Smart Window Optical Stack With Film-Free Liquid Crystal Alignment
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Solution Overview
Problem
Conventional variable transmittance optical stacks for smart windows face issues with thickness unevenness and deteriorated adhesion due to the use of alignment films, which can lead to product defects and suboptimal performance.
Innovation Solution
A variable transmittance optical stack design that eliminates the need for a separate alignment film by incorporating conductive polymers in electrode layers with physical alignment structures, directly formed on polarizing plates, and includes transparent conductive layers and functional layers to enhance adhesion and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an alignment film is used to provide orientation of liquid crystal compounds, then the liquid crystal orientation is improved, but thickness unevenness and deteriorated adhesion occur due to drying conditions
Solution Approach 1:
The patent combines the alignment function and electrode function into a single integrated layer. The ITO layer is subjected to plasma treatment and rubbing to create both electrical conductivity and liquid crystal alignment properties, eliminating the need for a separate alignment film and thus avoiding adhesion issues while maintaining orientation precision.
Solution Approach 2:
The ITO electrode layer is given multiple functions: it serves as both the electrical conductor and the alignment layer for liquid crystals. Through plasma treatment and rubbing, the ITO layer acquires alignment properties in addition to its inherent conductivity, making it a multi-functional component that resolves the contradiction between orientation precision and adhesion reliability.
2Manufacturing precision
If an alignment film is used to provide orientation of liquid crystal compounds, then the liquid crystal orientation is improved, but plasma processing damages the substrate
Solution Approach 1:
The patent merges the alignment function into the electrode layer itself, so that plasma treatment is applied to the ITO layer rather than a separate alignment film. This integration reduces the number of plasma processing steps and protects the substrate from repeated plasma exposure while still achieving precise liquid crystal orientation.
3Manufacturing precision
If a separate alignment film is included, then liquid crystal orientation is achieved, but the device complexity increases
Solution Approach 1:
The patent merges two separate components (alignment film and electrode layer) into a single integrated ITO layer. This reduces the total number of layers and simplifies the manufacturing process while maintaining the alignment function, directly addressing the complexity issue.
Solution Approach 2:
The ITO electrode layer is designed to perform multiple functions simultaneously: electrical conduction and liquid crystal alignment. This multi-functionality eliminates the need for separate alignment film components, thereby reducing device complexity while preserving orientation precision.
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
This design prevents defects related to alignment film issues, ensures stable operation with reduced thickness and improved curvature characteristics, and maintains high transmittance and optical quality, making it suitable for smart windows in vehicles and buildings.
Implementation Method 1
the first electrode layer and the second electrode layer may have physical alignment structures on at least a part of regions thereof by a rubbing manner
Implementation Method 2
a variable transmittance optical stack capable of changing transmissive properties of light when a voltage is applied has been developed. The variable transmittance optical stack is driven by changing the transmittance by controlling liquid crystals according to application of voltage
Data Source
Figure 1~2
Figure 3~4B
Figure 4C~4E
AI summary
A variable transmittance optical stack and a manufacturing method for the same, and a smart window including the same are proposed, and the variable transmittance optical stack includes a first polarizing plate, a first electrode layer formed on one surface of the first polarizing plate, a second polarizing plate opposing the first polarizing plate, a second electrode layer formed on one surface of the second polarizing plate, and opposing the first electrode layer, and a liquid crystal layer provided between the first electrode layer and the second electrode layer, wherein the first electrode layer and the second electrode layer includes conductive polymers, and the first electrode layer and the second electrode layer have physical alignment structures on at least a part of regions thereof by a rubbing manner.