Moth-Eye Wavelength Conversion Particle Antireflection
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Solution Overview
Problem
Existing wavelength conversion members in light emitting devices face inefficiencies in incident light absorption and conversion light extraction due to Fresnel reflection and total reflection, which limit the overall light output and durability of the devices.
Innovation Solution
The introduction of a wavelength conversion particle with a moth-eye structure and a translucent metal-oxide layer, where the moth-eye structure on the fluorescent particle surface reduces Fresnel reflection and the metal-oxide layer enhances moisture resistance, allowing for improved absorption and extraction of light, and the use of a translucent medium with a refraction index matching the metal-oxide layer for antireflection effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a translucent coated layer is formed on the fluorescent particle to improve light incident efficiency, then the incident efficiency of exciting light is improved, but Fresnel reflection and total reflection still occur at the interfaces, limiting further efficiency improvement
Solution Approach 1:
The patent applies a moth-eye structure with fine concavo-convex patterns on the fluorescent particle surface. This curved, non-planar surface structure reduces Fresnel reflection by creating a gradual transition in refractive index, allowing light to pass through more efficiently without the sharp interfaces that cause reflection in conventional coated structures.
Solution Approach 2:
The moth-eye structure creates a porous-like fine concavo-convex surface topology on the fluorescent particle. This structured surface acts as an antireflection layer, enabling gradual light penetration and reducing reflection losses at the particle surface, thereby improving both incident efficiency of exciting light and extraction efficiency of conversion light.
2Productivity
If the refraction index of the translucent coated layer is set between the fluorescent particle and translucent medium to improve light extraction, then extraction efficiency is improved, but moisture resistance and durability are compromised
Solution Approach 1:
The patent removes the translucent coated layer entirely and replaces it with a moth-eye structure formed directly on the fluorescent particle surface. This eliminates the need for intermediate materials with specific refraction indexes, simplifying the structure while maintaining optical efficiency through the geometric moth-eye pattern rather than material composition.
Solution Approach 2:
The patent creates a composite structure by forming the moth-eye pattern directly on the fluorescent particle surface, integrating the antireflection function into the particle itself rather than using separate coating layers. This integrated approach improves both optical performance and environmental durability.
3Illumination intensity
If conventional wavelength conversion members are used, then the device can operate, but the overall light output is limited due to reflection losses and the device lifespan is reduced due to moisture degradation
Solution Approach 1:
The moth-eye structure with its fine concavo-convex curved surface patterns reduces reflection losses at the fluorescent particle surface, improving both light incident efficiency and extraction efficiency. This increases overall light output while the integrated structure enhances durability against moisture degradation, extending device lifespan.
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 significantly enhances the incident efficiency of exciting light and the extraction efficiency of conversion light, leading to higher light output and improved moisture resistance, thus extending the device's operational lifespan and performance.
Implementation Method 1
Fresnel reflection occurs at an interface between translucent medium 173 and translucent coated layer 172, and at an interface between translucent coated layer 172 and fluorescent particle 171
Implementation Method 2
a wavelength conversion particle formed by using a fluorescent particle... the fluorescent particle(s) emits light excited by light emitted from the LED chip and thereby having a color different from the light emitted from the LED chip
Implementation Method 3
the use of a translucent medium with a refraction index matching the metal-oxide layer for antireflection effects
Implementation Method 4
the metal-oxide layer enhances moisture resistance, allowing for improved absorption and extraction of light, and the use of a translucent medium with a refraction index matching the metal-oxide layer for antireflection effects
Data Source
Figure 1A~1D
Figure 2
Figure 3A~3C
AI summary
A wavelength conversion particle 7 used for a wavelength conversion member 70 is provided with a moth-eye structure section 74 having a fine concavo-convex structure in the side of a surface of a fluorescent particle 71, and the fine concavo-convex structure is formed in fluorescent particle 71 itself. Wavelength conversion member 70 is formed by dispersing wavelength conversion particle(s) 7 into a translucent medium 73 having a smaller refraction index than fluorescent particle 71 of wavelength conversion particle 7. Wavelength conversion member 70 is further provided with an antireflection section 76 in the side of the surface of fluorescent particle 71. Antireflection section 76 comprises moth-eye structure section 74 and translucent medium 73 entered between taper-shaped fine projections 75 of moth-eye structure section 74. In a light emitting device 1, wavelength conversion member 70 is used as a color conversion member converting a part of light emitted from a LED chip 10 into light having a longer wavelength than the light emitted from LED chip 10 and emitting the converted light.