Wavelength Conversion Particle Distribution for LED Color Uniformity
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Solution Overview
Problem
Light emitting devices used as backlights or lighting apparatuses face issues with color non-uniformity across different light distribution angles, which existing technologies have not adequately addressed.
Innovation Solution
A light emitting device design incorporating a light emitting element, a light guide member, a first wavelength conversion member with specific particle size and weight ratios, and a reflective member to enhance light diffusion and extraction, reducing color non-uniformity and improving light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional light emitting device structure is used, then the device can provide basic lighting function, but color non-uniformity occurs across different light distribution angles
Solution Approach 1:
The patent optimizes specific parameters of the wavelength conversion layer including thickness (50-150 μm), particle size distribution (D50: 5-15 μm, D90: 20-30 μm), and particle content (5-20 wt%). By precisely controlling these parameters, the device achieves uniform color distribution across different viewing angles without requiring complex multi-layer structures or additional optical components.
Solution Approach 2:
The patent applies wavelength conversion particles with specific size distribution and concentration gradients within the wavelength conversion layer to achieve uniform color output. The controlled particle size distribution (with D90/D50 ratio between 1.3-3.0) creates optimal light scattering and wavelength conversion throughout the layer, ensuring consistent color properties in different directions while maintaining a relatively simple overall device structure.
2Use of energy by moving object
If wavelength conversion particles with small particle size are used, then light extraction efficiency improves, but color non-uniformity increases
Solution Approach 1:
The patent identifies and optimizes the critical parameter of particle size distribution, specifically setting D50 between 5-15 μm and D90 between 20-30 μm with a D90/D50 ratio of 1.3-3.0. This controlled distribution ensures sufficient light scattering for high extraction efficiency while maintaining uniform color distribution across viewing angles, resolving the trade-off between efficiency and uniformity.
Solution Approach 2:
The wavelength conversion layer functions as a composite material system combining resin matrix with specifically distributed wavelength conversion particles. The controlled particle size distribution creates a composite structure that optimizes both light scattering (for extraction efficiency) and wavelength conversion uniformity (for color consistency), achieving dual benefits simultaneously.
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 proposed design effectively reduces color non-uniformity and enhances light extraction efficiency by optimizing the particle size and weight ratio of wavelength conversion particles and the structure of the light emitting device, resulting in improved light distribution and color rendering properties.
Implementation Method 1
a first wavelength conversion member covering the first surface, the first wavelength conversion member including a first matrix and first wavelength conversion particles
Implementation Method 2
a reflective member covering the lateral surface of the light emitting element, a lateral surface of the light guide member and a lateral surface of the first wavelength conversion member
Implementation Method 3
a light guide member covering at least a part of a lateral surface of the light emitting element
Data Source
AI summary
A light emitting device includes a light emitting element including a first surface; a light guide member covering at least a part of a lateral surface of the light emitting element; a first wavelength conversion member covering the first surface and including a first wavelength conversion particles; and a reflective member being in contact with the light emitting element. The first wavelength conversion member has a thickness of 60 μm or more and 120 μm or less. The first wavelength conversion particles have an average particle size of 4 μm or longer and 12 μm or smaller; the first wavelength conversion particles have a central particle size of 4 μm or longer and 12 μm or smaller. A weight ratio of the first wavelength conversion particles is 60% by weight or more and 75% by weight or less with respect to the total weight of the first wavelength conversion member.