Surface-Emitting LED Sealing Structure for Higher Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional surface-emitting devices using bare LED chips suffer from low light extraction efficiency due to high refractive index differences between the transparent substrate and surrounding air, leading to significant light reflection and absorption.
Innovation Solution
A surface-emitting device design that includes a sealing member with a haze value of 4% or more and a thickness greater than the LED element, contacting the transparent substrate on both the side and opposite surfaces to reduce refractive index differences and minimize light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a diffusion member is placed on the upper side of the LED element to suppress luminance unevenness, then luminance uniformity is improved, but the gap between the LED element and diffusion member increases device thickness
Solution Approach 1:
A resin layer with a refractive index between that of the LED element and the diffusion member is introduced as an intermediary substance. This resin layer fills the gap between the LED element and diffusion member, enabling light to pass through more efficiently while maintaining the necessary separation distance, thus improving luminance uniformity without excessively increasing device thickness.
Solution Approach 2:
The refractive index of the resin layer is specifically controlled to be between the refractive indices of the LED element and the diffusion member. By optimizing this parameter, the optical impedance mismatch is reduced, allowing for better light transmission and improved luminance uniformity while minimizing the gap distance and resulting device thickness.
2Illumination intensity
If pins or spacers are placed to maintain a predetermined gap between the LED element and diffusion member, then luminance uniformity is improved, but light extraction efficiency of the LED element decreases
Solution Approach 1:
The resin layer serves as an optical intermediary that replaces the need for pins or spacers. Instead of using discrete mechanical support elements that block light, the resin continuously fills the gap, allowing light to pass through the entire gap region without obstruction, thereby maintaining luminance uniformity while preserving light extraction efficiency.
Solution Approach 2:
The mechanical support system (pins or spacers) is replaced with an optical medium (resin layer). This substitution eliminates the mechanical obstruction to light while still maintaining the necessary gap for luminance uniformity, effectively converting a mechanical solution into an optical one that does not impede light extraction.
3Length of stationary object
If the LED element and diffusion member are placed close together to reduce device thickness, then device thickness is reduced, but luminance uniformity deteriorates
Solution Approach 1:
The refractive index of the resin layer is optimized to match intermediate values between the LED element and diffusion member. This parameter optimization allows for reduced gap distance (and thus reduced device thickness) while maintaining sufficient light diffusion capability to ensure luminance uniformity, as the resin's optical properties compensate for the shorter propagation distance.
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
Improves light extraction efficiency by reducing light absorption and reflection, enhancing the overall performance of the display device.
Implementation Method 1
the refractive index difference between the transparent substrate and surrounding air is large, as the result, the reflectance of the light emitted from the light-emitting layer reflected on the interface of the transparent substrate and the surrounding air is high
Implementation Method 2
the reflectance of the light emitted from the light-emitting layer reflected on the interface of the transparent substrate and the surrounding air is high, so that the light extraction efficiency is decreased
Data Source
AI summary
A surface-emitting device includes: a light-emitting diode substrate including a supporting substrate, and a light-emitting diode element placed on one surface side of the supporting substrate; and a sealing member placed on a light-emitting diode element side surface of the light-emitting diode substrate, and configured to seal the light-emitting diode element; wherein the light-emitting diode element includes a transparent substrate including inorganic material, and a light-emitting layer formed on one surface of the transparent substrate; the light-emitting diode element is a bare chip in which the transparent substrate is exposed on a surface thereof; the sealing member is in contact with the transparent substrate on a side surface and a surface opposite side to a surface where the light-emitting layer is formed; and a haze value of the sealing member is 4% or more, and a thickness thereof is thicker than a thickness of the light-emitting diode element.