Depth-Graded Phosphor Layout in Light-Emitting Packages
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Solution Overview
Problem
Existing light-emitting devices have limitations in the containment of phosphors within the covering member, which affects the light emission characteristics.
Innovation Solution
A light-emitting device configuration where a phosphor is strategically distributed with a higher content below the upper surface of the light-emitting element and a lower content above, utilizing a covering member containing light-reflective materials and phosphors that emit light with a peak wavelength longer than the second light, enhancing light extraction efficiency and chromaticity adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphor content is increased above the upper surface to enhance light emission, then luminous flux is improved, but visible phosphor content increases affecting appearance
Solution Approach 1:
The patent applies local quality by creating a non-uniform phosphor distribution where the content varies with depth. Specifically, the phosphor content is higher below the upper surface and lower above it, optimizing light emission from the functional region while minimizing visible phosphor in the appearance region. This gradient distribution allows different regions to serve different purposes: the lower region for light generation and the upper region for aesthetic appearance.
2Ease of manufacture
If phosphor is contained uniformly in the covering member, then manufacturing is simplified, but light emission characteristics are suboptimal
Solution Approach 1:
The patent implements local quality through a depth-dependent phosphor distribution strategy. The covering member contains phosphor with varying concentration at different depths: higher concentration below the upper surface for optimal light emission, and lower concentration above for appearance quality. This can be achieved through manufacturing techniques like gradient mixing or layered deposition, balancing manufacturing feasibility with performance optimization.
3Illumination intensity
If phosphor content is increased to improve luminous flux, then light emission is enhanced, but leakage light increases at higher temperatures
Solution Approach 1:
The patent addresses temperature-dependent leakage light by implementing local quality in phosphor distribution. By concentrating phosphor content in the lower region below the upper surface and reducing it in the upper region, the patent optimizes light extraction where it is most effective while minimizing regions where thermal leakage can occur. The lighter upper region reduces phosphor-related thermal effects and leakage light generation at elevated temperatures.
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
Improves light emission characteristics by reducing leakage light and enhancing luminous flux, particularly at higher temperatures, while maintaining a desirable appearance by minimizing visible phosphor content above the light-emitting surface.
Implementation Method 1
a wavelength conversion member disposed on an upper surface of the light-emitting element and configured to emit, by excitation by the first light, a second light having a peak wavelength longer than a peak wavelength of the first light
Implementation Method 2
The phosphor is configured to emit, by excitation by the first light, a third light having a peak wavelength longer than the peak wavelength of the second light
Implementation Method 3
a covering member disposed around the light-emitting element and the wavelength conversion member in a top view and containing a light-reflective material and a phosphor
Data Source
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Figure 3
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AI summary
A light-emitting device includes a light-emitting element configured to emit a first light, a wavelength conversion member disposed on an upper surface of the light-emitting element and configured to emit, by excitation by the first light, a second light having a peak wavelength longer than a peak wavelength of the first light, and a covering member disposed around the light-emitting element and the wavelength conversion member and containing a light-reflective material and a phosphor. The phosphor is configured to emit, by excitation by the first light, a third light having a peak wavelength longer than the peak wavelength of the second light. The content of the phosphor above the upper surface of the light-emitting element is less than the content of the phosphor below the upper surface of the light-emitting element.