LED Mount Multi-Layer Reflector Light Extraction
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Solution Overview
Problem
Current light emitting devices, such as LEDs, face inefficiencies in light extraction due to absorption by the mount and encapsulant materials, which reduces overall brightness and efficiency.
Innovation Solution
A semiconductor light emitting diode (LED) is attached to a mount with a multi-layer reflector comprising alternating low and high index of refraction materials, and a non-reflective top surface, along with a lens having a lower index of refraction than the LED, to enhance light extraction and reduce absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a reflective layer is added to redirect light, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent uses a multi-layer composite structure consisting of alternating high-index and low-index dielectric layers formed over the mount. This composite material approach creates a distributed Bragg reflector that achieves superior light extraction efficiency through constructive and destructive interference patterns, resolving the contradiction by using material composition rather than simple geometric modifications.
Solution Approach 2:
The patent optimizes the thickness of each dielectric layer to be approximately one-quarter of the wavelength of light in that medium, and carefully selects the refractive index contrast between alternating layers. These parameter changes create a photonic bandgap structure that reflects specific wavelengths while transmitting others, achieving high light extraction efficiency without excessive structural complexity.
2Reliability
If mount material is used for electrical connection, then electrical conductivity is improved, but light absorption increases
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary between the electrically conductive mount and the LED. This intermediate layer with optimized refractive index serves as a mediator that maintains electrical connectivity while reducing optical absorption and improving light extraction, thus resolving the contradiction between electrical conductivity and light absorption.
Solution Approach 2:
The patent applies different material properties to different regions: the mount remains highly conductive for electrical connection, while the overlying dielectric layers are optimized for optical properties. This local differentiation of material quality allows the system to simultaneously achieve excellent electrical connectivity and minimal light absorption.
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 improves light extraction efficiency by redirecting and reflecting unconverted light, increasing the overall brightness and efficiency of the LED device.
Implementation Method 1
A multi-layer reflector is disposed on the top surface of the mount adjacent to the LED. The multi-layer reflector includes layer pairs of alternating layers of low index of refraction material and high index of refraction material.
Implementation Method 2
The multi-layer reflector includes layer pairs of alternating layers of low index of refraction material and high index of refraction material
Implementation Method 3
A lens is disposed over the LED and the layer. The layer has an index of refraction lower than the index of refraction of the lens.
Data Source
Figure 1~7
AI summary
Embodiments of the invention include a semiconductor light emitting diode (LED) attached to a top surface of a mount. A multi-layer reflector is disposed on the top surface of the mount adjacent to the LED. The multi-layer reflector includes layer pairs of alternating layers of low index of refraction material and high index of refraction material. A portion of the top surface in direct contact with the multi-layer reflector is non-reflective.