LED Cover Layer Layout for Higher Light Extraction Efficiency
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Solution Overview
Problem
Existing light emitting devices have limited luminous efficacy, which can be improved by optimizing the arrangement and materials used in the light emitting elements and cover members.
Innovation Solution
A light emitting device comprising multiple light emitting elements with light transmissive members on their upper surfaces, a mounting board, a first cover member with a reflective material layer between the elements and a light transmissive layer between the transmissive members, and a second cover member with a reflective material around the elements, manufactured using a method that involves applying a first resin with centrifugal force to form the reflective and transmissive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a light emitting device uses conventional cover members without optimized reflective material distribution, then the device structure is simple, but the luminous efficacy is limited
Solution Approach 1:
The patent applies local quality by creating distinct regions within the cover member: a first reflective material containing layer with high reflective material concentration positioned between light emitting elements, and a light transmissive layer with lower reflective material concentration positioned between light transmissive members. This spatial variation in material distribution optimizes light reflection in specific areas while maintaining light transmission in other areas, thereby improving luminous efficacy without requiring completely separate components.
Solution Approach 2:
The cover member is constructed as a composite material structure combining resin matrix with dispersed reflective materials (such as titanium oxide, zinc oxide, or barium sulfate) at different concentrations in different regions. This composite approach allows the single cover member to simultaneously perform multiple functions: reflecting light between elements, transmitting light between members, and providing structural support, thus improving luminous efficacy while avoiding increased device complexity.
2Loss of energy
If reflective material is uniformly distributed in the cover member, then the manufacturing process is simple, but light extraction efficiency is not optimized
Solution Approach 1:
Instead of uniform distribution, the patent implements local quality by concentrating reflective material in the first reflective material containing layer between light emitting elements where light reflection is most needed, while using a light transmissive layer with reduced reflective material between light transmissive members where light transmission is prioritized. This non-uniform distribution significantly improves light extraction efficiency by directing reflected light toward useful paths.
Solution Approach 2:
The patent replaces complex multi-step manufacturing processes (such as separate application of reflective coatings, multiple lamination steps, or precision positioning of reflective sheets) with a simplified single-mold injection process. By designing the mold to directly form the cover member with the desired non-uniform reflective material distribution during injection, the complex material arrangement is achieved automatically through the molding process itself, maintaining ease of manufacture while enabling optimized light extraction.
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 described configuration enhances light extraction efficiency and luminous efficacy by effectively reflecting and transmitting light, resulting in a higher output of the light emitting device.
Implementation Method 1
The first cover member comprises a first reflective material containing layer disposed between the light emitting elements and containing a first reflective material
Implementation Method 2
The first cover member further comprises a light transmissive layer disposed between the light transmissive members
Implementation Method 3
settling the first reflective material in the first resin using a centrifugal force so as to form a first reflective material containing layer containing the first reflective material between the light emitting elements
Data Source
AI summary
A light emitting device includes: a mounting board; a plurality of light emitting elements disposed on the mounting board; a plurality of light transmissive members, each located on an upper surface of a respective one of the light emitting element; a first cover member located on or above the mounting board, the first cover member including: a first reflective material containing layer disposed between the light emitting elements and containing a first reflective material, and a light transmissive layer disposed between the light transmissive members; and a second cover member disposed around the light emitting elements.