Coated Optical Semiconductor Element for Uniform White Light
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Solution Overview
Problem
Optical semiconductor light-emitting devices exhibit non-uniform light emission due to different emitting angles, resulting in color unevenness, particularly a yellow ring when viewed from the front, and appear yellow when not emitting light, affecting their appearance.
Innovation Solution
A coated optical semiconductor element is developed using a sheet comprising a white layer with white particles and a light diffusion layer, which provides excellent color uniformity across viewing angles and maintains a white appearance both during and outside light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a phosphor layer is coated on the LED to convert blue light into yellow light, then white light with high energy can be emitted, but color non-uniformity occurs due to different emitting angles, particularly showing a yellow ring when viewed from the front
Solution Approach 1:
The patent divides the encapsulation structure into multiple functional layers: a phosphor layer for wavelength conversion, a transparent resin layer for light transmission, and a reflective layer for light redirection. This segmentation allows each layer to perform its specific function optimally while working together to achieve uniform color emission across different viewing angles.
Solution Approach 2:
The patent introduces a reflective layer at the bottom of the encapsulation structure, adding a vertical dimension to light management. By reflecting light that would otherwise be lost downward back through the phosphor layer, it enhances color uniformity in the forward viewing direction and eliminates the yellow ring effect.
2Use of energy by moving object
If a phosphor layer is coated on the LED, then blue light can be converted into yellow light to create white light, but the device appears yellow when not emitting light, affecting its appearance
Solution Approach 1:
The patent uses a transparent resin layer with specific refractive index properties that allows the encapsulation to appear transparent or white when not emitting light, rather than yellow. The resin layer masks the yellow color of the phosphor when inactive, while still allowing efficient light conversion and transmission when the LED is operating.
3Volume of moving object
If the optical semiconductor light-emitting device is made compact to enhance yield, then device size is reduced, but light emission uniformity across different viewing angles becomes more difficult to achieve
Solution Approach 1:
The transparent resin layer serves multiple functions simultaneously: it provides optical coupling between the LED and the external environment, manages the appearance color when the device is off, and works with the reflective layer to achieve uniform light emission in compact form factors. This multi-functionality allows compact design without sacrificing optical performance.
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 solution ensures uniform light emission and appearance, reducing color unevenness and maintaining a white appearance, thereby enhancing the optical semiconductor element's performance and aesthetic appeal.
Implementation Method 1
a light diffusion layer containing light diffusion particles are arranged on the optical semiconductor element
Implementation Method 2
a white layer containing white particles
Implementation Method 3
a phosphor layer coated on the LED and capable of converting blue light into yellow light
Data Source
Figure 1
Figure 2A~2F
Figure 3A~3B
AI summary
A sheet used for coating an optical semiconductor element is used for directly or indirectly covering an optical semiconductor element, and includes a white layer containing white particles; and a light diffusion layer containing light-diffusing particles, in this order in a thickness direction.