Smart Window Lamination With Staged Pressure to Prevent LC Mura
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Solution Overview
Problem
Conventional smart windows with fixed transmittance cause issues such as difficulty in visibility at night or glare during the day due to fixed light blocking, and the manufacturing process of transmittance variable optical laminates leads to uneven distribution of liquid crystals, resulting in liquid crystal mura.
Innovation Solution
A method for manufacturing smart windows involving a two-step bonding process at different pressures to minimize pressure on the liquid crystal layer, incorporating a gap and surface protective layers to prevent mura, and eliminating the need for a separate substrate for the conductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-step bonding process is used to bond substrate to film laminate, then manufacturing efficiency is improved, but uneven pressure is applied to liquid crystal layer causing liquid crystal mura
Solution Approach 1:
The bonding process is divided into multiple sequential steps with different pressure levels. The first step applies higher pressure (3-10 bar) for initial bonding, while subsequent steps apply lower pressure (0.5-3 bar) to complete bonding without causing liquid crystal mura. This segmentation resolves the contradiction by achieving both efficiency and precision through staged pressure application.
2Stability of the object's composition
If optical laminate includes separate substrate for conductive layer, then structural stability is improved, but overall thickness increases
Solution Approach 1:
The conductive layer is integrated directly onto the substrate surface, eliminating the need for a separate conductive layer substrate. This merging of functions reduces the overall optical laminate thickness while maintaining structural stability through the adhesive layer and protective layers that ensure proper bonding and protection.
3Strength
If glass bonding pressure is applied during manufacturing, then bonding strength is improved, but liquid crystal layer becomes unevenly distributed causing mura
Solution Approach 1:
The bonding process uses dynamic pressure adjustment with multiple steps rather than static single-step pressure. The pressure is dynamically reduced from higher initial pressure to lower final pressure, allowing strong bonding to be achieved while preventing liquid crystal mura through adaptive pressure control.
4Illumination intensity
If transmittance is set high for daytime visibility, then light transmission is improved, but glare occurs during day when ambient light is sufficient
Solution Approach 1:
The optical laminate enables dynamic control of light transmittance through liquid crystal switching. The transmittance can be adjusted from high (for nighttime visibility) to low (for daytime glare prevention), providing adaptive optical properties that eliminate the need to choose between visibility and glare protection.
5Object-affected harmful factors
If transmittance is set low for nighttime visibility, then external light blocking is improved, but driver cannot properly check surroundings at night when ambient light is insufficient
Solution Approach 1:
The system provides dynamic transmittance control that can be adjusted based on ambient lighting conditions. At nighttime, high transmittance allows proper visibility of surroundings, while the ability to reduce transmittance when needed provides external light blocking capability.
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 method produces high-quality smart windows with reduced thickness and no liquid crystal mura, suitable for various applications including vehicles and buildings, by gradually bonding the laminate components to evenly distribute pressure.
Implementation Method 1
a transmittance variable optical laminate capable of changing the transmittance of light when a voltage is applied has been developed. The transmittance variable optical laminate is driven to change transmittance by driving liquid crystals in response to application of a voltage.
Implementation Method 2
a main bonding step of bonding the substrate to the film laminate, wherein the main bonding step includes: step a) of maintaining a laminate resulting from the pre-bonding step at a pressure of 3.5 to 10 bar for 15 to 60 minutes; and step b) of maintaining a laminate resulting from step a) at a reduced pressure of 1 bar to 3 bar for 70 to 100 minutes
Data Source
Figure 1~2a
Figure 2b~3
Figure 4a~4b
AI summary
Disclosed are a method for manufacturing a smart window and a smart window manufactured thereby. The method includes: a step of laminating a film laminate including an optical laminate, an adhesive layer, and a substrate; a pre-bonding step; and a main bonding step, wherein the main bonding step includes: step a) of maintaining a laminate resulting from the pre-bonding step at a pressure of 3.5 to 10 bar for 15 to 60 minutes; and step b) of maintaining a laminate resulting from step a) at a reduced pressure of 1 bar to 3 bar for 70 to 100 minutes. According to the disclosure, the unevenness of the pressure applied to the liquid crystal layer during glass bonding may be eliminated, thereby manufacturing a smart window in which the uneven distribution of liquid crystals does not occur.