Quantum Dot Color Filter for LCD Blue Light Excitation
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Solution Overview
Problem
Existing LCD display screens face challenges with narrow color gamut and low optical efficiency due to the use of traditional backlight sources, which result in impure color rendering and low brightness.
Innovation Solution
The implementation of a blue light backlight source combined with quantum dot material thin film patterns in the color filter layer, where red and green pixel patterns emit light under blue excitation, enhancing color gamut and optical efficiency while omitting the need for a blue pixel layer and simplifying the manufacturing process by using inorganic quantum dot materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a white backlight is formed by mixing yellow and blue light using a YAG fluorescent powder, then the backlight can be generated, but the light emitting efficiency is low, the color is impure, and the color gamut is relatively low
Solution Approach 1:
The patent changes the excitation wavelength parameter from broad-spectrum white light to specific blue light (430-470nm), and changes the fluorescent material from YAG to quantum dots with specific size parameters (2-5nm for green, 6-10nm for red), achieving narrow emission spectra and high color gamut while maintaining high light emitting efficiency
Solution Approach 2:
The patent uses composite quantum dot structures (CdSe/ZnS core-shell) combining different materials with specific properties: CdSe for light emission and ZnS for protection and efficiency enhancement, achieving both high color gamut and high light emitting efficiency simultaneously
2Loss of energy
If quantum dot materials are applied to a backlight source, then the light emitting efficiency is improved, but the color gamut and optical efficiency cannot be maximized
Solution Approach 1:
The patent applies different quantum dot sizes (2-5nm for green emission, 6-10nm for red emission) to different pixel regions, with each region having locally optimized quantum dot characteristics matched to its specific color requirements, achieving maximum color gamut and optical efficiency for each pixel type
Solution Approach 2:
The patent introduces a blue light filter layer as an intermediary component with specific optical properties (transmission rate T≥85% at 430-470nm) to purify the blue light excitation source, ensuring that only the appropriate wavelength range reaches the quantum dots, thereby maximizing both efficiency and color gamut
3Device complexity
If traditional color filter layers are used with all three primary colors, then complete color coverage is achieved, but the manufacturing process is complex and the aperture ratio is reduced
Solution Approach 1:
The patent extracts and removes the blue pixel layer from the color filter structure, relying instead on quantum dots to generate blue light through blue light excitation, thereby simplifying the manufacturing process and increasing the aperture ratio while maintaining complete color coverage
Solution Approach 2:
The patent makes the quantum dot layer multi-functional by enabling it to generate all three primary colors (red, green, and blue) through a single blue light excitation source, eliminating the need for separate color filter layers for each pixel and simplifying the overall device 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
This approach results in a display device with a wider color gamut and higher optical efficiency, reduced manufacturing costs, and improved stability due to the use of inorganic quantum dot materials, along with increased aperture ratio and monochromaticity through the application of a blue light filter layer.
Implementation Method 1
The quantum dot is generally nano particles composed of II-VI group or III-V group elements, and can emit fluorescent light after being excited
Implementation Method 2
increased aperture ratio and monochromaticity through the application of a blue light filter layer
Data Source
Figure 1~2
Figure 3~4
AI summary
A liquid crystal display device and a method of manufacturing it are provided. The display device includes a blue light backlight source (1) and a liquid crystal display panel (2), wherein the liquid crystal display panel comprises a first substrate (22) and a second substrate (21). The first substrate or the second substrate includes a layered assembly, functioning as a colour filter and including a black matrix pattern (201), a red pixel pattern (202) and a green pixel pattern (203), wherein the red pixel pattern and the green pixel pattern are quantum dot material thin-film patterns respectively emitting red light and green light upon excitation by blue light. The red pixel pattern (202) is separated from the black matrix pattern (201) by an intervening first passivation layer (241); furthermore, the red and green pixel patterns are mutually separated by an intervening second passivation layer (242), and the green pixel pattern (203) is covered by a protection layer (243).