Flexible Touch Screen Panel With Concavo-Convex Substrate
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Solution Overview
Problem
Flexible touch screen panels face issues with cracking and driving failure due to bending or folding, as the conductive sensing electrodes are prone to damage when subjected to deformation.
Innovation Solution
A flexible touch screen panel design featuring a substrate with concavo-convex patterns on one or both surfaces, where sensing electrodes are formed in the concave portions of these patterns, and connectors are used to connect the electrodes, made of transparent or low-resistance metallic materials, to enhance flexibility and prevent plastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flexible touch screen panel uses a flat substrate with sensing electrodes formed directly on it, then the structure is simple and manufacturing is easy, but the conductive layer cracks during bending or folding operations causing driving failure
Solution Approach 1:
The substrate is designed with a concavo-convex pattern featuring curved surfaces instead of a flat surface. The convex portions provide arch-like structural support that resists cracking during bending, while the concave portions accommodate the sensing electrodes. This curvature-based design maintains manufacturing simplicity while significantly improving the reliability of the conductive layer under flexing conditions.
Solution Approach 2:
The substrate exhibits non-uniform local properties through the concavo-convex pattern. The convex portions have higher structural strength to prevent cracking, while the concave portions provide electrode accommodation zones. This local differentiation allows the same substrate to simultaneously achieve ease of manufacture and high reliability in different regions.
2Reliability
If the sensing electrodes are formed in concave portions of concavo-convex patterns on the substrate, then flexibility and resistance to cracking are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The concavo-convex pattern with its curved geometry provides inherent structural reinforcement that prevents electrode cracking during bending. The electrodes formed in the concave portions naturally follow the curved substrate topology, which distributes stress more evenly and prevents the formation of sharp stress concentration points that would cause cracking.
Solution Approach 2:
The electrodes are strategically positioned only in the concave portions of the substrate pattern, where the local geometry provides both mechanical protection and electrical functionality. This localized electrode placement reduces the overall complexity by concentrating the conductive elements in specific protected zones rather than requiring a complete electrode network across the entire flexible surface.
3Illumination intensity
If transparent conductive material such as ITO is used for sensing electrodes, then transparency is maintained, but the material is prone to cracking when bending or folding is performed
Solution Approach 1:
The transparent conductive material is selectively deposited only in the concave portions of the concavo-convex substrate pattern. This localized deposition ensures that the transparent electrodes are positioned in regions where the substrate geometry provides mechanical protection against cracking, while maintaining the necessary transparency for display visibility.
Solution Approach 2:
The curved concave portions of the substrate provide a geometry that distributes bending stresses away from the electrode material. The arch-like structure of the convex portions surrounding each concave electrode zone acts as a protective frame, preventing the transparent conductive material from cracking during flexing while preserving its optical transparency.
4Ease of operation
If the substrate is made thin to achieve flexibility, then ease of bending is improved, but the conductive layer becomes more vulnerable to damage
Solution Approach 1:
The concavo-convex pattern introduces geometric reinforcement to the thin substrate. The convex portions create arch-like structures that provide mechanical strength and crack resistance, while the overall thin profile maintains flexibility. This allows the substrate to be thin enough for easy bending while the patterned geometry prevents the conductive layer from becoming vulnerable to damage.
Solution Approach 2:
The substrate exhibits spatially varying mechanical properties through the concavo-convex pattern. The convex portions have locally enhanced strength to protect the electrodes, while the thin regions maintain flexibility. This local differentiation allows the same thin substrate to simultaneously achieve ease of bending and protect the conductive layer from damage.
Data Source
AI summary
A flexible touch screen panel includes a substrate, first and second sensing electrodes and conductive lines. The substrate includes an active area and a non-active area positioned at the outside of the active area when viewed in a thickness direction thereof. The substrate further includes a first surface and a second surface. The first and second sensing electrodes are formed over the active area of the substrate. The first sensing electrodes are formed to be connected along a first direction, and second sensing electrodes are formed to be connected along a second direction intersecting the first direction. The conductive lines are formed over the non-active area of the substrate, and electrically connect the first and second sensing electrodes to an external driving circuit. In the flexible touch screen panel, one or more concavo-convex patterns are formed on one or both of the first and second surfaces.