Segmented Ceramic Phosphor Array for Heat-Stable Light Conversion
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Solution Overview
Problem
High-power density in light sources using ceramic phosphors leads to heat management issues, including crack formation and delamination due to non-uniform optical load, which affects the reliability of the luminescent element in reflective mode.
Innovation Solution
A luminescent element comprising a plurality of element bodies with different thermal conductivities, where some bodies are non-luminescent and light transmissive, arranged in a 2D configuration to enhance thermal dissipation and optical efficiency, and attached to a thermally conductive support for improved heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic phosphor is coated with a highly reflective layer and soldered to a heat sink to improve heat management and adhesion, then thermal management and reliability are improved, but under high optical load the phosphor may still experience crack formation and delamination
Solution Approach 1:
The phosphor is divided into multiple small ceramic phosphor particles instead of using a single large phosphor block. This segmentation reduces thermal stress concentration and prevents crack propagation across the entire phosphor area, while each particle maintains good thermal contact with the heat sink through the reflective layer
Solution Approach 2:
The reflective layer is applied selectively to the bottom surface of each ceramic phosphor particle that contacts the heat sink, providing localized thermal management where it is most needed, while the top and side surfaces maintain their phosphor properties for light conversion
2Device complexity
If a single ceramic phosphor is used to convert light, then the structure is simple, but heat management becomes difficult under high power density leading to reliability issues
Solution Approach 1:
The single phosphor structure is segmented into multiple small ceramic phosphor particles dispersed on the heat sink surface. This increases the total surface area for heat dissipation while maintaining simple overall device structure, and each particle independently manages its own thermal load
Solution Approach 2:
The phosphor is transitioned from a volumetric block to a planar distribution of particles on the heat sink surface. This two-dimensional arrangement increases thermal contact area with the heat sink while simplifying the overall device architecture
3Illumination intensity
If high optical load is applied to achieve high brightness, then light output is improved, but crack formation and delamination occur reducing reliability
Solution Approach 1:
The phosphor is segmented into multiple small particles that can independently handle optical load. Cracks that form under high brightness conditions are contained within individual particles and do not propagate across the entire phosphor area, maintaining overall reliability
Solution Approach 2:
The optical load is distributed across multiple phosphor particles rather than concentrated on a single phosphor. This changes the stress distribution parameters and allows the system to handle higher total optical load while maintaining individual particle integrity
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 effectively dissipates heat, reduces the risk of crack formation and delamination, and improves color mixing by enhancing thermal management and light distribution within the luminescent element.
Implementation Method 1
the luminescent material is configured to convert at least part of first radiation, selected from one or more of UV radiation and visible radiation, into luminescent material light
Implementation Method 2
the plurality of element bodies are configured in thermal contact with the thermally conductive support
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~1F
AI summary
The invention provides a light generating device (1000) comprising a light source (10) and a luminescent element (20), wherein: - the light source (10) is configured to generate the first radiation (11); wherein the light source (10) comprises a laser light source; - the luminescent element (20) comprises (i) a plurality of element bodies (200) and (ii) a thermally conductive support (400); wherein the plurality of element bodies (200) comprises a plurality of first bodies (210) and a plurality of second bodies (220); - the plurality of first bodies (210) comprise a luminescent material (50), wherein the luminescent material (50) is configured to convert at least part of first radiation (11), selected from one or more of UV radiation and visible radiation, into luminescent material light (51); wherein the first bodies have a first thermal conductivity K1; wherein the first bodies (210) are configured in a light receiving relationship with the light source (10); - the plurality of second bodies (220), different from the first bodies (210) are light transmissive for one or more wavelengths of the first radiation (11) and the luminescent material light (51); wherein the second bodies (220) have a second thermal conductivity K2, wherein K2≥0.2*K1; - the plurality of first bodies (210) and the plurality of second bodies (220) are configured in a 2D arrangement (205), wherein for a plurality of second bodies (220) applies that they are configured adjacent to different first bodies (210); and - the plurality of first bodies (210) and second bodies (220) are configured in thermal contact with the thermally conductive support (400).