Micro LED Bragg Reflector Structure for Higher Light Conversion Efficiency
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Solution Overview
Problem
Micro LED display devices suffer from insufficient luminous efficiency due to a considerable difference between converted and original light, leading to reduced brightness.
Innovation Solution
Incorporation of a Bragg reflection element with specific layer pair configurations to enhance transmission efficiency of visible light and filtering effect of ultraviolet light, utilizing layer pairs with varying thicknesses and refractive indices to minimize interference ripples and improve light purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional micro LED display device is used, then the device structure is simple, but the luminous efficiency is insufficient due to considerable difference between converted light and original light
Solution Approach 1:
A Bragg reflection element is introduced as an intermediary component between the light emitting layer and color conversion layer. This element includes multiple layer pairs with alternating high and low refractive indices that act as an optical mediator to reflect ultraviolet light back to the color conversion layer while allowing visible light to pass through, thereby improving luminous efficiency without significantly complicating the device structure
Solution Approach 2:
The patent optimizes specific parameters of the Bragg reflection element including the thickness of each layer (controlled within specific ranges relative to wavelength and refractive index), the refractive index contrast between alternating layers, and the number of layer pairs. These parameter optimizations enable the element to achieve high reflectivity for ultraviolet light while maintaining high transmissivity for visible light, resolving the contradiction between structural simplicity and luminous efficiency
2Loss of energy
If the Bragg reflection element is added to improve luminous efficiency, then the transmission efficiency of visible light is enhanced, but the device complexity increases
Solution Approach 1:
The Bragg reflection element is segmented into multiple discrete layer pairs, each with specific thickness and refractive index properties. This segmentation allows the element to be integrated into the existing micro LED display structure as a modular component, achieving improved luminous efficiency while keeping the overall device complexity manageable through systematic division of the optical function
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 Bragg reflection element increases luminous efficiency by maintaining high transmissivity for visible light and reflectivity for ultraviolet light, effectively reducing interference and enhancing overall brightness.
Implementation Method 1
a first Bragg reflection element located on the color conversion layer. The first Bragg reflection element includes a plurality of layer pairs
Implementation Method 2
the color conversion layer includes a red wavelength conversion material, a green wavelength conversion material and a blue wavelength conversion material that are corresponding to the ultraviolet LEDs respectively, such that the ultraviolet lights are converted into a red light, a green light and a blue light respectively
Implementation Method 3
Each of the layer pairs includes at least one first layer and at least one second layer alternately stacked. A refractive index of the first layer is greater than a refractive index of the second layer
Data Source
AI summary
A micro LED display device includes a light emitting layer, a color conversion layer located on a light emitting surface of the light emitting layer, and a Bragg reflection element located on the color conversion layer. The Bragg reflection element includes a plurality of layer pairs. Each of the layer pairs includes at least one first layer and at least one second layer alternately stacked. The layer pairs include a top layer pair, a bottom layer pair and a plurality of middle layer pairs between the top layer pair and the bottom layer pair. A thickness of the first layer of each of the middle layer pairs is smaller than a thickness of the second layer of each of the middle layer pairs. A refractive index of the first layer is greater than a refractive index of the second layer.