LED Package Gradient Refractive Index Encapsulation
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Solution Overview
Problem
Conventional light-emitting diode (LED) packages suffer from significant Fresnel loss and total reflection loss due to the large difference in refractive indices between the encapsulation material and the LED chip and the environment, leading to reduced light extraction efficiency.
Innovation Solution
A light-emitting element package device with a light-pervious encapsulation layer that incorporates materials with different refractive indices, gradually reducing the refractive index from the LED chip interface to the environmental interface, minimizing the refractive index difference and thereby reducing Fresnel and total reflection losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a uniform encapsulation material with single refraction index is used, then the device structure is simple, but Fresnel loss and total reflection loss increase due to large refraction index difference at interfaces
Solution Approach 1:
The encapsulation layer is divided into multiple regions with different refraction indices. The first encapsulation layer has refraction index n1, the second has n2, and the third has n3, where n1 > n2 > n3. This local variation in refraction index reduces the refraction index difference at each interface, thereby reducing Fresnel loss and total reflection loss while maintaining a relatively simple overall structure.
Solution Approach 2:
The refraction index parameter is changed progressively across different encapsulation layers. By creating a gradient structure where the refraction index decreases from the LED chip interface toward the external environment, the patent optimizes light extraction efficiency. This parameter change approach transforms the uniform refraction index into a spatially varying parameter that minimizes optical losses.
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 significantly enhances light extraction efficiency by minimizing refractive index differences at interfaces, resulting in improved light output and reduced losses.
Implementation Method 1
According to the theory of Fresnel loss, the light extraction efficiency equals to 4/[2+(n1/n2)+(n2/n1)], wherein n1 and n2 represent the refraction indexes of two materials bordered and having an interface therebetween. When an interface formed between two different materials, the more the difference between the two refraction indexes is, the more the Fresnel loss is.
Implementation Method 2
at the interface, a total reflection loss may also occur when a light is incident onto a material having a low refraction index (n2) from a material having a high refraction index (n1). The light extraction efficiency is proportional to (n2/n1)2.
Implementation Method 3
the refraction index of the encapsulation layer is gradually reduced from the bottom portion upward to the top portion of the encapsulation layer
Data Source
AI summary
The present invention discloses a surface mount type light-emitting diode package device and a light-emitting element package device. In the device, the encapsulation layer comprises an encapsulation material and at least one material having a refraction index different from the encapsulation material distributed therein. The distribution of the material having a refraction index different from the encapsulation material is in a way such that the refraction index of the encapsulation layer is gradually reduced from the bottom portion upward to the top portion or the inner portion outward to the outer portion of the encapsulation layer. Accordingly, a difference between the refraction indexes of two adjoining media can be reduced to eliminate a total reflection and the Fresnel loss and enhance light extraction efficiency.