Micro LED Reflective Layer Layout for Higher Light Extraction
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Solution Overview
Problem
Existing display apparatuses with micro-sized light-emitting diodes (micro LEDs) face challenges in efficiently extracting light to the display surface due to the absence of reflective layers on the back surface side, limiting light output to the display surface.
Innovation Solution
A display apparatus is designed with a translucent substrate, where light-emitting elements are mounted on the back surface with an adhesive layer, and a reflective layer is strategically positioned to cover the protective film, overlapping the light-emitting elements and their side surfaces, electrically coupled through contact holes to enhance light reflection and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If no reflective layer is provided on the back surface side of light-emitting diodes, then the mounting structure can be simplified, but light extraction efficiency to the display surface is reduced
Solution Approach 1:
The reflective layer is extended from a simple back-surface coating to a three-dimensional structure that includes side portions covering the side surfaces of the protective film. This dimensional extension allows the reflective layer to capture and redirect light from multiple directions (back surface and side surfaces) toward the display surface, thereby improving light extraction efficiency without complicating the mounting structure
Solution Approach 2:
The reflective layer serves multiple functions: it reflects light from the back surface of the protective film, reflects light from the side surfaces of the protective film, and directs both toward the display surface. This multi-functional design addresses the light extraction issue comprehensively while maintaining structural simplicity
2Loss of energy
If a reflective layer is added to improve light extraction, then light extraction efficiency is improved, but the device structure becomes more complex
Solution Approach 1:
The reflective layer is integrated with the protective film structure, where the protective film and reflective layer form a unified assembly. The reflective layer is provided on the protective film in a continuous manner, merging the protective function and light reflection function into a single integrated structure, thereby improving light extraction without significantly increasing device complexity
3Device complexity
If the reflective layer covers only the back surface, then the structure is simpler, but light from side surfaces cannot be reflected to the display surface
Solution Approach 1:
The reflective layer design transitions from a two-dimensional back-surface coating to a three-dimensional structure with both back surface coverage and side surface coverage. The side portions of the reflective layer extend along the side surfaces of the protective film, enabling light from side directions to be reflected toward the display surface, thus improving light extraction efficiency
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
This configuration improves light extraction efficiency by reflecting light from both the side and back surfaces to the display surface, reducing color mixture between pixels and simplifying the multilayer structure.
Implementation Method 1
a plurality of light-emitting elements provided on the second main surface of the substrate with an adhesive layer interposed between the light-emitting elements and the second main surface
Implementation Method 2
a first reflective layer provided to cover the first protective film and having an overlapping portion overlapping the light-emitting element and a side portion provided to a side surface of the groove
Implementation Method 3
a translucent substrate having a first main surface serving as a display surface and a second main surface opposite to the first main surface
Implementation Method 4
The first reflective layer is electrically coupled to the first terminal through a first contact hole formed in the first protective film
Data Source
AI summary
A display apparatus includes a translucent substrate having a first main surface serving as a display surface and a second main surface opposite to the first main surface, a plurality of light-emitting elements provided to the second main surface of the substrate with an adhesive layer interposed between the light-emitting elements and the second main surface, a first terminal and a second terminal provided on a side of each of the light-emitting elements opposite to the substrate, a first protective film covering the light-emitting elements and having a groove between the light-emitting elements adjacent to each other, and a first reflective layer provided to cover the first protective film and having an overlapping portion overlapping the light-emitting element and a side portion provided to a side surface of the groove.