Wavelength Conversion Device Thermal Management via Dual Reflection Layers
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Solution Overview
Problem
Current wavelength conversion devices in projection systems face challenges with heat dissipation and reflectivity, as the existing reflective layers are costly, prone to separation, and have limited temperature resistance, while diffuse reflection particles suffer from low thermal conductivity, leading to reduced luminous efficiency.
Innovation Solution
A wavelength conversion device is designed with a heat dissipation substrate, a first reflection layer with high thermal conductivity, and a second reflection layer with high reflectivity but low thermal conductivity, stacked sequentially to enhance heat dissipation and maintain reflectivity, improving the brightness of the illumination system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single reflection layer with high reflectivity (such as titanium dioxide, silicon dioxide, aluminum oxide, zirconium oxide, or barium sulfate) is used, then the reflectivity is high (greater than or equal to 95%), but the thermal conductivity is low (less than 10 W/mK), causing excess temperature and reduced luminous efficiency
Solution Approach 1:
The reflection layer is divided into two separate layers: a first reflection layer with high thermal conductivity (boron nitride, thermal conductivity greater than 20 W/mK) and a second reflection layer with high reflectivity (titanium dioxide, silicon dioxide, aluminum oxide, zirconium oxide, or barium sulfate). This segmentation allows each layer to independently optimize its function without compromising the other.
Solution Approach 2:
The patent uses a composite structure combining two different reflective materials with complementary properties. The first layer uses boron nitride for thermal management, while the second layer uses high-reflection materials for optical performance. This composite approach resolves the contradiction between thermal conductivity and reflectivity.
2Temperature
If the first reflection layer (high thermal conductivity) is made thinner than the second reflection layer (high reflectivity), then the reflectivity is maintained, but the heat dissipation effect is reduced
Solution Approach 1:
The patent optimizes the thickness parameters of both layers: the first reflection layer has a thickness of 5-20 μm and the second reflection layer has a thickness of 1-10 μm. These specific parameter ranges ensure that the thicker first layer provides sufficient heat dissipation while the thinner second layer maintains high reflectivity.
3Illumination intensity
If a specular reflection layer (silver or aluminum coating) is used, then the reflectivity is high, but the coating is prone to separation and has limited temperature resistance (destroyed when temperature exceeds 300°C)
Solution Approach 1:
The patent replaces the expensive and unreliable metallic specular reflection layer with a diffuse reflection layer made of ceramic particles (boron nitride, titanium dioxide, silicon dioxide, aluminum oxide, zirconium oxide, or barium sulfate). These materials are more stable at high temperatures and resistant to separation, sacrificing some cost for significantly improved reliability.
Solution Approach 2:
The patent uses a composite diffuse reflection structure combining boron nitride (for thermal conductivity and stability) with other ceramic particles (for reflectivity). This composite material approach provides both high temperature resistance and high reflectivity without the separation issues of metallic coatings.
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 significantly enhances heat dissipation and maintains good reflectivity, resulting in improved brightness and efficiency of the projection device by optimizing the thermal management and reflectivity of the wavelength conversion device.
Implementation Method 1
a first reflection layer with high thermal conductivity
Implementation Method 2
A reflectivity of the second reflection layer to a visible light is greater than a reflectivity of the first reflection layer to the visible light
Implementation Method 3
a second reflection layer with high reflectivity but low thermal conductivity
Implementation Method 4
emitting a blue excitation beam to a phosphor color wheel using a blue laser diode, and exciting a phosphor of the phosphor color wheel using the excitation beam to generate a yellow-green light
Data Source
AI summary
A wavelength conversion device includes a heat dissipation substrate, a first reflection layer, a second reflection layer, and a wavelength conversion layer. The first reflection layer is disposed on the heat dissipation substrate. The second reflection layer is disposed on the first reflection layer. The wavelength conversion layer is disposed on the second reflection layer. The first reflection layer is located between the heat dissipation substrate and the second reflection layer, and the second reflection layer is located between the first reflection layer and the wavelength conversion layer. A reflectivity of the second reflection layer to a visible light is greater than a reflectivity of the first reflection layer to the visible light, and a thickness of the first reflection layer is greater than or equal to a thickness of the second reflection layer. A projection device having the wavelength conversion device is further provided.