Smart Window Optical Stack With Direct Conductive Layer and Spacer Control
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Solution Overview
Problem
Conventional variable transmittance optical stacks face issues with increased manufacturing complexity, thickness, and reduced transmittance due to the inclusion of a separate substrate for forming a conductive layer, leading to cracks, scratches, and spacer reliability problems.
Innovation Solution
A variable transmittance optical stack design that eliminates the need for a separate substrate by directly forming the conductive layer on a polarizing plate, incorporating a functional coating layer for hardness, optimizing ball spacer quantity, and using an adhesion-imparting layer for improved spacer reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate substrate is included to form the conductive layer, then the conductive layer can be formed, but the manufacturing process becomes complicated and manufacturing costs increase
Solution Approach 1:
The patent combines the substrate and conductive layer into a single integrated structure. The transparent substrate itself serves as the base for the conductive layer, eliminating the need for a separate substrate. This merging reduces manufacturing complexity while maintaining the functional integrity of the conductive layer.
Solution Approach 2:
The transparent substrate is designed to serve multiple functions: it provides mechanical support, optical transparency, and serves as the foundation for the conductive layer. This multi-functionality eliminates the need for additional dedicated substrates, simplifying the overall structure and manufacturing process.
2Reliability
If a separate substrate is included to form the conductive layer, then the conductive layer can be formed, but the thickness of the stack is increased
Solution Approach 1:
By merging the substrate and conductive layer functions into a single integrated component, the patent eliminates the additional thickness that would result from stacking separate substrates. The conductive layer is formed directly on the transparent substrate, minimizing the overall stack thickness.
3Reliability
If a separate substrate is included to form the conductive layer, then the conductive layer can be formed, but transmittance is changed due to the occurrence of retardation
Solution Approach 1:
The integration of the conductive layer directly on the transparent substrate eliminates additional optical interfaces that cause retardation effects. This merging reduces optical interference and maintains high light transmittance while ensuring reliable conductive layer formation.
4Ease of manufacture
If pressure is applied by spacers in the bonding process, then bonding can be achieved, but cracks occur in the conductive layer
Solution Approach 1:
By combining the substrate and conductive layer into a single integrated structure, the patent creates a more robust configuration that better withstands bonding pressure. The integrated structure distributes stress more effectively, preventing cracks that would otherwise occur in separate layered configurations during the bonding process.
5Device complexity
If the conductive layer is formed directly on the polarizing plate, then the manufacturing process is simplified, but the surface hardness may be reduced
Solution Approach 1:
The patent employs composite material structures where the transparent substrate is combined with hardened coating layers. This composite approach maintains manufacturing simplicity while restoring surface hardness through the addition of durable coating materials that protect the underlying conductive structures.
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 simplifies the manufacturing process, reduces thickness, enhances transmittance, minimizes cracks and scratches, and improves spacer reliability, while maintaining optimal spacer distribution.
Implementation Method 1
a variable transmittance optical stack capable of changing the transmittance of light when a voltage is applied has been developed
Data Source
AI summary
The present invention relates to a variable transmittance optical stack structure, a manufacturing method therefor, and a smart window comprising same, the variable transmittance optical stack structure comprising: a first stack structure in which a first polarization plate including a first functional coating layer, a first transparent conductive layer, and a first alignment layer are sequentially stacked; a second stack structure in which a second polarization plate including a second functional coating layer, a second transparent conductive layer, and a second alignment layer are sequentially stacked; and a liquid crystal layer, wherein the liquid crystal layer includes ball spacers having a diameter of 4 to 10 μm and provided via an adhesion-imparting layer formed on any one alignment layer, and at least one transparent conductive layer is formed in direct contact with any one polarization plate, and the first and second functional coating layers each have a Vickers hardness of 18 to 41, and the number of ball spacers per unit area with respect to the diameter of the ball spacers satisfies a predetermined relationship.