Bare-Chip LED Sealing Structure for Light Extraction and Uniformity
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Solution Overview
Problem
In surface-emitting devices using bare LED chips, the light extraction efficiency is low 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 with a sealing member having a haze value of 4% or more and a thickness greater than the LED element, which contacts 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 device thickness increases due to the required gap between LED and diffusion member
Solution Approach 1:
The sealing member acts as an intermediary component between the LED element and the diffusion member. It provides the necessary mechanical spacing to maintain the gap for luminance uniformity while integrating multiple functions (sealing, spacing, and optical management) into a single component, thereby avoiding additional thickness from separate spacer components.
Solution Approach 2:
The sealing member is designed to perform multiple functions simultaneously: it seals the LED element, provides mechanical spacing to maintain the gap between LED and diffusion member, and manages optical properties. This multi-functionality reduces the overall device thickness by eliminating the need for separate spacer components.
2Illumination intensity
If pins or spacers are placed to maintain a predetermined gap between the LED element and the diffusion member, then luminance uniformity is improved, but light extraction efficiency decreases due to additional interfaces and reflections
Solution Approach 1:
The sealing member integrates multiple functions including sealing, spacing, and optical management into a single component. This eliminates the need for separate pins or spacers that would create additional air interfaces and light reflections, thereby maintaining light extraction efficiency while still achieving luminance uniformity through the integrated spacing function.
Solution Approach 2:
The sealing member is constructed as a composite structure with a light-shielding layer and a transparent layer. This composite design allows it to perform both mechanical spacing and optical management functions, reducing light reflection and absorption losses while maintaining the necessary gap for luminance uniformity.
3Length of stationary object
If a bare LED chip is used without sealing materials, then the display device can be made thinner and higher definition is achieved, but light extraction efficiency is not improved due to high refractive index difference between the transparent substrate and surrounding air
Solution Approach 1:
The sealing member is constructed as a composite structure with a light-shielding layer and a transparent layer. This composite design allows it to perform both mechanical spacing and optical management functions, reducing light reflection and absorption losses while maintaining the necessary gap for luminance uniformity.
Solution Approach 2:
The sealing member acts as an intermediary component between the LED element and the diffusion member. It provides the necessary mechanical spacing to maintain the gap for luminance uniformity while integrating multiple functions (sealing, spacing, and optical management) into a single component, thereby avoiding additional thickness from separate spacer components.
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 device achieves higher light extraction efficiency by reducing light reflection and absorption, enhancing luminance uniformity and reducing thickness.
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
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.