Wavelength Conversion Element with Graded Phosphor Particle Size
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Solution Overview
Problem
Existing light source apparatuses using phosphor-based wavelength conversion struggle to achieve high-intensity fluorescence due to backscattered light and reabsorption of fluorescence, leading to decreased wavelength conversion and fluorescence extraction efficiencies.
Innovation Solution
A wavelength conversion element with a phosphor layer where the minimum particle diameter of phosphor particles on the excitation light incident surface is greater than on the opposite surface, reducing the refractive index interface area and minimizing backscattered and reabsorbed light, combined with a reflective substrate to enhance fluorescence output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a plurality of scatterers are present in the vicinity of the surface on which excitation light is incident, then the excitation light scattering is enhanced, but the wavelength conversion efficiency decreases due to backscattered light and the fluorescence extraction efficiency decreases due to increased reabsorption
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of phosphor particles with different average diameters in different regions. The first region (near excitation light incident surface) has phosphor particles with a larger average diameter, while the second region (near fluorescence extraction surface) has phosphor particles with a smaller average diameter. This local variation in particle size optimizes each region's function: larger particles in the first region reduce backscattering and reabsorption, while smaller particles in the second region enhance fluorescence extraction efficiency.
2Illumination intensity
If a plurality of scatterers are present in the vicinity of the surface on which excitation light is incident, then the excitation light scattering is enhanced, but the fluorescence extraction efficiency decreases due to increased reabsorption
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of phosphor particles with different average diameters in different regions. The first region (near excitation light incident surface) has phosphor particles with a larger average diameter, while the second region (near fluorescence extraction surface) has phosphor particles with a smaller average diameter. This local variation in particle size optimizes each region's function: larger particles in the first region reduce backscattering and reabsorption, while smaller particles in the second region enhance fluorescence extraction efficiency.
3Productivity
If phosphor particles with small diameter are used throughout the phosphor layer, then the fluorescence extraction efficiency is improved, but the wavelength conversion efficiency decreases due to increased backscattered light and reabsorption
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of phosphor particles with different average diameters in different regions. The first region (near excitation light incident surface) has phosphor particles with a larger average diameter, while the second region (near fluorescence extraction surface) has phosphor particles with a smaller average diameter. This local variation in particle size optimizes each region's function: larger particles in the first region reduce backscattering and reabsorption, while smaller particles in the second region enhance fluorescence extraction efficiency.
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 results in a high-intensity fluorescence output by reducing backscattered and reabsorbed light, thereby improving wavelength conversion and fluorescence extraction efficiencies, and simplifying the manufacturing process by eliminating the need for a separate reflection layer.
Implementation Method 1
a plurality of phosphor particles that convert the excitation light in terms of wavelength to produce fluorescence
Implementation Method 2
the surface of each of the phosphor particles surrounded by the binder, that is, the surface where each of the phosphor particles is in contact with the binder is the refractive index interface... The amount of backscattered excitation light in the vicinity of the first surface on which the excitation light is incident is reduced
Data Source
AI summary
A wavelength conversion element includes a wavelength conversion layer having a first surface on which excitation light is incident, a second surface located on the side opposite the first surface, a plurality of phosphor particles that convert the excitation light in terms of wavelength to produce fluorescence, and a binder that holds the plurality of phosphor particles. The plurality of phosphor particles have a particle diameter distribution, and the minimum particle diameter in the particle diameter distribution of a plurality of the phosphor particles contained in a first region located on the side facing the first surface is greater than the minimum particle diameter in the particle diameter distribution of a plurality of the phosphor particles contained in a second region located on the side facing the second surface.