Ceramic Phosphor Void Control for Thermal and Optical Balance
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Solution Overview
Problem
Existing phosphors with voids suffer from low thermal conductivity, luminous efficiency deterioration, and thermal stress, making them unsuitable for high-intensity laser applications, and also face challenges in forming optical functional layers due to surface concave portions.
Innovation Solution
A phosphor composed of a sintered ceramic material with Ce:Y3Al5O12 as the main phase and a ceramic subphase with different refractive index, incorporating crystal grain boundaries and voids, which acts as a light scattering source, enhancing thermal conductivity and light scattering properties while reducing voids and surface defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If voids are included in the phosphor to scatter fluorescence, then light scattering function is improved, but thermal conductivity is reduced and heat accumulates
Solution Approach 1:
The patent utilizes the porous structure (voids) in the phosphor material to scatter fluorescence effectively. The voids act as scattering centers that increase the extraction efficiency of fluorescence generated inside the phosphor, while the patent manages the thermal conductivity issue through careful control of void distribution and size.
Solution Approach 2:
The patent optimizes parameters such as void size, void distribution, and void concentration to achieve the right balance between light scattering function and thermal conductivity. By controlling these parameters, the phosphor can effectively scatter fluorescence while maintaining sufficient heat dissipation capability.
2Illumination intensity
If high-intensity laser light is used to excite the phosphor, then luminous intensity is improved, but thermal stress increases and may break the phosphor
Solution Approach 1:
The patent optimizes the physical and chemical parameters of the phosphor material, including composition ratios, particle size distribution, and sintering conditions, to enhance thermal stress resistance while maintaining high luminous intensity under laser excitation.
Solution Approach 2:
The patent employs composite phosphor structures combining different materials or phases that have complementary properties - one component provides high luminous efficiency under laser excitation while another component enhances thermal stress resistance and heat dissipation.
3Reliability
If voids are reduced to improve thermal conductivity, then heat dissipation is improved, but light scattering function is reduced
Solution Approach 1:
The patent carefully controls void parameters (size, distribution, concentration) to achieve optimal balance between thermal conductivity and light scattering function.
Solution Approach 2:
The patent creates non-uniform void distribution within the phosphor structure, with different void characteristics in different regions to simultaneously satisfy light scattering requirements and thermal conductivity requirements in different zones.
4Shape
If the phosphor is processed into a phosphor layer by polishing, then surface flatness is improved, but voids are exposed creating concave portions
Solution Approach 1:
The patent performs preliminary treatments during the sintering or processing stage to pre-position or seal voids before the polishing step, preventing them from being exposed as concave portions on the final surface.
Solution Approach 2:
The patent optimizes polishing parameters and employs multi-stage polishing processes to remove surface irregularities while preserving the underlying void structure, or uses chemical-mechanical polishing to achieve flat surfaces without exposing internal voids.
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 achieves a balance between thermal conductivity and light scattering, improving quantum yield and preventing damage from heat, allowing for high-luminance and reliable operation in light source devices and projectors.
Implementation Method 1
The ceramic material has a refractive index different from that of the main phase. The sintered body further includes a crystal grain boundary and a void at the crystal grain boundary... the subphase favorably functions as a light scattering source. Specifically, a boundary between the main phase and the subphase functions as a light scattering source.
Implementation Method 2
JP-A-2009-277516 describes a light source device utilizing fluorescence emitted from a phosphor as illumination light... an inorganic phosphor which does not contain an organic material
Implementation Method 3
the thermal conductivity of the phosphor is lower than the thermal conductivity of the phosphor particles. Due to this, when the phosphor is irradiated with high-intensity laser light as excitation light, heat is accumulated therein
Data Source
AI summary
A phosphor includes a sintered body of a ceramic material. The sintered body contains Ce:Y3Al5O12 as a main phase and a ceramic material as a subphase. The ceramic material has a refractive index different from that of the main phase. The sintered body has a crystal grain boundary and a void at the crystal grain boundary.