Multi-Layer Adhesive Structure for Flexible Display Bending Stability
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Solution Overview
Problem
Existing flexible electroluminescent display devices face challenges in maintaining display performance while reducing bezel width and preventing cracks in the bending area due to interference and movement during bending.
Innovation Solution
A flexible display device with a bezel-bending structure that includes a metal plate and adhesive members with conductive layers to enhance grounding force and fix the bending portion, using a support layer and conductive adhesive layers to minimize cracks and improve bezel width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a bending area with extreme curvature is used to reduce bezel area, then the bezel width is reduced, but cracks occur in the bending portion due to interference between the bending portion and components
Solution Approach 1:
A curvature adjustment layer is introduced as an intermediary component between the bending area and the micro-coating layer. This layer has a smaller thickness than the micro-coating layer and is positioned to adjust the neutral plane, reducing stress concentration at the bending area and preventing cracks while maintaining the curved bezel structure
Solution Approach 2:
The thickness parameter of the curvature adjustment layer is specifically controlled to be smaller than the micro-coating layer thickness. This parameter change optimizes the stress distribution in the bending area, allowing the extreme curvature needed for narrow bezel width while preventing crack formation
2Area of stationary object
If the thickness of the micro-coating layer is minimized to allow bending, then the bezel area is reduced, but the bending portion moves (flows) increasing interference with components
Solution Approach 1:
The curvature adjustment layer serves as a mediator that stabilizes the bending portion by adjusting the neutral plane position. This prevents excessive movement or flow of the bending area while maintaining the minimized micro-coating layer thickness needed for flexible bending
Solution Approach 2:
The curvature adjustment layer is positioned beforehand to cushion and control the movement of the bending portion. This pre-positioned layer prevents interference between the bending area and underlying components by managing the deformation behavior during bending
3Ease of operation
If a soft foam material is used as pressure sensitive adhesive to fix the bending portion, then flexibility is maintained, but fixing force is insufficient allowing movement during impact
Solution Approach 1:
The adhesive member is constructed as a composite structure combining a support layer made of foam material with adhesive layers on its surfaces. This composite structure provides both the flexibility needed for bending and the sufficient fixing force to prevent movement during impact, resolving the contradiction between softness and strength
Data Source
AI summary
A flexible display device example includes a display panel including an active area, a non-active area, and a bending area and having one edge that is bent in a rear direction to have a predetermined curvature, first and second back plates disposed on a rear surface of the display panel, a metal plate disposed on a rear surface of the first back plate and an adhesive member disposed between the metal plate and the second back plate, and including a support layer, a first adhesive layer and a third adhesive layer disposed on an upper portion of the support layer, and a second adhesive layer disposed on a lower portion of the support layer, wherein the third adhesive layer may include a conductive material and may have conductivity. Thus, fixing force of a bending portion may increase, thereby preventing cracks in the bending portion that may occur during drop evaluation.