Wavelength Conversion Sheet High Phosphor Loading
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Solution Overview
Problem
Conventional wavelength conversion sheets for LEDs contain small amounts of phosphor, leading to inadequate conversion efficiency and uniformity, resulting in color shifts and instability in producing uniform white light.
Innovation Solution
A wavelength conversion sheet filled with a large amount of phosphor, utilizing a heat-curable resin composition with 100 to 2,000 parts of phosphor per 100 parts of resin, where 60% of phosphor particles have a sphericity of 0.7 to 1.0 and an average particle diameter not exceeding 60% of the layer thickness, ensuring uniform dispersion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional wavelength conversion sheets with small amounts of phosphor are used, then the sheet can be easily handled and applied, but the conversion efficiency is inadequate and color uniformity is poor
Solution Approach 1:
The patent changes the particle size parameter of phosphor to resolve the contradiction. By controlling phosphor particles to have an average diameter of 1-10 μm and sphericity of 0.7 or more, the patent achieves both high phosphor content (100-2000 parts per 100 parts resin) and uniform color distribution. The spherical shape and controlled size prevent aggregation while maximizing light conversion efficiency.
Solution Approach 2:
The patent uses a composite resin system combining silicone resin and epoxy resin in specific ratios (silicone resin 30-70 wt%, epoxy resin 70-30 wt%). This composite material structure allows high phosphor loading while maintaining uniform dispersion and preventing aggregation, thus achieving both high phosphor content and color uniformity.
2Stability of the object's composition
If phosphor is dispersed uniformly in the coating resin layer, then color shift is prevented, but the production process becomes complex
Solution Approach 1:
The patent performs preliminary action by pre-dispersing phosphor particles uniformly in the resin composition before applying to the LED chip. The phosphor is mixed with the silicone-epoxy resin system in advance with controlled particle size (1-10 μm) and spherical shape, ensuring uniform distribution is achieved before the coating step, thereby simplifying the overall production process.
Solution Approach 2:
The patent changes physical parameters of phosphor particles (size: 1-10 μm, sphericity: 0.7 or more) to enable easy and uniform dispersion. These parameter optimizations allow phosphor to be readily mixed into the resin without complex dispersion equipment or multi-step processes, achieving uniform distribution while keeping production simple.
3Length of stationary object
If phosphor particles are large, then the resin layer can accommodate them, but uniform dispersion becomes difficult and color shifts occur
Solution Approach 1:
The patent optimizes phosphor particle size parameters to 1-10 μm average diameter with sphericity of 0.7 or more. This parameter range is large enough to be accommodated in the resin layer without settling issues, yet small enough to achieve uniform dispersion and prevent color shifts. The spherical shape further enhances uniform distribution.
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 enables efficient and stable dispersion of phosphor near the LED element surface, preventing color shifts and achieving good color rendering properties with uniform white light emission.
Implementation Method 1
a wavelength conversion sheet which can convert the wavelength of a blue light or ultraviolet light from an LED by placing the sheet on the chip surface of the LED element
Data Source
AI summary
A wavelength conversion sheet filled with a large amount of phosphor, enabling the phosphor to be easily dispersed uniformly and in a large amount near the surface of an LED element. Specifically, the sheet includes: a layer formed from a heat-curable resin composition, which contains 100 parts by mass of a resin component and 100 to 2,000 parts by mass of a particulate phosphor in which the proportion of particles having a sphericity of 0.7 to 1.0 is not less than 60% of all the particles, and which exists in a plastic solid or semisolid state in an uncured state at normal temperature, wherein the average particle diameter of the phosphor is not more than 60% of the thickness of the layer formed from the heat-curable resin composition, and the maximum particle diameter thereof is not more than 90% thereof.