Wavelength Conversion Member with Concave Resin Layer for Thin Backlight Units
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Solution Overview
Problem
Thin wavelength conversion layers in flat panel displays, such as LCDs, result in reduced phosphor content, leading to lower luminescence and color reproducibility due to in-plane thickness unevenness, causing color unevenness and decreased color reproducibility.
Innovation Solution
A wavelength conversion member with a resin layer having concave portions and fluorescent regions containing phosphors, where the surface roughness of the resin layer is between 0.3 to 5 μm, and a refractive index difference between the resin layer and fluorescent regions is 0.05 or more, to enhance light scattering and maintain high color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the wavelength conversion layer is made thin to reduce display device thickness, then the overall device can be thinner, but the phosphor content is reduced leading to lower luminescence and color reproducibility
Solution Approach 1:
The patent applies local quality by creating concave portions at specific locations within the wavelength conversion layer where phosphor is concentrated. This localized phosphor arrangement in the concave portions ensures sufficient luminescence intensity even when the overall layer thickness is reduced, resolving the contradiction between thinning the layer and maintaining luminescence.
Solution Approach 2:
The patent changes the physical parameters of the wavelength conversion layer by controlling the depth and dimensions of the concave portions. By adjusting these geometric parameters, the patent optimizes phosphor distribution to maintain color reproducibility and luminescence intensity while keeping the overall layer thin.
2Length of moving object
If the wavelength conversion layer is made thin, then the device can be thinner, but in-plane thickness unevenness increases causing color unevenness and reduced color reproducibility
Solution Approach 1:
The concave portions create localized regions of enhanced phosphor concentration that compensate for in-plane thickness variations. This local quality enhancement ensures uniform color reproduction across the display surface even when the wavelength conversion layer is made thin.
3Ease of manufacture
If quantum dots are dispersed in resin to create a wavelength conversion member, then the structure is simplified and ease of manufacture is improved, but the phosphor content is reduced when the layer is thinned leading to lower luminescence
Solution Approach 1:
The patent maintains the simple dispersed structure for ease of manufacture but introduces concave portions that locally concentrate phosphor. This combination preserves manufacturing simplicity while ensuring sufficient fluorescence intensity through localized phosphor enhancement.
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 configuration increases the light quantity of fluorescence emitted, suppressing color reproducibility issues caused by thickness variations and maintaining high color accuracy even when the wavelength conversion layer is thin.
Implementation Method 1
a refractive index difference Δn between the resin layer and the fluorescent region is 0.05 or more, to enhance light scattering
Implementation Method 2
a wavelength conversion member including a phosphor that emits fluorescence upon irradiation with excitation light
Implementation Method 3
absorbs at least a part of incident excitation light, converts the absorbed light into light having a wavelength different from the wavelength of the excitation light
Data Source
AI summary
Provided are a wavelength conversion member which contains a phosphor such as a quantum dot and has high reproducibility of white light; and a backlight unit. The wavelength conversion member includes a wavelength conversion layer having a resin layer that is provided with a plurality of concave portions which are discretely disposed on one main surface thereof; and a plurality of fluorescent regions containing phosphors, which are disposed in the concave portions formed in the resin layer, in which a surface roughness Ra of a surface of the resin layer on a side where the concave portions are formed is 0.3 to 5 μm.