Display Device Insulation Layers for Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing organic electroluminescence (EL) display devices face challenges in achieving optimal optical path lengths for color pixels, which affects light extraction efficiency and color purity, making it difficult to simultaneously increase luminance and color purity across different colors.
Innovation Solution
The display device incorporates a first insulation layer with a different refractive index than the substrate, a second insulation layer with a distinct refractive index, and organic EL elements with refractive indices matching the second insulation layer, allowing for optimal optical path lengths to be set for each color pixel by adjusting the film thickness, particularly using a planarization film to optimize interference conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If different film thicknesses are set in respective color pixels to optimize optical path lengths, then light extraction efficiency of specific colors is improved, but manufacturing complexity increases and it becomes difficult to meet conditions for both luminance and color purity across all colors
Solution Approach 1:
The patent applies local quality by introducing a planarization film with different refractive indices at different locations (first insulation layer with refractive index n1, second insulation layer with refractive index n2 where n1 < n2). This allows different regions of the display device to have optimized optical properties for different purposes: the first layer provides overall light extraction enhancement, while the second layer provides interference control for color purity, eliminating the need for different film thicknesses in each color pixel.
Solution Approach 2:
The patent changes the refractive index parameter of the insulation layers instead of changing film thickness. By using layers with different refractive indices (n1 and n2) in a stacked configuration, the patent achieves both light extraction efficiency improvement and interference condition optimization without requiring different thicknesses for different colors, thus simplifying manufacturing while maintaining performance.
2Manufacturing precision
If film thickness is adjusted to meet interference conditions for one color, then color purity is improved, but it becomes difficult to simultaneously optimize luminance and color purity for other colors with different wavelengths
Solution Approach 1:
The patent segments the insulation function into two separate layers: the first insulation layer optimized for light extraction efficiency, and the second insulation layer optimized for interference control and color purity. This segmentation allows each layer to independently optimize for its specific function, enabling simultaneous optimization for multiple colors without compromise.
Solution Approach 2:
The patent uses a composite structure of two insulation layers with different refractive indices. This composite approach combines the advantages of both layers: the first layer provides light extraction enhancement, while the second layer provides interference control. The composite structure enables the system to achieve both high luminance and high color purity across multiple colors by leveraging the complementary properties of the two materials.
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 light extraction efficiency and color purity, achieving high luminance and color reproducibility while minimizing viewing-angle dependencies and absorption issues, particularly for blue light, allowing for improved display quality.
Implementation Method 1
a first insulation layer which is disposed on a substrate with a first refractive index and has a second refractive index which differs from the first refractive index; a second insulation layer which is disposed on the first insulation layer and has a third refractive index which differs from the second refractive index
Implementation Method 2
with a first refractive index and has a second refractive index which differs from the first refractive index; a second insulation layer which is disposed on the first insulation layer and has a third refractive index
Data Source
AI summary
A display device includes a first insulation layer which is disposed on a support substrate with a first refractive index and has a second refractive index which differs from the first refractive index, a second insulation layer which is disposed on the first insulation layer and has a third refractive index which differs from the second refractive index, and a plurality of kinds of color pixels generate lights of different wavelengths, and have a refractive index which is substantially equal to the second refractive index. At least one kind of color pixel is put in contact with the first insulation layer via an opening portion that penetrates the second insulation layer.