Light Guide Plate Two-Layer Scattering Structure
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Solution Overview
Problem
Large-sized edge-lit backlight units for liquid crystal displays face challenges in reducing color unevenness and luminance inconsistencies due to varying light scattering efficiency across different wavelengths, leading to increased costs and manufacturing complexities, especially when trying to achieve a convex brightness distribution for larger flat screens.
Innovation Solution
A light guide plate with a two-layer structure, where one layer has a higher scattering particle concentration than the other, and the particle size distribution includes local maximum values below and above 7 μm, with specific ratios and configurations to optimize light scattering and distribution, ensuring uniform light emission across the screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If scattering particles are dispersed inside the light guide plate to scatter light, then light scattering ability is improved, but color unevenness increases due to wavelength-dependent scattering efficiency
Solution Approach 1:
The patent applies local quality by using scattering particles with different particle sizes (first particle size larger than 7μm, second particle size smaller than 7μm) distributed in different regions of the light guide plate. This creates spatially varying scattering characteristics that compensate for the wavelength-dependent scattering effect, thereby reducing color unevenness while maintaining overall light scattering ability.
Solution Approach 2:
The patent uses a composite scattering particle system combining two types of particles with different size characteristics. The first particles (larger than 7μm) and second particles (smaller than 7μm) work together to achieve broadband scattering performance that reduces wavelength-dependent color variation while maintaining effective light diffusion throughout the light guide plate.
2Area of stationary object
If light is guided over longer distances in large-sized backlight units, then screen size is increased, but color unevenness and luminance inconsistencies worsen
Solution Approach 1:
The patent implements local quality by strategically distributing different particle size types in different longitudinal positions within the light guide plate. The first particles (larger than 7μm) and second particles (smaller than 7μm) are arranged to create region-specific scattering characteristics that maintain luminance and color uniformity across extended distances, enabling large screen sizes without sacrificing optical uniformity.
Solution Approach 2:
The patent applies parameter changes by varying the particle size distribution parameter along the light propagation direction. By controlling the ratio and spatial arrangement of particles with different size parameters (greater than 7μm versus smaller than 7μm), the optical properties are dynamically adjusted to maintain uniform light output across large areas.
3Use of energy by moving object
If scattering particle concentration is increased to improve light diffusion, then light use efficiency improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent reduces manufacturing complexity by applying local quality in a simplified manner: dividing the light guide plate into two particle size groups (larger than 7μm and smaller than 7μm) with controlled ratios. This binary classification system is easier to implement than continuous particle size distribution control, thereby reducing manufacturing complexity while maintaining high light use efficiency through optimized scattering.
Solution Approach 2:
The patent simplifies manufacturing by changing the particle size parameter into discrete categories (greater than 7μm versus smaller than 7μm) rather than requiring precise continuous control. This parameter discretization approach maintains effective light scattering and diffusion while significantly reducing the complexity of particle selection and mixing processes.
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 solution provides a high light use efficiency, reduces color and luminance unevenness, and achieves a convex brightness distribution, making it suitable for large flat screens while minimizing manufacturing costs and complexity.
Implementation Method 1
a light guide plate in plate form which is obtained by kneading and dispersing scattering particles for light scattering inside in order to guide the light incident from the lateral surface (light incidence surface) toward the front surface side (light exit surface)
Data Source
AI summary
A large-sized thin light guide plate has a first layer on a light exit surface side and a second layer on a rear surface side containing scattering particles at a higher particle concentration than the first layer. Thicknesses of the layers in a direction substantially perpendicular to the light exit surface change to change a combined particle concentration. The scattering particles, obtained by mixing a particle group with an average particle size Ds of less than 7 μm having one or more local maximum values and a particle group with an average particle size Db of more than 7 μm having one or more local maximum values, satisfy 1 μm≦Ds<7 μm, 7 μm<Db≦12 μm and 0.3≦a≦0.5. High light use efficiency, reduction of luminance and color unevenness, a convex brightness distribution and easy manufacture can be achieved.