Backlight Unit Wavelength Conversion Light Scattering Brightness
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Solution Overview
Problem
Existing liquid crystal display devices with backlight units using wavelength conversion members struggle to achieve optimal brightness due to limitations in light scattering and absorption efficiency, leading to reduced image quality and increased material usage.
Innovation Solution
A backlight unit incorporating a wavelength conversion member with a light scattering layer containing particles greater than or equal to 0.1 μm in a matrix, where the average refractive index of the wavelength conversion layer is less than that of the matrix, and a light absorptivity of the light scattering layer is less than or equal to 8.0%, enhancing light scattering and emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If particles are arranged in a portion separated from the wavelength conversion layer to scatter light, then light scattering function is improved, but device complexity increases
Solution Approach 1:
The patent combines the light scattering function with the wavelength conversion layer by incorporating scattering particles directly into the wavelength conversion layer. This integration eliminates the need for a separate light scattering layer, reducing device complexity while maintaining the light scattering function that improves brightness.
Solution Approach 2:
The wavelength conversion layer is designed to serve multiple functions simultaneously: wavelength conversion and light scattering. By making the wavelength conversion layer multi-functional, the patent reduces the number of separate components needed, thereby simplifying the device structure while achieving the desired brightness improvement.
2Illumination intensity
If fluorescent material amount is increased to improve brightness, then illumination intensity improves, but manufacturing cost increases
Solution Approach 1:
The patent introduces light scattering particles as an intermediary element that enhances the efficiency of the fluorescent material. These particles increase the path length of light through the wavelength conversion layer, improving the excitation of fluorescent material and light extraction efficiency. This allows achieving the desired brightness with less fluorescent material, thereby reducing manufacturing cost.
Solution Approach 2:
The patent optimizes the refractive index parameters of the wavelength conversion layer and scattering particles to maximize light scattering and extraction efficiency. By carefully controlling these optical parameters, the system achieves higher brightness with reduced fluorescent material content, addressing the cost issue.
3Illumination intensity
If wavelength conversion layer thickness is increased to improve brightness, then illumination intensity improves, but device thickness increases
Solution Approach 1:
The patent uses light scattering particles to create optical path variations within the wavelength conversion layer, effectively increasing the light-matter interaction path length without increasing the physical thickness of the layer. This allows achieving sufficient brightness in a thinner backlight unit.
Solution Approach 2:
The patent optimizes the refractive index contrast between the wavelength conversion layer and surrounding layers to enhance light extraction efficiency. By adjusting these optical parameters, the system achieves higher brightness in a thinner configuration, addressing the thickness constraint.
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 significantly improves the brightness of liquid crystal display devices by increasing light emission efficiency and reducing material usage, resulting in a more vivid and cost-effective image display.
Implementation Method 1
a light scattering layer containing particles having a particle size of greater than or equal to 0.1 μm in a matrix
Implementation Method 2
a wavelength conversion layer containing a fluorescent material which is excited by exciting light and emits fluorescent light
Data Source
AI summary
Provided is a backlight unit, including: a light source allowing light having a light emission center wavelength of λ nm to exit; and a wavelength conversion member positioned on an optical path of the light exiting from the light source, in which the wavelength conversion member includes a wavelength conversion layer containing a fluorescent material which is excited by exciting light and emits fluorescent light, and a light scattering layer containing particles having a particle size of greater than or equal to 0.1 μm in a matrix, an average refractive index n1 of the wavelength conversion layer satisfies a relationship of n1<n2 with respect to an average refractive index n2 of the matrix of the light scattering layer, and a light absorptivity of the light scattering layer at a wavelength of λ nm is less than or equal to 8.0%.