Ceramic Composite Light Conversion Structure for LED Color Tone Control
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Solution Overview
Problem
Conventional white light-emitting diodes using cerium-activated YAG powder and epoxy resin suffer from low brightness due to light absorption and total reflection, resulting in insufficient red component in the color tone, and deterioration issues due to organic materials near the light source.
Innovation Solution
A light conversion structure comprising a ceramic composite with continuously entangled metal oxide phases, including α-Al2O3 and YAG phases, combined with a fluorescent layer for color tone control, which absorbs and emits light to achieve high brightness and reduced deterioration, allowing for the production of warm white light with enhanced red component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a mixture of cerium-activated YAG powder and epoxy resin is used as the fluorescent layer, then the color tone can be adjusted by mixing with red fluorescent powder, but the brightness is reduced due to light absorption and total reflection at the fluorescent powder surface
Solution Approach 1:
The patent uses a composite fluorescent layer combining cerium-activated YAG powder (yellow emission) and red fluorescent powder in specific proportions (YAG:Ce 90-99 wt%, red fluorescent powder 1-10 wt%). This composite material approach allows simultaneous achievement of warm white color tone (reducing blue-green dominance) and improved brightness by optimizing the balance between color conversion and light transmission
Solution Approach 2:
The patent optimizes multiple parameters including the weight ratio of fluorescent powders, layer thickness (5-50 μm), and refractive index matching between the resin and fluorescent materials. By changing these parameters, the patent reduces total internal reflection and light absorption losses while maintaining the desired warm white color tone
2Reliability
If organic resin is used as the binder for fluorescent powder, then the fluorescent substances can be dispersed and coated, but deterioration occurs due to use of organic material near the light source
Solution Approach 1:
The patent replaces organic epoxy resin with inorganic transparent resin materials such as glass resin or ceramic-based resins. This material substitution eliminates the deterioration issues associated with organic materials near the high-temperature light source, significantly improving the service life and reliability of the light-emitting device
Solution Approach 2:
The use of inorganic resin materials creates a more stable and inert environment for the fluorescent powder particles, protecting them from degradation caused by heat and UV radiation from the blue LED light source, thereby extending the operational lifetime of the device
3Device complexity
If YAG:Ce fluorescent powder is used alone, then the structure is simple, but the color tone is insufficient in red component and appears white mixed with blue-green
Solution Approach 1:
The patent creates a composite fluorescent system by combining YAG:Ce powder (emitting yellow light at 560-580 nm) with red fluorescent powder (emitting at 610-680 nm). This composite approach maintains relatively simple device structure while significantly improving color quality by adding the red component, achieving warm white light with better color rendering
Solution Approach 2:
The patent applies local quality by using different fluorescent materials with specific emission characteristics in different proportions within the same fluorescent layer. The red fluorescent powder is specifically selected and positioned to supplement the red component locally, creating warm white light without requiring complete restructuring of the device
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 high transmittance and brightness while controlling the color tone, achieving a warm white light-emitting diode with improved durability and color mixing, overcoming the limitations of conventional technologies.
Implementation Method 1
a layer formed of a ceramic composite, which absorbs a part of a first light to emit a second light
Implementation Method 2
a fluorescent layer for the control of color tone, which absorbs a part of the first light or a part of the second light to emit a third light
Implementation Method 3
transmits a part of the first light
Implementation Method 4
transmits a part of the first light or a part of the second light
Data Source
AI summary
A light conversion structure ensuring good light transmission and less deterioration and capable of controlling light to a desired color tone and emitting a highly bright light, and a light-emitting device using the same. The light conversion structure is a light conversion structure including a layer formed of a ceramic composite, which absorbs a part of a first light to emit a second light and transmits a part of the first light, and a fluorescent layer for the control of color tone, which is formed on the surface of the ceramic composite and which absorbs a part of the first light or a part of the second light to emit a third light and transmits a part of the first light or a part of the second light, wherein the ceramic composite includes a solidified body where at least two or more metal oxide phases are formed continuously and three-dimensionally entangled with each other, and at least one metal oxide phase in the solidified body includes a metal element oxide capable of emitting fluorescence.