Light Emitting Device Package with Thermal Insulation
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Solution Overview
Problem
Existing white light emitting diodes (LEDs) using YAG:Ce phosphor have limitations in adjusting color coordinates, correlated color temperature (CCT), and color rendering index (CRI), resulting in relatively low CCT and CRI, making it difficult to achieve desired color temperatures and rendering indices for various lighting applications.
Innovation Solution
A light emitting device package with a light conversion part on the cover part, separated from the light emitting chip, includes a heat transfer layer and adiabatic layers to prevent heat transfer, allowing for easy fabrication and improved reliability and durability by avoiding direct heat exposure to the light conversion part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the light conversion part is placed close to the light emitting chip to improve light conversion efficiency, then the light conversion efficiency is improved, but the light conversion part is exposed to high heat which causes denaturation and reduces reliability
Solution Approach 1:
The patent divides the package structure into distinct functional zones: the light emitting chip is separated from the light conversion part by a reflective well and encapsulant. This segmentation allows the light emitting chip to operate at high temperatures while the light conversion part is positioned in a cooler region, maintaining both high light conversion efficiency and reliability.
Solution Approach 2:
The patent introduces an intermediary structure (reflective well filled with encapsulant) between the light emitting chip and the light conversion part. This intermediary serves as a thermal barrier that blocks heat transfer from the chip to the phosphor, while still allowing optical coupling for efficient light conversion.
2Reliability
If the light conversion part is separated from the light emitting chip to prevent heat transfer, then reliability is improved, but light conversion efficiency decreases
Solution Approach 1:
The reflective well structure serves multiple functions simultaneously: it acts as a thermal barrier to protect the phosphor from heat, provides optical reflection to improve light extraction efficiency, and maintains the structural integrity of the package. This multi-functionality resolves the contradiction between heat isolation and light conversion efficiency.
Solution Approach 2:
The patent utilizes the optical properties of the encapsulant material to enhance light conversion efficiency despite the physical separation. The encapsulant is selected to have appropriate refractive index and transparency to maximize light coupling between the chip and phosphor while maintaining thermal isolation.
3Ease of manufacture
If only YAG:Ce phosphor is used to simplify the structure, then manufacturing is easier, but color temperature and CRI adjustment becomes difficult
Solution Approach 1:
The patent employs multiple phosphors with different emission characteristics that can be independently adjusted in concentration and distribution. This dynamic composition allows the light emitting device to achieve various color temperatures and CRI values by simply changing the phosphor ratios, maintaining ease of manufacture while providing versatile color control.
Solution Approach 2:
The patent uses a composite phosphor system combining YAG:Ce with other phosphors (such as red phosphors like CaAlSiN3 or K2SiF6:Mn4+). This composite approach enables independent optimization of color temperature and CRI while maintaining a relatively simple manufacturing process, as all phosphors can be mixed in the encapsulant material.
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 easy fabrication of the light emitting device package, enhances reliability by preventing heat-induced denaturation of the light conversion part, and improves durability, allowing for better control over color temperature and rendering index.
Implementation Method 1
a heat transfer layer and adiabatic layers to prevent heat transfer
Implementation Method 2
a light conversion part provided on a bottom surface of the cover part while being separated from the light emitting chip
Data Source
AI summary
Disclosed is a light emitting device package. The light emitting device package includes a body part provided therein with a cavity, a light emitting chip in the cavity, a cover part to cover the cavity, and a light conversion part provided on a bottom surface of the cover part while being separated from the light emitting chip.