Display Device Stack Structure for Color Stability
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Solution Overview
Problem
Light emitting display devices with tandem type elements face issues of color shift and aging due to gradation changes, particularly when using a white subpixel, which affects image quality and efficiency.
Innovation Solution
A display device structure is implemented without a white subpixel, using independent phosphorescent emission layers and multiple blue fluorescent stacks to combine red, green, and blue subpixels, improving color purity and efficiency, and eliminating the need for a separate white subpixel by rearranging the stack structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a white subpixel is used in tandem type elements, then white color can be displayed, but color shift and aging occur due to gradation changes
Solution Approach 1:
The emission unit is divided into multiple independent stacks (first stack with red phosphorescent emission layer and first blue fluorescent emission layer, second stack with green phosphorescent emission layer and second blue fluorescent emission layer, third stack with yellow phosphorescent emission layer and third blue fluorescent emission layer). Each stack independently emits its designated color, and white color is achieved by combining these separated color emissions rather than using a dedicated white subpixel, thereby preventing color shift and aging issues
Solution Approach 2:
Multiple color emissions (red, green, yellow, and their corresponding blue fluorescent emissions) are merged within a single emission unit to produce white light. The patent combines the emissions from different stacks (red+blue, green+blue, yellow+blue) to achieve white color display without requiring a separate white subpixel, thus maintaining color stability while achieving versatility
2Device complexity
If phosphorescent emission layers are combined in a single stack, then device complexity is reduced, but color purity decreases
Solution Approach 1:
The emission unit is segmented into three separate stacks, with each stack containing a specific phosphorescent emission layer and its corresponding blue fluorescent emission layer. This segmentation allows each stack to independently control and optimize its color emission (red, green, or yellow), thereby maintaining high color purity while managing device complexity through a systematic modular structure
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 configuration enhances color purity, reduces power consumption, and increases luminance while minimizing color coordinate changes due to aging, thereby improving overall image quality and reducing the need for a compensation driving circuit.
Implementation Method 1
at least two blue fluorescent stacks and two phosphorescent stacks configured to emit different colors of light
Implementation Method 2
two phosphorescent stacks configured to emit different colors of light
Data Source
AI summary
Disclosed is a display device including a substrate at an exit side, first to third color subpixels provided on the substrate, each of the color subpixels having a thin film transistor, first to third color filters provided respectively at the first to third color subpixels, first to third anodes provided respectively on the first to third color filters so as to be connected to the thin film transistors, an emission unit commonly provided at the first to third color subpixels on the first to third anodes, the emission unit including at least two blue fluorescent stacks and two phosphorescent stacks, and a cathode provided on the emission unit, wherein the first to third color subpixels constitute a basic unit, and a third color subpixel of an n-th basic unit neighbors a first color subpixel of an (n+1)-th basic unit in the same row or column on the substrate.