and high power consumption, especially in large screen displays.
Innovation Solution
The implementation of an active matrix drive system with pixels comprising at least two sub-pixels of the same color, where one sub-pixel has a lower light-emission efficiency than the other, allowing for stable multi-gradation reproduction by controlling current values, thereby improving gradation control reliability and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If duty driving (time-division driving) is used to simplify panel structure, then device complexity is reduced, but power consumption increases due to decreased emission period and increased peak brightness requirements
Solution Approach 1:
The pixel is divided into two sub-pixels with different light-emission efficiencies (first sub-pixel with higher efficiency, second sub-pixel with lower efficiency). This segmentation allows the display to use both sub-pixels simultaneously for different brightness levels, enabling multi-gradation reproduction without requiring time-division multiplexing, thus reducing power consumption while maintaining simple panel structure.
Solution Approach 2:
Different regions (sub-pixels) within the same pixel are assigned different light-emission efficiency characteristics. The first sub-pixel has higher light-emission efficiency while the second sub-pixel has lower light-emission efficiency. This local differentiation enables precise gradation control by selectively activating either sub-pixel or both together, solving the power consumption issue associated with duty driving.
2Measurement precision
If minute current values are used for gradation control in active driving, then brightness precision is improved, but reliability of current control deteriorates due to TFT manufacturing variations
Solution Approach 1:
The invention changes the parameter of light-emission efficiency between the two sub-pixels rather than relying on precise control of minute current values. By having the first sub-pixel with higher efficiency and the second with lower efficiency, the system can achieve multi-gradation by selecting which sub-pixel to activate, thereby converting a current control problem into a more reliable efficiency-based selection problem that is less sensitive to TFT manufacturing variations.
3Reliability
If sub-pixels with different light-emission efficiencies are used for multi-gradation reproduction, then gradation control reliability is improved, but device complexity increases due to additional sub-pixel structures
Solution Approach 1:
The first sub-pixel and second sub-pixel are merged within a single pixel structure, sharing common electrodes and circuitry. This merging approach allows the system to achieve multi-gradation reproduction through efficient use of two sub-pixels with different light-emission efficiencies while avoiding the full complexity of completely independent pixel structures, thus balancing reliability improvement with acceptable device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables reliable multi-gradation reproduction with improved image quality and reduced power consumption, even for large screen displays, by allowing for a wider tolerance in current value variations and efficient gradation control.
Implementation Method 1
An organic electroluminescence display (OELD) is a display that emits light corresponding to electric signals and is constituted using an organic compound as a light-emitting material
Data Source
AI summary
A display by an active matrix drive in which plural pixels are controlled independently from one another, wherein each of the pixels includes at least two sub-pixels, the sub-pixels emit light of the same color as each other by application of current, and one sub-pixel of the sub-pixels has a lower light-emission efficiency per unit of current than that of the other sub-pixel. A display which has an improved gradation and is capable of multi-gradation reproduction is provided.