Wavelength Conversion Layer Light Extraction for Display Brightness
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Solution Overview
Problem
Current liquid crystal display devices using fluorescent materials face low external quantum efficiency due to isotropic fluorescence propagation and decreased aperture ratio in wavelength conversion layers, requiring a structure to improve light extraction without collimated backlights.
Innovation Solution
A display device with a wavelength conversion layer on each pixel, a light scattering layer between them, and a reflection layer on both sides, featuring fine particles with varying concentrations and refractive indices to redirect fluorescence forward, and a grid-shaped reflection layer for pixel division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a light extraction structure is used to improve external quantum efficiency, then fluorescence direction is improved, but the aperture ratio of the wavelength conversion layer is decreased
Solution Approach 1:
The patent divides the wavelength conversion layer into multiple segments corresponding to different pixels, with each segment having its own light extraction structure. This segmentation allows light extraction functionality to be added without significantly reducing the overall aperture ratio, as the light extraction structures are integrated within the pixel boundaries rather than occupying additional space.
Solution Approach 2:
The patent introduces light extraction structures that operate in the vertical dimension (thickness direction) rather than only in the planar dimension. By using vertical micro-lenses, prisms, or roughened surfaces on the upper surface of the wavelength conversion layer, the patent extracts light in the forward direction without reducing the planar aperture ratio of the wavelength conversion layer.
2Loss of energy
If a collimated backlight source is used to excite the wavelength conversion layer, then fluorescence extraction is improved, but the efficiency of the backlight source is decreased
Solution Approach 1:
The patent introduces an intermediate light extraction structure (such as micro-lenses, prisms, or roughened surfaces) between the wavelength conversion layer and the observer. This intermediary structure redirects isotropically emitted fluorescence into the forward direction without requiring the backlight source to be collimated, thus maintaining backlight efficiency while improving fluorescence extraction.
Solution Approach 2:
The wavelength conversion layer itself generates the light extraction functionality through its own structural features (such as integrated micro-lenses or prisms formed during the same manufacturing process). This self-service approach eliminates the need for separate collimated backlight systems, maintaining backlight efficiency while achieving effective light extraction.
3Adaptability or versatility
If fluorescent materials are used for wavelength conversion, then color display capability is improved, but external quantum efficiency is decreased due to isotropic fluorescence propagation
Solution Approach 1:
The patent applies different structural features to different regions of the wavelength conversion layer to optimize light extraction. For example, different pixel regions may have different micro-lens configurations, prism orientations, or surface roughness patterns tailored to their specific color requirements and viewing angle needs, thereby maintaining color display capability while improving external quantum efficiency.
Solution Approach 2:
The patent uses composite structures combining the wavelength conversion layer with integrated light extraction features (such as micro-lens arrays, prism structures, or roughened surfaces) formed in the same layer or as separate integrated layers. This composite approach enables simultaneous achievement of color conversion and directional light extraction without compromising external quantum 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
Enhances external quantum efficiency and energy efficiency, resulting in improved brightness and longer battery life for high-definition displays.
Implementation Method 1
a light scattering layer between the wavelength conversion layers; the light scattering layers have fine particles
Implementation Method 2
a reflection layer is provided on the wavelength conversion layers on the backlight side; and a reflection layer is provided on the light scattering layers on the display surface side
Implementation Method 3
blue light sources or near-ultraviolet light sources are used for light sources, and source light beams are absorbed by a wavelength conversion layer to emit fluorescence
Data Source
AI summary
The present invention realizes a high-definition and high-brightness display device with a high degree of energy efficiency. The above-described object can be realized by a display device including a display panel having a display surface and a backlight, wherein: the display panel has a wavelength conversion layer for each pixel on a surface parallel to the display surface, and has a light scattering layer between the wavelength conversion layers; the wavelength conversion layers have fluorescent materials; the light scattering layers have fine particles; a reflection layer is provided on the wavelength conversion layers on the backlight side; and a reflection layer is provided on the light scattering layers on the display surface side.