Backlight Module Cholesteric Liquid Crystal Uniformity
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Solution Overview
Problem
Direct-lit backlight modules using light-emitting diodes suffer from hot spot phenomena due to non-uniform light output, leading to decreased brightness uniformity, and require high assembly accuracy with light-shielding films, increasing production costs.
Innovation Solution
Incorporating a first and second cholesteric liquid-crystal layer with different chiral directions on the light-emitting devices to redirect forward light away from the emitting surface, improving uniformity and reducing assembly complexity compared to traditional light-shielding films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light-shielding films with light-shielding dots are used to solve hot spot phenomenon, then brightness uniformity is improved, but assembly accuracy requirement increases and production cost increases
Solution Approach 1:
The patent replaces the mechanical light-shielding film assembly with an optical solution using cholesteric liquid crystal layers. The liquid crystal layers use optical rotation to redirect light paths, eliminating the need for precise mechanical alignment of light-shielding dots. This substitution of mechanical assembly with optical manipulation resolves the contradiction by improving brightness uniformity without increasing assembly accuracy requirements.
Solution Approach 2:
The patent changes the optical parameters of the light-emitting surface by introducing cholesteric liquid crystal layers with specific helical structures. These layers rotate the polarization state of light and redirect light paths through optical anisotropy, transforming the light distribution pattern without requiring precise mechanical positioning. This parameter change approach improves uniformity while avoiding the assembly accuracy issues of light-shielding films.
2Illumination intensity
If light-shielding films with light-shielding dots are used to solve hot spot phenomenon, then brightness uniformity is improved, but production cost increases
Solution Approach 1:
The patent replaces the costly light-shielding film assembly with cholesteric liquid crystal layers that can be integrated into the display panel manufacturing process. The liquid crystal layers utilize optical properties rather than mechanical light blocking, reducing material costs and eliminating the need for separate assembly steps. This substitution reduces production cost while maintaining brightness uniformity improvement.
Solution Approach 2:
The cholesteric liquid crystal layers serve multiple functions: they improve brightness uniformity by redirecting light paths, maintain local dimming functionality, and can be integrated into the existing display panel structure. This multi-functionality eliminates the need for separate light-shielding film components, reducing overall production cost while achieving the desired uniformity improvement.
3Length of stationary object
If thin direct-lit backlight modules are used, then overall thickness is reduced, but hot spot phenomenon increases
Solution Approach 1:
The patent addresses the hot spot issue in thin backlight modules by introducing a new dimension of optical control through cholesteric liquid crystal layers. These layers manipulate light in the angular and polarization domains, redirecting light paths laterally to compensate for the reduced optical distance. This dimensional approach to light manipulation improves uniformity without increasing the overall thickness of the module.
Solution Approach 2:
The patent changes the optical parameters of the light distribution by introducing cholesteric liquid crystal layers with specific helical pitch and orientation. These layers rotate light polarization and redirect light paths through optical anisotropy, transforming the light distribution pattern. This parameter change enables uniform brightness in thin modules by optically compensating for the reduced distance between light sources and the display surface.
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 light output uniformity and reduces production costs by simplifying the manufacturing process while maintaining the local dimming functionality of the backlight module.
Implementation Method 1
The first cholesteric liquid-crystal layer is disposed on the light-emitting devices and overlapped with a light-emitting surface of each of the light-emitting devices. The second cholesteric liquid-crystal layer is disposed on the first cholesteric liquid-crystal layer and overlapped with the first cholesteric liquid-crystal layer. The first cholesteric liquid-crystal layer and the second cholesteric liquid-crystal layer respectively have a first chiral direction and a second chiral direction.
Data Source
AI summary
A backlight module including a circuit substrate, a plurality of light-emitting devices, a first cholesteric liquid-crystal layer, and a second cholesteric liquid-crystal layer is provided. The light-emitting devices are disposed on the circuit substrate and electrically connected to the circuit substrate. The first cholesteric liquid-crystal layer is disposed on the light-emitting devices and overlapped with a light-emitting surface of each of the light-emitting devices. The second cholesteric liquid-crystal layer is disposed on the first cholesteric liquid-crystal layer and overlapped with the first cholesteric liquid-crystal layer. The first cholesteric liquid-crystal layer and the second cholesteric liquid-crystal layer respectively have a first chiral direction and a second chiral direction. A display apparatus adopting the backlight module is also provided.