Color Conversion Sheet Layering for Uniformity and Durability
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Solution Overview
Problem
Existing color conversion sheets for displays and lighting devices face issues with in-plane uniformity and durability, leading to variations in color tone and luminance, particularly when the content of color conversion materials is increased to enhance durability.
Innovation Solution
A color conversion sheet comprising multiple layers with specific refractive index relationships and haze values, incorporating light scattering particles and distinct light-emitting materials to convert incident light into different wavelengths, ensuring high in-plane uniformity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of color conversion material is increased to improve durability, then durability is improved, but luminance decreases due to aggregation of phosphor
Solution Approach 1:
The color conversion sheet is divided into multiple color conversion layers, each containing different light-emitting materials (green and red phosphors). This segmentation allows independent control of material distribution, preventing aggregation while maintaining sufficient content for durability. Each layer can be optimized separately for both luminance and durability.
Solution Approach 2:
Different regions of the color conversion sheet have different color conversion material contents. The peripheral edge portion has higher content for improved durability, while the central portion maintains lower content for high luminance. This local variation resolves the contradiction between overall durability and overall luminance.
2Reliability
If the content of color conversion material is increased to improve durability, then durability is improved, but in-plane uniformity deteriorates
Solution Approach 1:
By dividing the color conversion function across multiple layers with different materials, the patent achieves uniform distribution of each material type while maintaining high overall content. Each layer provides consistent local conversion, ensuring in-plane uniformity without sacrificing durability.
Solution Approach 2:
The patent uses composite color conversion layers combining multiple light-emitting materials (green and red phosphors) in specific ratios. This composite approach allows precise control over color conversion characteristics and uniformity while maintaining sufficient material content for durability.
3Device complexity
If a single color conversion layer is used to simplify structure, then device complexity is reduced, but color tone variation increases
Solution Approach 1:
The color conversion function is segmented into multiple layers, each handling specific wavelength conversion. This segmentation reduces color tone variation by assigning specific conversion tasks to specific layers, preventing the mixing and aggregation issues that occur in single-layer structures.
Solution Approach 2:
Each color conversion layer uses composite light-emitting materials with specific spectral characteristics. This allows precise control over color tone in each layer, achieving overall color uniformity while maintaining a relatively simple layered 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
The solution achieves both high in-plane uniformity and durability, resulting in improved color reproducibility and luminance with reduced overlap between light emission spectra, enhancing the color gamut and color purity of displays and lighting devices.
Implementation Method 1
a color conversion layer (A), a color conversion layer (B)... the color conversion layer (A) contains a light-emitting material (a) that exhibits light emission with a peak wavelength observed in a region of 500 nm or more and less than 580 nm
Implementation Method 2
either or both of the color conversion layer (A) and the color conversion layer (B) contain light scattering particles
Data Source
AI summary
A color conversion sheet includes at least a color conversion layer, a color conversion layer, a resin layer, and a base layer, the color conversion layer contains a light-emitting material (a) that exhibits light emission with a peak wavelength observed in a region of 500 nm or more and less than 580 nm, the color conversion layer contains a light-emitting material (b) that exhibits light emission with a peak wavelength observed in a region of 580 nm to 750 nm, a haze value of the color conversion sheet is 20% to 90%, and nA1, nA2 and nB satisfy relationships (1) or (2), where nA1 is a refractive index of the color conversion layer, nA2 is a refractive index of the color conversion layer, and nB is a refractive index of the resin layer:nA1>nB and nA2>nB (1)nA1<nB and nA2<nB. (2)