Brightness Homogenizing Member for LCD Backlight Uniformity
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in achieving uniform in-plane brightness due to the directivity of LED light sources, leading to noticeable brightness unevenness, which complicates the thinning of the backlight unit and the overall display device.
Innovation Solution
A brightness homogenizing member with a lamination structure of high and low refractive index layers, where light bending portions on the emission surface redirect light to increase its in-plane component, improving brightness uniformity by scattering light at various angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the distance between the light diffusion plate and the LED light source is increased to reduce brightness unevenness, then the in-plane brightness uniformity is improved, but the thickness of the backlight unit increases
Solution Approach 1:
The light diffusion plate is segmented into multiple layers with different refractive indices (high refractive index layers and low refractive index layers alternately laminated). This segmentation allows each layer to contribute differently to light diffusion, achieving effective brightness homogenization in a compact thickness by distributing the diffusion function across multiple thin layers rather than requiring a single thick plate or large separation distance.
Solution Approach 2:
The invention uses composite material structure by alternately laminating layers of high refractive index and low refractive index materials. This composite structure creates multiple interfaces that scatter and redirect light, enhancing the diffusion effect within a thin profile. The combination of materials with different optical properties enables effective brightness uniformity without increasing overall thickness.
2Ease of manufacture
If a light diffusion plate with scattering particles is used to diffuse light, then light scattering occurs at various angles, but the brightness remains high at the light source position and decreases with distance, resulting in low in-plane brightness uniformity
Solution Approach 1:
Instead of using a single homogeneous diffusion layer, the invention segments the diffusion function across multiple layers with alternating refractive indices. Each layer contributes to light scattering and redirection, creating a cumulative diffusion effect that achieves uniform in-plane brightness while maintaining ease of manufacture through modular layer construction.
Solution Approach 2:
The invention changes the optical parameter (refractive index) by alternating between high and low refractive index layers. This parameter variation creates multiple refraction and reflection interfaces that enhance light scattering efficiency, improving in-plane brightness uniformity while maintaining a compact structure that is easy to manufacture.
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 effectively enhances in-plane brightness uniformity, allowing for a reduction in the thickness of the backlight unit and the liquid crystal display device while maintaining even light distribution.
Implementation Method 1
the brightness homogenizing member has a lamination structure in which layers of high refractive index having a relatively high refractive index and layers of low refractive index having a relatively low refractive index are alternately laminated
Implementation Method 2
each of a plurality of the layers of high refractive index includes, on a surface on an emission surface side, a light bending portion that bends at least a portion of light proceeding in a direction intersecting the emission surface and causes the light to proceed in a direction in which an in-plane component parallel to the emission surface increases
Data Source
AI summary
A brightness homogenizing member comprising: an incidence surface and an emission surface, the brightness homogenizing member has a lamination structure in which the brightness homogenizing member has a layer of high refractive index and a layer of low refractive index are alternately laminated in a direction perpendicular to the emission surface, each of a plurality of the layers of high refractive index includes, on a light emission surface side, a light bending portion that bends at least a portion of light proceeding in a direction intersecting to the emission surface and cause the light to proceed in a direction in which an in-plane component parallel to the emission surface increases, in a case where the lamination structure is planarly viewed from a lamination direction in the lamination structure, the light bending portions are provided in different positions between the plurality of the layers of high refractive index.