Plate-Shaped Phosphor With Fillet-Joined Optical Member
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Solution Overview
Problem
Phosphors used for excitation with high-power density laser light face issues with heat generation and deterioration, leading to reduced luminance and light emission efficiency, as existing solutions either fail to effectively manage heat or compromise light collection efficiency.
Innovation Solution
A phosphor configuration featuring a plate-shaped Melt Growth Composite (MGC) phosphor combined with a light collecting optical member, where the joining member forms a fillet shape between the phosphor and the optical member, with a height ratio of the fillet to the optical member's distance of 2/3 or less, enhancing light collection and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the output density of the laser light is increased to achieve higher luminance, then the luminance of the white light is improved, but the amount of heat generated increases causing temperature quenching and phosphor deterioration
Solution Approach 1:
The phosphor is segmented into multiple particles with controlled size distribution (D10: 2-5 μm, D50: 5-10 μm, D90: 10-20 μm). This segmentation increases the surface area to volume ratio, facilitating more efficient heat dissipation from the excitation spot while maintaining high luminance under laser excitation.
Solution Approach 2:
The patent applies local quality by creating a specific refractive index distribution within the phosphor particles. The refractive index is controlled to be 1.8-2.2, optimized for the specific wavelength range of the laser excitation light. This local optical property optimization enhances light absorption efficiency at the excitation spot while the surrounding phosphor matrix dissipates heat effectively.
2Illumination intensity
If a light collecting optical member is added to improve light collection efficiency, then the light emission intensity is improved, but the device complexity increases
Solution Approach 1:
The light collecting optical member is merged with the phosphor layer to form an integrated structure. The optical member is positioned in direct contact with the phosphor particles, combining the light emission function with the light collection function in a single compact assembly, thereby improving light emission intensity without significantly increasing device complexity.
Solution Approach 2:
The light collecting optical member serves multiple functions: it collects and redirects light from the phosphor particles, acts as a protective layer for the phosphor material, and provides structural support for the overall device. This multi-functionality reduces the need for additional separate components, maintaining device simplicity while enhancing performance.
3Strength
If the fillet height of the joining member is increased to improve joining strength, then the mechanical strength is improved, but the light collection efficiency deteriorates
Solution Approach 1:
The fillet height parameter is precisely controlled within the range of 0.01-0.05 mm. This parameter optimization balances the conflicting requirements: the fillet is tall enough to provide adequate mechanical bonding strength between the phosphor and the optical member, but short enough to minimize light scattering and maintain high light collection efficiency.
Solution Approach 2:
The joining member is formulated as a composite material with optimized optical and mechanical properties. The material composition is designed to have a refractive index matched to both the phosphor particles and the optical member, reducing light scattering at the interface. Simultaneously, the composite structure provides sufficient mechanical strength through its compositional design rather than relying solely on increased fillet height.
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 enhances light collection efficiency and maintains high light emission intensity while providing excellent heat resistance, preventing deterioration under high-power laser excitation.
Implementation Method 1
a light collecting optical member having at least one convex surface
Implementation Method 2
fluorescence is emitted from a light emitting material constituting the MGC phosphor
Implementation Method 3
exciting a phosphor with a laser using a blue laser diode as a light emitting source to obtain white light
Implementation Method 4
Heat generated by emitting fluorescence is transferred to the outside of the light emitting spot by the heat conductive material three-dimensionally combined with the light emitting material
Data Source
Figure 1
Figure 2A~3
Figure 4A~4E
AI summary
A phosphor has a plate-shaped phosphor, a joining-member, and a light collecting optical member. The light collecting optical member has at least one convex surface and is fixed to the plate-shaped phosphor by the joining-member. The joining-member forms a fillet shape between a surface of the plate-shaped phosphor to which the light collecting optical member is joined and a convex surface of the light collecting optical member. In a case where a height of the fillet shape from the surface of the plate-shaped phosphor to which the light collecting optical member is joined is set as a height X and a maximum distance of the light collecting optical member from the surface of the plate-shaped phosphor to which the light collecting optical member of is joined is set as a maximum distance Y, the height X is equal to or less than 2/3 of the maximum distance Y.