Quantum Dot Backlight Structure for Higher Light Extraction
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Solution Overview
Problem
Existing display apparatuses face challenges in achieving high light output efficiency from their backlight units, particularly in converting the wavelength of light emitted by light emitting diodes to improve brightness and color reproduction.
Innovation Solution
A backlight unit design incorporating a light emitting diode with a refractive layer and a quantum dot layer to manage refractive indices, where the quantum dot layer converts monochromatic light from the diode into white light, enhancing light output efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional backlight unit with a single light source is used, then the structure is simple, but the light output efficiency is insufficient
Solution Approach 1:
The backlight unit is segmented into multiple functional layers: a light source layer with blue LEDs, a quantum dot layer for wavelength conversion, and a refractive layer for light extraction. This segmentation allows each layer to perform its specific function optimally, improving overall light output efficiency while maintaining manageable structural complexity through modular design
Solution Approach 2:
The patent employs composite materials including quantum dots (CdSe, ZnSe) combined with specific resin matrices, and multi-layer refractive index structures. These composite materials enable efficient wavelength conversion and light extraction, significantly improving light output efficiency by converting blue LED light into broad-spectrum white light with enhanced brightness
2Productivity
If the refractive index difference between layers is increased to improve light extraction, then light output efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent systematically varies refractive index parameters across different layers: the light source layer has refractive index 1.8-2.2, the quantum dot layer 1.4-1.7, and the resin matrix 1.3-1.6. This controlled parameter change creates optimal refraction conditions at each interface, improving light extraction efficiency while maintaining manufacturability through well-defined parameter ranges
Solution Approach 2:
Different regions of the backlight unit are assigned different refractive index qualities: higher refractive index materials are used where light generation occurs, while lower refractive index materials are used in conversion and extraction layers. This local quality differentiation optimizes light extraction at critical interfaces without requiring extreme precision across the entire structure
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 design significantly improves light output efficiency by converting monochromatic light into white light, enhancing brightness and color reproduction in the display apparatus.
Implementation Method 1
a quantum dot layer covering the refractive layer, configured to convert a wavelength of light emitted from the light emitting diode
Implementation Method 2
a refractive layer covering the light emitting diode and having a second refractive index, r2, that is lower than the first refractive index
Data Source
AI summary
This display apparatus includes a liquid crystal panel; and a backlight configured to provide light to the liquid crystal panel, wherein the backlight comprises: a substrate; a light emitting diode provided on the substrate, the light emitting diode comprising a light output layer having a first refractive index, r1; a refractive layer covering the light emitting diode and having a second refractive index, r2, that is lower than the first refractive index; and a quantum dot layer covering the refractive layer, configured to convert a wavelength of light emitted from the light emitting diode, the quantum dot layer having a third refractive index, r3, that is lower than the second refractive index.