Liquid Crystal Display Polymer Network Refractive Index Matching
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Solution Overview
Problem
Conventional liquid crystal display devices operating in transmissive and scattering modes lack the ability to function as a smart window, requiring separate modes based on voltage application, and suffer from reduced brightness due to the refractive index differences between liquid crystal molecules and polymer networks.
Innovation Solution
A liquid crystal display device with a polymer network and liquid crystal molecules that operates in a transmissive mode without an electric field and switches to a scattering mode when a voltage is applied, utilizing alignment layers to control the refractive indices of liquid crystal molecules, allowing for transparency and efficient light scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a liquid crystal layer is disposed between two polarization layers in TN or STN type devices, then the liquid crystal display device can operate in transmissive and scattering modes, but light efficiency decreases and image brightness is reduced
Solution Approach 1:
The patent changes the refractive index parameter of the polymer network to match that of the liquid crystal molecules (both Ne and No values are substantially equal to the polymer refractive index). This parameter matching eliminates light scattering at the liquid crystal-polymer interface, thereby improving light efficiency and image brightness while maintaining the ability to operate in both transmissive and scattering modes through voltage control
2Illumination intensity
If conventional liquid crystal display devices operate in transmissive mode without voltage, then the device is transparent, but it cannot function as a smart window that switches between transparent and display modes
Solution Approach 1:
The patent creates a dynamic system where the liquid crystal molecules can change their orientation state in response to applied voltage. In the off-state (no voltage), molecules are randomly oriented providing transparency. In the on-state (voltage applied), molecules align to create scattering effect for display mode. This dynamic switching capability enables smart window functionality while maintaining high transparency in the off-state due to refractive index matching
3Stability of the object's composition
If the refractive index of liquid crystal molecules differs from the polymer network, then the liquid crystal structure can be formed, but light scattering increases and transparency decreases
Solution Approach 1:
The patent specifically selects and formulates the polymer network with refractive index parameters (Ne and No substantially equal to polymer refractive index) that match the liquid crystal molecules. This parameter optimization allows the liquid crystal structure to be formed and stabilized within the polymer network while minimizing light scattering, thereby maintaining high transparency in the off-state
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
Enables the device to function as a transparent window without voltage and display mode with voltage application, reducing power consumption and maintaining high transparency, while eliminating the need for additional separating members.
Implementation Method 1
an effective refractive index of each liquid crystal molecule in a minor axis and a major axis may be substantially greater than a refractive index of the polymer network when the liquid crystal display device operates in the scattering mode
Implementation Method 2
Each of the first and the second alignment layers may be subject to a rubbing process to align the liquid crystal molecules in a direction substantially parallel to the first substrate or the second substrate
Data Source
AI summary
A liquid crystal display device includes a first substrate, a first electrode on the first substrate, a second substrate facing the first substrate, a second electrode on the second substrate facing the first electrode, and a liquid crystal structure between the first electrode and the second electrode. The liquid crystal structure includes a polymer network and liquid crystal molecules. The liquid crystal display device operates in a transmissive mode when an electric field is not generated between the first and the second electrodes, and operates in a scattering mode when the electric field is generated between the first and the second electrodes.