Foldable Display Adhesive Stress Control
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Solution Overview
Problem
Foldable display devices with thin plastic cover windows are prone to deformation and loss of flatness under external impact, and introducing a rigid structure to improve rigidity can cause stress that damages other components during folding.
Innovation Solution
A foldable display device design that includes a display panel with a folding area and a non-folding area, a back plate unit with multiple back plates, and adhesive layers with varying adhesiveness to control stress, where the adhesiveness at the edge portions is weaker than at the center to facilitate slipping and reduce stress propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a rigid structure (back plate unit and frame) is introduced below the display panel to improve flatness, then the flatness of the cover window is improved, but stress is caused during folding which results in damage to other components
Solution Approach 1:
The adhesive layers are divided into different regions with different adhesiveness properties. Specifically, the adhesive layers have a first adhesive part and a second adhesive part, where the second adhesive part has less adhesive strength than the first adhesive part. This segmentation allows different portions of the adhesive layer to serve different functions during folding.
Solution Approach 2:
Different regions of the adhesive layers are assigned different adhesive strengths based on their location. The edge portions have weaker adhesiveness to allow stress relief during folding, while the center portion maintains stronger adhesiveness to ensure structural stability and flatness support.
2Adaptability or versatility
If the cover window is formed of a thin plastic film to enable folding, then the device can be folded freely, but the cover window becomes deformed by external impact and loses flatness
Solution Approach 1:
The device employs a composite structure combining a thin flexible display panel with a rigid back plate unit and frame. This composite construction provides structural support to maintain flatness while allowing the display panel to remain flexible enough for folding.
3Strength
If a rigid structure is introduced to increase rigidity, then the rigidity of the device is improved, but stress from the rigid structure damages other configurations during folding
Solution Approach 1:
The adhesive layers act as an intermediary element between the rigid back plate unit/frame and the flexible display panel. By designing the adhesive layers with different adhesiveness in different regions, they mediate the stress transfer, allowing the rigid structure to provide support while preventing excessive stress transmission to the flexible components during folding.
Data Source
AI summary
A foldable display device is disclosed. The foldable display device includes a display panel including a folding area and a non-folding area, a back plate unit, and a plurality of adhesive layers disposed between the display panel and the back plate unit and between the back plate units. Some of the plurality of adhesive layers includes a first adhesive part and a second adhesive part having different adhesiveness. Therefore, an adhesiveness of the plurality of adhesive layers is controlled to reduce the stress generated at the time of folding the foldable display device.