Phosphor Distribution in Light-Emitting Packages to Reduce Leakage Light
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Solution Overview
Problem
Existing light-emitting devices with phosphors in covering members suffer from suboptimal light emission characteristics due to inefficient phosphor distribution and content.
Innovation Solution
A light-emitting device design featuring a light-emitting element, a wavelength conversion member, and a covering member with a specific distribution of phosphors, where the content of phosphor particles above the light-emitting element's surface is less than below, utilizing a light-reflective material and phosphors that emit light with peak wavelengths longer than the initial light, enhancing light extraction efficiency and chromaticity adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If phosphor is uniformly distributed in the covering member, then the manufacturing process is simple, but the light emission characteristics are suboptimal due to inefficient phosphor distribution
Solution Approach 1:
The patent applies local quality by creating non-uniform phosphor distribution in the covering member. Specifically, the phosphor concentration varies at different positions: higher concentration near the light-emitting element where excitation is strongest, and lower concentration toward the outer regions. This localized variation optimizes light emission characteristics by matching phosphor distribution to the excitation light intensity profile, thereby improving conversion efficiency while maintaining manufacturing feasibility through controlled mixing processes.
2Power
If phosphor content is increased to enhance light conversion, then luminous flux improves, but leakage light increases and chromaticity control becomes difficult
Solution Approach 1:
The patent applies parameter changes by optimizing the phosphor content parameter within a specific range (5-20 wt%) rather than using excessive amounts. Additionally, the particle size parameter is controlled (3-10 μm) to balance conversion efficiency and leakage reduction. The non-uniform spatial distribution of phosphor further modulates the effective phosphor content at different locations, achieving high luminous flux while minimizing leakage light through parameter optimization rather than simple quantity increase.
Solution Approach 2:
The patent uses composite materials by combining phosphor particles with a transparent resin matrix to form the covering member. This composite structure allows precise control of phosphor concentration and distribution within the resin, enabling optimization of light conversion while maintaining transparency to prevent leakage. The composite material approach also facilitates chromaticity control by selecting specific phosphor types and ratios within the composite.
3Illumination intensity
If phosphor content is increased to improve light conversion, then more light is emitted, but the appearance and chromaticity of the device are adversely affected
Solution Approach 1:
The patent applies parameter changes by controlling phosphor content within 5-20 wt% and particle size within 3-10 μm to balance emission intensity and appearance. The non-uniform spatial distribution parameter further optimizes this balance by concentrating phosphor where it most effectively converts light while minimizing visible impact on overall appearance. This parameter control ensures high illumination intensity without compromising chromaticity uniformity or device aesthetics.
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 desired chromaticity and appearance.
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
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.