Light Emitting Device with Luminescent Element Cooling
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Solution Overview
Problem
High intensity light emitting devices face challenges in achieving optimum total internal reflection (TIR) and cooling while maintaining a simple, cost-effective structure, as existing solutions often result in complex systems with excessive cooling interfaces and thermal management issues.
Innovation Solution
A light emitting device design featuring a luminescent element with specific surface roughness and flatness, coupled with dual cooling assemblies that provide mechanical and thermal contact through flat interfaces, minimizing thermal interface planes and optimizing both TIR and cooling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If separate cooling elements are used for both the luminescent rod and LEDs, then cooling performance is improved, but device complexity increases due to four cooling interfaces
Solution Approach 1:
The patent combines the cooling functions for the luminescent rod and LEDs into a single integrated cooling element. This cooling element simultaneously contacts both the luminescent rod and the LED board, reducing the number of separate cooling interfaces from four to two, thereby simplifying the overall system structure while maintaining effective thermal management for both components.
2Illumination intensity
If a gap is introduced between the luminescent rod and ambient for optimum TIR, then optical performance is improved, but thermal conductance decreases
Solution Approach 1:
The patent applies different spatial configurations to different functional requirements: an air gap is introduced at the optical interfaces (between luminescent rod and ambient) to enable total internal reflection and improve light extraction, while direct thermal contact is maintained at the thermal interfaces (between luminescent rod and cooling element) to ensure efficient heat removal. This local differentiation of contact quality optimizes both optical and thermal performance simultaneously.
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 design ensures efficient thermal management, keeping the luminescent element below 150°C, while reducing manufacturing complexity and cost by limiting cooling elements to two, thus enhancing both optical and thermal performance.
Implementation Method 1
shorter wavelength light is converted to longer wavelengths in a highly transparent luminescent material
Implementation Method 2
good thermal conductance to a cooling element, typically a heat sink or heat pipe, is required
Implementation Method 3
to obtain optimum total internal reflection (TIR) at the interfaces between the luminescent rod and the ambient
Data Source
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AI summary
A light emitting device (1) comprising a first light source (21) and a second light source (22), a luminescent element (4) comprising a first light input surface (41), a second light input surface (42), a light exit surface (43), a first further surface (44) and a second further surface (45), a first cooling assembly (5) and a second cooling assembly (6), the first cooling assembly (5) comprising a first cooling element (52) and a first light source board (51) on which one of the light sources is mounted, and the second cooling assembly (6) comprising a second cooling element (62) and a second light source board (61), on which the other one of the light sources is mounted, and the second cooling assembly (6) being arranged with a surface (621) in mechanical and thermal contact with the first further surface (44) of the luminescent element thereby forming a first interface and the first cooling assembly (5) being arranged with a surface (521) in mechanical and thermal contact with the second further surface (45) of the luminescent element thereby forming a second interface, the first interface and the second interface comprising a flatness of less than 10 µm, and the root mean squared surface roughness, RRMS, of the first further surface (44) and the second further surface (45) of the luminescent element being comprised in the interval 1 µm < RRMS< 5 µm.