Adhesive Sheet with Variable Rigidity for Flexible Display
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Solution Overview
Problem
Conventional adhesives for flexible displays fail to maintain adhesion and return to their original state after repeated folding due to differences in rigidity and strain between the display panel and the back plate, leading to deformation and prolonged restoration times.
Innovation Solution
An adhesive sheet with distinct regions of varying rigidity, treated to create neutral planes, is used between the display panel and the back plate, allowing for efficient folding and unfolding without permanent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a general adhesive made of single material is used to bond the display panel and back plate, then adhesion is achieved, but the adhesive cannot respond to folding or bending and fails to return to original state
Solution Approach 1:
The adhesive sheet is divided into multiple regions with different rigidities. The first region has higher rigidity to maintain adhesion strength, while the second region has lower rigidity to respond to folding and bending movements. This local differentiation allows the adhesive to simultaneously achieve reliable bonding and adaptability to structural changes during folding operations.
Solution Approach 2:
The adhesive sheet is constructed as a composite structure with multiple regions having different material properties. By combining regions of high rigidity and low rigidity within a single adhesive sheet, the system achieves both strong adhesion and flexibility to accommodate folding movements, resolving the contradiction between bonding reliability and folding adaptability.
2Reliability
If adhesive material rigidity is controlled to match flexibility of display panel or back plate, then adhesion is achieved, but opposite surfaces deform due to length variation difference
Solution Approach 1:
Different regions of the adhesive sheet are assigned different rigidities to perform different functions. The higher rigidity region maintains adhesion strength and prevents detachment, while the lower rigidity region accommodates length variations and prevents surface deformation. This local differentiation resolves the conflict between maintaining strong adhesion and preventing deformation.
3Ease of manufacture
If adhesive is made with uniform rigidity, then manufacturing is simple, but the adhesive cannot return to original condition after folding operations
Solution Approach 1:
The adhesive sheet incorporates regions with different rigidities to enable restoration after folding. The lower rigidity region allows the adhesive to flex and deform during folding, while the higher rigidity region maintains structural integrity. This differentiation enables the adhesive to return to its original flat state after folding operations, improving restoration capability.
4Device complexity
If adhesive sheet has single rigidity value, then structural simplicity is maintained, but slip occurs between display panel and back plate during folding
Solution Approach 1:
The adhesive sheet is divided into regions with different rigidities to prevent slip during folding operations. The higher rigidity region provides strong bonding force to prevent relative movement between the display panel and back plate, while the lower rigidity region accommodates the differential curvature radii that occur during folding. This local differentiation effectively prevents slip while maintaining reasonable structural complexity.
Data Source
AI summary
Provided are an adhesive and a flexible display including the same. The adhesive can avoid deformation and can easily return to the original state thereof upon unfolding by including an adhesive sheet on both surfaces thereof and performing treatment on specific areas to change the rigidity thereof and make the areas different in rigidity and thereby form a plurality of neutral planes.