Micro LED Display Structure With Reflective Wavelength Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image display devices face challenges in forming a minute pattern of the wavelength conversion layer due to its large thickness requirement, which complicates the production of reflection and transmission layers, especially on substrates with low flatness, leading to instability and increased production steps.
Innovation Solution
An image display device configuration with a reflection layer integrated inside the nitride semiconductor layer of micro LED elements, which reflects down-converted light, and a transmission layer on the emission side, efficiently emitting long-wavelength light while confining excitation light, thereby reducing the thickness of the wavelength conversion layer and simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a wavelength conversion layer with very large thickness is used to absorb excitation light, then wavelength conversion efficiency is improved, but manufacturing precision deteriorates due to difficulty in forming minute patterns
Solution Approach 1:
The patent introduces a reflection layer disposed beneath the wavelength conversion layer to reflect excitation light back through the layer, enabling sufficient absorption in a thinner layer. This dimensional approach (adding depth via reflection) resolves the contradiction by achieving high conversion efficiency without requiring large thickness that would compromise pattern formation precision.
2Loss of energy
If a dielectric multilayer film is used as reflection layer, then light reflection efficiency is improved, but device complexity increases due to complex structure formation requirements
Solution Approach 1:
The patent changes the material parameter from complex dielectric multilayer films to simple metal films (Al, Ag, Au) or semiconductor layers with inherent reflective properties. This parameter change maintains high reflection efficiency while dramatically reducing structural complexity and easing fabrication requirements.
Solution Approach 2:
The patent employs simple, easily deposited metal reflection layers that can be formed using conventional sputtering or evaporation techniques, replacing complex dielectric structures. This simplifies the overall device structure and reduces manufacturing complexity while maintaining functional performance.
3Loss of energy
If a dielectric multilayer film is used as reflection layer, then light reflection efficiency is improved, but ease of manufacture deteriorates due to difficulty in forming on non-flat substrates
Solution Approach 1:
The patent changes the reflection layer material from dielectric multilayer films to metal films or semiconductor layers that can be deposited conformally on non-flat substrates using sputtering or evaporation. This parameter change enables easy manufacture on LED chips with varying surface topography while maintaining high reflection efficiency.
4Ease of manufacture
If wavelength conversion layer thickness is reduced, then ease of manufacture is improved, but wavelength conversion efficiency deteriorates
Solution Approach 1:
The patent adds a reflection layer beneath the wavelength conversion layer to create an optical cavity effect, reflecting excitation light back through the conversion layer. This dimensional addition enables thin conversion layers to achieve high efficiency, resolving the contradiction between reduced thickness for ease of manufacture and maintained conversion 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 allows for a stable and efficient production of image display devices with improved light extraction efficiency, reduced light crosstalk, and enhanced color purity, while minimizing the number of production steps and material usage.
Implementation Method 1
a wavelength conversion layer configured to convert ultraviolet light into visible light of red, green, and blue
Implementation Method 2
micro LED elements, which are minute LED elements
Implementation Method 3
a first multilayer film that reflects the long-wavelength light converted by the wavelength conversion layer
Data Source
AI summary
An image display device includes a drive circuit substrate, micro LED elements, and a wavelength conversion layer that converts excitation light emitted from the micro LED elements and that emits converted long-wavelength light to a side opposite to the drive circuit substrate, the micro LED elements and the wavelength conversion layer being sequentially stacked on the drive circuit substrate. The micro LED elements include a first multilayer film that reflects the long-wavelength light converted by the wavelength conversion layer.