Optical Laminate Bonding Structure for Polarizer Shrinkage Stress
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Solution Overview
Problem
Existing variable transmittance optical stacks with stretched polarizers suffer from residual stress leading to sealant adhesion issues, dimensional changes, and liquid crystal leakage due to temperature fluctuations.
Innovation Solution
A variable transmittance optical stack design incorporating pressure-sensitive adhesive bonding layers to control the shrinkage force of stretched polarizers, minimizing damage to sealants and bubbles, and reducing dimensional changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a stretched polarizer is used in the variable transmittance optical stack, then the manufacturing cost is reduced and the manufacturing process is simplified, but residual stress remains in the polarizer causing sealant adhesion damage and liquid crystal leakage
Solution Approach 1:
A release film is introduced as an intermediary layer between the stretched polarizer and the sealant. This release film absorbs the residual stress from the stretched polarizer during temperature changes, preventing the stress from being transmitted to the sealant and causing adhesion failure. The release film acts as a buffer that mediates the stress interaction between the polarizer and sealant.
Solution Approach 2:
The invention changes the physical parameters of the polarizer assembly by controlling the stretching degree and introducing a release film with specific mechanical properties. By adjusting these parameters, the residual stress in the stretched polarizer is managed to prevent sealant damage while maintaining the manufacturing advantages of using stretched polarizers.
2Reliability
If the shrinkage force of the stretched polarizer is increased to maintain adhesion, then sealant adhesion is improved, but dimensional changes in the optical stack increase
Solution Approach 1:
The release film serves as a mediator that decouples the shrinkage force of the stretched polarizer from the sealant. This allows the polarizer to exert its full shrinkage force without directly pulling on the sealant, thereby maintaining adhesion while preventing excessive dimensional changes in the overall optical stack structure.
Solution Approach 2:
The invention segments the stress transmission path by inserting a release film between the stretched polarizer and the sealant. This segmentation allows the shrinkage force to be contained within the polarizer-release film system without being transmitted to the sealant and causing dimensional instability in the optical stack.
3Adaptability or versatility
If external temperature changes are applied to the stretched polarizer, then the variable transmittance function is activated, but the polarizer shrinks or deforms causing liquid crystal leakage
Solution Approach 1:
The release film is installed beforehand to cushion and absorb the shrinkage stress that will occur when temperature changes activate the variable transmittance function. This prior cushioning prevents the polarizer's shrinkage from deforming the sealant and causing liquid crystal leakage during normal operation.
Solution Approach 2:
The release film acts as a protective intermediary between the temperature-responsive stretched polarizer and the liquid crystal containment system. When temperature changes cause the polarizer to shrink, the release film absorbs this mechanical stress, preventing it from transmitting to the sealant and maintaining liquid crystal containment integrity.
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 solution effectively maintains sealant adhesion and minimizes dimensional changes and bubble ingress in temperature-changing environments, ensuring stable optical performance.
Implementation Method 1
at least one of the first bonding layer and the second bonding layer may be formed of a pressure-sensitive adhesive
Implementation Method 2
stress generated during the stretching process remains in the polarizer. Thus, when external stimulation is continuously applied to the stretched polarizer, the polarizer cannot withstand the residual stress and shrinks or deforms
Implementation Method 3
The variable transmittance optical stack is driven by changing the transmittance by driving liquid crystal according to voltage application
Data Source
AI summary
The present invention relates to a variable transmittance optical laminate comprising: a first transparent member; a first laminate which is formed on the first transparent member, and on which a first polarizing plate, a first transparent conductive layer, and a first alignment layer are sequentially stacked; a second transparent member facing the first transparent member; a second laminate which is formed on the second transparent member, and on which a second polarizing plate, a second transparent conductive layer, and a second alignment layer are sequentially stacked; and a liquid crystal layer disposed between the first laminate and the second laminate. At least one of the first transparent conductive layer and the second transparent conductive layer is formed in direct contact with any one of the first polarizing plate and the second polarizing plate, the first transparent member and the first polarizing plate are bonded by means of a first bonding layer, the second transparent member and the second polarizing plate are bonded by means of a second bonding layer, and at least one of the first bonding layer and the second bonding layer is formed of an adhesive.