LED Package Encapsulant With Refractive Index Gradient for Light Loss
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Solution Overview
Problem
Conventional LED packages face challenges in efficiently utilizing sideward light due to limited space for reflective plates in miniaturized products and non-uniform reflection using resin reflective cups, leading to significant light loss and reduced luminance.
Innovation Solution
An LED package with a refractive index gradient in the encapsulant that increases continuously from the peripheral surface to the central axis, allowing for efficient refraction and redirection of sideward light without the need for a separate reflective cup, utilizing materials like polymer resin or glass and optionally incorporating a reflecting cup with high refractive index oxide powder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective plate with metal film is used to reflect sideward light, then light reflection efficiency is improved, but package thickness increases due to space requirements for appropriate installation angle
Solution Approach 1:
The patent changes the refractive index parameter of the encapsulant material by incorporating oxide powder (such as TiO2) with high refractive index into the resin matrix. This creates a resin reflective cup with enhanced optical properties that can reflect light effectively without requiring the thickness and installation space of a metal-coated reflective plate
Solution Approach 2:
The patent replaces the mechanical reflective plate structure (requiring specific installation angle and space) with an optically-enhanced resin material that provides reflection functionality through its refractive index properties, eliminating the need for separate reflective components and reducing package thickness
2Length of moving object
If a resin reflective cup with oxide powder is used instead of metal-coated reflective plate, then package thickness is reduced, but light reflection uniformity deteriorates and reflection ratio decreases
Solution Approach 1:
The patent applies local quality by concentrating the oxide powder particles specifically in the peripheral region of the encapsulant where sideward light reflection is most needed. This creates a refractive index gradient with higher concentration at the periphery and lower concentration toward the center, optimizing reflection uniformity and efficiency while maintaining reduced package thickness
3Ease of manufacture
If conventional resin encapsulant with uniform refractive index is used, then manufacturing is simple, but sideward light utilization is poor causing light loss
Solution Approach 1:
The patent introduces local quality variation in the encapsulant by creating a refractive index gradient through non-uniform distribution of oxide powder particles. The peripheral region has higher oxide powder concentration for enhanced reflection, while the central region has lower concentration, optimizing both light utilization and maintaining manufacturing feasibility
Solution Approach 2:
The patent creates a composite encapsulant material by combining resin matrix with dispersed oxide powder particles (such as TiO2). This composite structure provides both the structural integrity of resin and the high refractive index properties of oxide powder, enabling effective sideward light reflection while maintaining ease of manufacture through conventional mixing and molding processes
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 maximizes light directivity and luminance while minimizing light loss, enabling effective utilization of sideward light and facilitating miniaturization of LED packages.
Implementation Method 1
an encapsulant formed on the package substrate to encapsulate the light emitting diode chip, wherein the encapsulant has a refractive index gradient with refractive indices continuously increasing from a peripheral surface thereof to a central axis thereof
Data Source
AI summary
A light emitting diode package with reduced light loss includes a package substrate, a light emitting diode chip mounted on the package substrate and an encapsulant formed on the package substrate to encapsulate the light emitting diode chip. The encapsulant has a refractive index gradient with refractive indices continuously increasing from a peripheral surface thereof to a central axis thereof.