Curved Liquid-Crystal Cell Arcuately-Bonded Stress Reduction

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Solution Overview

Problem

Existing liquid-crystal cells face challenges when bent into an arcuate shape, as they develop internal stress leading to potential breakage and delamination due to differential tensile, compressive, and shear forces, especially when glass substrates are used.

Innovation Solution

The method involves creating curved, arcuately-bonded liquid-crystal cells where the substrates are bent into a congruently curved configuration before being bonded with an edge adhesive, reducing internal stress by avoiding the bonding process in the flat state, and using photocurable adhesives to secure the substrates in their curved form.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If glass substrates are bent into an arcuate shape and then bonded with edge adhesive, then the liquid-crystal cell achieves a curved configuration, but internal stress develops leading to breakage and delamination

Engineering Contradiction:
Improvecurved configurationVSAvoidresistance to breakage and delamination
Core Design Contradiction:
ShapeVSReliability

Solution Approach 1:

The substrates are pre-bent into the desired congruently curved configuration before the bonding process. This preliminary action ensures that the substrates are already in their final curved shape when bonded, eliminating subsequent stress development from bending after bonding that would cause breakage and delamination.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The conventional sequence is inverted: instead of bonding substrates in a flat state and then bending them into a curved shape, the substrates are first bent into the curved configuration and then bonded. This reversal of the process sequence prevents the development of internal stress that occurs when bonding flat substrates and subsequently forcing them into curvature.

Inventive Principle:
Principle #13The other way round (Inversion)

2Ease of manufacture

If substrates are bonded in a flat state and then bent into a curved configuration, then the bonding process is simpler, but differential tensile, compressive, and shear forces cause internal stress and potential failure

Engineering Contradiction:
Improvebonding process simplicityVSAvoidstructural integrity when curved
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The substrates are pre-shaped into the desired curved configuration before bonding. This preliminary action ensures that the bonding operation is performed on already-curved substrates, eliminating the need for complex post-bonding bending operations and the associated stress development.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The physical state of the substrates is changed from flat to curved before the bonding process. This parameter change ensures that the substrates are in their final operational configuration during bonding, preventing the development of differential forces that would occur if flat substrates were forced into curvature after bonding.

Inventive Principle:
Principle #35Parameter changes

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 approach results in liquid-crystal cells that are more resistant to breakage and delamination, maintaining structural integrity when curved, particularly beneficial for glass-based substrates which are prone to stress-related issues.

Implementation Method 1

an edge adhesive disposed within the gap between the first and second substrates and cured after the first and second substrates were bent into their congruently curved configuration

Methodology Applied
Scientific EffectPhotocuring: Photopolymerisation

Data Source

PatentEP3682291B1Curved, arcuately-bonded liquid crystal cell and method of making
Publication Date: 2025.01.01 3M INNOVATIVE PROPERTIES CO
  • EP3682291B1 patent drawingFigure 1~2
  • EP3682291B1 patent drawingFigure 3~4

AI summary

Curved, arcuately-bonded liquid-crystal cells that include substrates held together by an edge adhesive cured after the substrates were bent into a congruently curved configuration; methods of making such cells; and, switchable shutters and automatic darkening filters that include such cells.