Moisture-Resistant LED Package with Fluoride Red Phosphor
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Solution Overview
Problem
Fluoride-based and sulfide-based red phosphors used in light-emitting diodes (LEDs) are vulnerable to moisture, leading to discoloration over time, which affects the color reproduction of lighting systems.
Innovation Solution
A light source package is designed with a substrate, a light-emitting device, a red phosphor layer, and an encapsulation layer, where the red phosphor layer is coated on the light-emitting device and surrounded by the encapsulation layer, preventing moisture from reaching the phosphors, and the matrix of the red phosphor layer is formed from the same material as the encapsulation layer to ensure thermal stability and maintain light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If fluoride-based or sulfide-based red phosphors are used in LED, then excellent color reproduction is achieved, but the phosphors are vulnerable to moisture and discolor over time
Solution Approach 1:
The patent divides the phosphor application into two distinct layers: a red phosphor layer applied to the light-emitting device surface, and a separate encapsulation layer that surrounds both the light-emitting device and the red phosphor layer. This segmentation allows the red phosphor to perform its color conversion function while the encapsulation layer provides moisture protection, resolving the contradiction between color reproduction and moisture resistance.
Solution Approach 2:
The encapsulation layer acts as an intermediary barrier between the moisture-sensitive red phosphor and the external environment. This intermediate layer prevents direct contact between moisture and the phosphor, thereby protecting the phosphor's optical properties while allowing the system to maintain excellent color reproduction.
2Reliability
If encapsulation layer is added to protect phosphor from moisture, then moisture resistance is improved, but light extraction efficiency may be compromised
Solution Approach 1:
The encapsulation layer is designed as a thin film structure that provides moisture protection while maintaining optical transparency. The thin film configuration allows light to pass through with minimal absorption or scattering, thus protecting the phosphor from moisture without significantly compromising light extraction efficiency.
Solution Approach 2:
The patent optimizes the optical parameters of the encapsulation layer, specifically its transparency and thickness, to balance protection and light extraction. By carefully controlling these parameters, the encapsulation layer provides effective moisture barrier functionality while minimizing its impact on light extraction efficiency.
3Illumination intensity
If red phosphor layer is coated on light-emitting device, then color conversion is improved, but thermal stability may be affected
Solution Approach 1:
The patent employs composite material structures in two ways: first, the red phosphor is combined with a matrix material to form a red phosphor layer with improved thermal stability; second, the encapsulation layer material is selected to match the thermal expansion characteristics of the red phosphor, creating a composite system that maintains stability under thermal stress while enabling effective color conversion.
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 effectively prevents moisture-induced discoloration, ensuring excellent color reproduction and stability of the light source package over a long period without compromising light extraction efficiency.
Implementation Method 1
a red phosphor layer formed adjacent a surface of the light-emitting device
Implementation Method 2
an encapsulation layer for encapsulating the light-emitting device and the red phosphor layer
Data Source
AI summary
Provided are a light source package and a display device including the light source package. The light source package includes a substrate; a light-emitting device mounted on the substrate; a red phosphor layer formed adjacent to a surface of the light-emitting device; and an encapsulation layer for encapsulating the light-emitting device and the red phosphor layer, wherein a phosphor of the red phosphor layer is a fluoride-based red phosphor or a sulfide-based red phosphor. The light source package and the display device including the light source package display excellent color reproduction, without discoloration due to moisture after a long period of time.