Segmented Illumination Regions for Stable Display Gray-Scale Control
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Solution Overview
Problem
Conventional gray-scale control methods for LED display devices, such as current control and pulse width modulation, face issues with unstable output power, low luminous efficiency, and flickering noise, especially at low driving currents.
Innovation Solution
A display device with sub-pixels having an illumination area divided into independently controllable regions, where the gray level is determined by the total area of illuminated regions, allowing for stable gray-scale control with constant current density and reduced electrode count through shared electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If current control drive method is used to adjust driving current for luminance control, then luminance can be controlled, but output power becomes unstable and luminous efficiency is low at low driving currents
Solution Approach 1:
The illumination area of each sub-pixel is divided into multiple illumination regions that can be independently controlled. By selectively activating different numbers and combinations of these regions, the display achieves gray-scale control without requiring low current operation, thus maintaining stable output power and high luminous efficiency.
2Illumination intensity
If current control drive method is used, then luminance can be controlled, but color tone becomes unstable at low driving currents
Solution Approach 1:
Each sub-pixel's illumination area is segmented into multiple independently controllable illumination regions. This segmentation allows the display to control luminance by adjusting the number of active regions rather than reducing current, thereby maintaining stable color tone across all brightness levels.
3Illumination intensity
If pulse width modulation method is used to control luminance by changing duty ratio, then luminance control is achieved, but fine pulse-width control and high-frequency operation are difficult and flickering and noise problems occur
Solution Approach 1:
Instead of using PWM with fine pulse-width control, the patent segments the illumination area into multiple regions that can be independently activated. This spatial segmentation replaces temporal modulation, eliminating flickering and noise issues while simplifying control requirements.
Solution Approach 2:
The patent avoids periodic pulse-width modulation entirely, replacing it with a static configuration of independently controllable illumination regions. This eliminates the high-frequency operation requirements and associated flickering problems of PWM methods.
4Reliability
If illumination area is divided into multiple independently controllable illumination regions, then gray-scale control stability is improved, but device structure becomes more complex
Solution Approach 1:
Adjacent sub-pixels share common electrodes, merging their control structures. This sharing approach reduces the total number of electrodes and control lines required, thereby reducing device complexity while maintaining the segmented illumination region structure for stable gray-scale control.
Solution Approach 2:
The common electrodes serve multiple sub-pixels simultaneously, giving them multi-functionality. This universal usage of electrodes reduces the overall component count and simplifies the device structure while preserving the ability to independently control each illumination region.
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 enhances the stability of the display device's output power and color tone while reducing the risk of flickering and noise, achieving flexible and efficient gray-scale control across various illumination regions.
Implementation Method 1
The light-emitting layer disposed on the first-type semiconductor layer and configured to emit a light in response to application of a forward bias between the first-type semiconductor layer and the second-type semiconductor layer
Data Source
AI summary
A display device is provided that includes a plurality of sub-pixels. Each sub-pixel includes a light-emitting unit having an illumination area, wherein the illumination area is divided into a plurality of illumination regions, and each illumination region is configured to be illuminated independently. The light-emitting unit emits a light, and a gray level of the light is determined according to the total area of the illumination regions being illuminated.