LED Light-Emitting Device with Segmented Phosphor Layers
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Solution Overview
Problem
Light-emitting devices face issues with heat dissipation and color unevenness due to phosphor deposition in the sealing resin, leading to reduced lifespan and efficiency, as well as manufacturing variability when trying to achieve an intermediate state between dispersion and deposition.
Innovation Solution
A light-emitting device design featuring a mount board with an LED element and a translucent sealing resin containing first and second particulate phosphors with different specific gravities, where the first phosphor is dispersed in a layer covering areas beside and above the LED element, and the second phosphor is deposited on the mount board and LED element surfaces, aided by nanoscale fillers to prevent sinking and ensure consistent deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the phosphor is completely deposited in the sealing resin by keeping the device still for several hours, then the heat from the phosphor can be easily discharged toward the mount board, but the phosphor layer is unlikely to cover areas beside and obliquely above the LED element, leading to color unevenness on the light-emitting surface
Solution Approach 1:
The sealing resin is divided into two distinct layers: a dispersion layer containing first particulate phosphor with smaller specific gravity that remains dispersed to cover oblique areas, and a deposition layer containing second particulate phosphor with larger specific gravity that settles on upper surfaces. This segmentation allows each layer to fulfill its specific function - the deposition layer for heat discharge and the dispersion layer for color uniformity.
Solution Approach 2:
Different regions of the sealing resin are assigned different phosphor compositions tailored to local requirements. The deposition layer near the mount board is optimized for heat conduction using high-specific-gravity phosphor, while the dispersion layer in oblique regions uses low-specific-gravity phosphor to maintain light conversion and color uniformity. This local quality differentiation resolves the contradiction between heat discharge and color uniformity.
2Temperature
If the sealing resin is cured after the phosphor is naturally deposited, then the phosphor can be arranged close to the mount board for heat discharge, but large variations between products occur and constantly manufacturing products having the same characteristics is hindered
Solution Approach 1:
The specific gravity parameter of phosphor particles is used as a control variable to achieve automatic separation. By selecting first particulate phosphor with smaller specific gravity and second particulate phosphor with larger specific gravity, the system naturally forms the desired layered structure during the uncured state, eliminating the need for time-controlled intermediate curing and ensuring consistent product characteristics.
3Manufacturing precision
If the phosphor is dispersed in the sealing resin, then the color uniformity is maintained, but the heat from the phosphor is not easily discharged, reducing the life span of the sealing resin and the light-emitting efficiency
Solution Approach 1:
The sealing resin is divided into two distinct layers: a dispersion layer containing first particulate phosphor with smaller specific gravity that remains dispersed to cover oblique areas, and a deposition layer containing second particulate phosphor with larger specific gravity that settles on upper surfaces. This segmentation allows each layer to fulfill its specific function - the deposition layer for heat discharge and the dispersion layer for color uniformity.
Solution Approach 2:
Different regions of the sealing resin are assigned different phosphor compositions tailored to local requirements. The deposition layer near the mount board is optimized for heat conduction using high-specific-gravity phosphor, while the dispersion layer in oblique regions uses low-specific-gravity phosphor to maintain light conversion and color uniformity. This local quality differentiation resolves the contradiction between heat discharge and color uniformity.
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 design allows for effective heat dissipation and uniform light emission, reducing color unevenness and manufacturing variability, while maintaining consistent product characteristics by using a combination of dispersed and deposited phosphors with varying specific gravities and nanoscale fillers.
Implementation Method 1
The first particulate phosphor is dispersed in the dispersion layer among aggregates formed by particles of the nanoscale filler
Implementation Method 2
a deposition layer of the second particulate phosphor on upper surfaces of the mount board and the LED element
Implementation Method 3
Light emitted from the LED element is mixed with light generated by exciting the phosphor with the emitted light, thereby producing light of a desired color
Data Source
AI summary
Provided is a light-emitting device including a mount board, an LED element mounted on the mount board, and a translucent or transparent sealing resin being filled onto the mount board to seal the LED element. The sealing resin contains first and second particulate phosphors excited by emitted light from the LED element, and a nanoscale filler having an average particle size in the range of 1 nm to 100 nm. The specific gravity of the first particulate phosphor is smaller than that of the second particulate phosphor. The sealing resin includes a dispersion layer of the first particulate phosphor covering areas obliquely above and beside the LED element, and a deposition layer of the second particulate phosphor on upper surfaces of the mount board and the LED element. The first particulate phosphor is dispersed in the dispersion layer among aggregates formed by particles of the nanoscale filler.