Light Emitting Apparatus Refractive Index Gradient
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Solution Overview
Problem
Current light emitting apparatuses face challenges in generating warm white light with high color rendering index (CRI) and efficient light extraction, often resulting in reduced light efficiency due to refractive index differences between light sources and medium layers.
Innovation Solution
A light emitting apparatus comprising a sub-mount with first and second light sources emitting in different wavelength bands, a wavelength conversion layer, and a medium layer with distinct refractive indices, along with a diffusion layer and transparent layers to scatter and disperse light, ensuring reliable fixation and improved light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light sources with different wavelength bands are used to generate warm white light, then the color rendering index (CRI) is improved, but the light extraction efficiency is reduced due to refractive index differences
Solution Approach 1:
A transparent layer with refractive index n2 is introduced as an intermediary between the light sources (refractive index n1) and the medium layer (refractive index n3). This intermediate layer reduces the refractive index difference at interfaces, minimizing total internal reflection and improving light extraction efficiency while allowing multiple wavelength bands to pass through for high CRI warm white generation
Solution Approach 2:
The refractive index parameter is strategically varied across different layers (n1 for light sources, n2 for transparent layer, n3 for medium layer) to optimize light extraction. By creating a gradient of refractive indices, the patent reduces abrupt changes that cause total internal reflection, thereby improving light extraction efficiency for multi-wavelength light sources
2Loss of energy
If a diffusion layer is added to scatter and disperse light, then light extraction efficiency is improved, but the device complexity increases
Solution Approach 1:
The diffusion layer is integrated with the transparent layer, combining the functions of light scattering/diffusion and optical transmission in a single component. This merging approach improves light extraction efficiency through diffusion while avoiding the complexity of separate diffusion and transparent layers
Solution Approach 2:
The diffusion layer is positioned specifically between the light sources and the medium layer, where it is most needed for scattering light that would otherwise be trapped by total internal reflection. This localized application of diffusion functionality optimizes light extraction without adding complexity throughout the entire device structure
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 apparatus effectively generates warm white light with a high CRI and improved light extraction efficiency by attenuating refractive index differences and minimizing light loss, enhancing the overall light efficiency and reliability.
Implementation Method 1
a wavelength conversion layer on the first transparent layer to convert at least one of the light having the first main wavelength band and the light having the second main wavelength band into a light having a third main wavelength band
Implementation Method 2
the diffusion layer is adapted to scatter, disperse or reflect light which is generated from the first and second light sources
Data Source
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AI summary
A light emitting apparatus includes a first light source to generate light having a first main wavelength band, a second light source to generate light having a second main wavelength band, a first transparent layer surrounding the first and second light sources, a wavelength conversion layer disposed on the first transparent layer to convert at least one of the light having the first main wavelength band and the light having the second main wavelength band into light having a third main wavelength band, and a medium layer between the wavelength conversion layer and the first transparent layer. At least of the first or second light sources has a first refractive index, the first transparent layer has a second refractive index, the medium layer has a third refractive index, the wavelength conversion layer has a fourth refractive index, and the first to fourth refractive indexes are different from each other.