Wavelength Conversion Microparticles for High Purity Displays
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Solution Overview
Problem
Existing wavelength conversion members for liquid crystal display devices face challenges in achieving both high color purity and durability, particularly due to degradation from heat, moisture, and oxygen, and require complex processes for maintaining high color purity when using multiple organic light emitting materials in different layers.
Innovation Solution
A wavelength conversion member comprising a substrate with a wavelength conversion layer containing a binder and microparticles, where the microparticles include a pyrromethene derivative and a matrix, with an oxygen permeability coefficient of 0.01 (cc·mm)/(m2·day·atm) or less, and an emulsifier content of 0.01% to 5% by mass, allowing for the use of microparticles with an average diameter of 1 μm to 15 μm, and either separate layers or a laminate configuration for improved durability and ease of production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If quantum dots or organic light emitting materials are used to narrow emission spectra for improved color reproducibility, then color purity is improved, but durability against heat, moisture, and oxygen deteriorates
Solution Approach 1:
The patent uses composite materials by combining organic light emitting materials with inorganic matrix materials (such as silica) to form microparticles. This composite structure allows the organic material to provide narrow emission spectra for high color purity while the inorganic matrix provides protection against heat, moisture, and oxygen degradation, thereby improving durability. The microparticles consist of an inorganic matrix containing the organic light emitting material dispersed within it, creating a synergistic combination that resolves the contradiction between color purity and durability.
Solution Approach 2:
The patent employs thin film encapsulation by forming an inorganic matrix layer (such as silica) around the organic light emitting material to create a protective barrier. This thin film structure physically isolates the organic material from harmful environmental factors including oxygen, moisture, and heat, preventing degradation while maintaining the material's optical properties for high color purity emission.
2Manufacturing precision
If pyrromethene derivatives are used as organic light emitting materials, then color purity is improved, but degradation from singlet oxygen and radicals deteriorates
Solution Approach 1:
The patent creates an inert environment by enclosing the pyrromethene derivative within an inorganic matrix (such as silica) that acts as a barrier to oxygen and other reactive species. This inert encapsulation prevents singlet oxygen and radicals from reaching and degrading the organic light emitting material, while still allowing the material to emit light with high color purity. The matrix effectively isolates the sensitive organic material from harmful atmospheric components.
Solution Approach 2:
The patent applies beforehand cushioning by pre-encapsulating the pyrromethene derivative in an inorganic matrix before exposure to harmful environmental conditions. This protective structure is formed in advance to prevent degradation from singlet oxygen and radicals, acting as a preventive measure that cushions the organic material against future degradation while maintaining its optical emission properties.
3Ease of manufacture
If multiple organic light emitting materials are placed in the same layer, then production is simplified, but color purity deteriorates due to mixing at interfaces
Solution Approach 1:
The patent applies segmentation by dividing the wavelength conversion layer into multiple separate layers, with each layer containing a specific organic light emitting material encapsulated in microparticles. This segmentation prevents mixing between different organic materials that would occur in a single layer, thereby maintaining high color purity for each emission wavelength. Each layer can be independently controlled and optimized for its specific function.
Solution Approach 2:
The patent transitions from a two-dimensional mixed composition to a three-dimensional layered structure. By stacking multiple layers vertically (adding the vertical dimension), the patent prevents lateral mixing between different organic light emitting materials while maintaining production efficiency. Each layer remains distinct and separated, preserving color purity, yet the overall structure can be formed through continuous coating processes.
4Manufacturing precision
If separate layers are produced and bonded to maintain color purity, then color purity is improved, but production process complexity increases
Solution Approach 1:
The patent merges the functions of multiple separate production steps into a single continuous coating process. Different wavelength conversion layers containing different organic light emitting materials are deposited sequentially in one continuous operation, eliminating the need for separate production and bonding steps. This integration maintains color purity through physical separation of layers while simplifying the overall production process.
Solution Approach 2:
The patent applies preliminary action by preparing each wavelength conversion layer with appropriate adhesion promoters and surface treatments in advance during the coating process. This preliminary preparation ensures that layers bond well to each other during sequential deposition, maintaining structural integrity and color purity without requiring complex post-production bonding operations.
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 enables both high color purity and durability of the wavelength conversion member, simplifying the production process and preventing degradation from oxygen, while maintaining high brightness and color accuracy in liquid crystal display devices.
Implementation Method 1
microparticles 34G containing a pyrromethene derivative exhibiting light emission by using excitation light, in which a peak wavelength is observed in a region of 500 nm or more and 580 nm or less
Data Source
AI summary
Provided is a wavelength conversion member including a wavelength conversion layer and a substrate, in which the wavelength conversion layer contains a binder and microparticles, and the microparticles contain a pyrromethene derivative and a matrix.