Foldable Display Touch Electrode Layout Against Bending Stress
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Solution Overview
Problem
Display devices with touch sensing functions are prone to signal line fractures in bending areas due to stress concentration, which can lead to damage.
Innovation Solution
The display device incorporates a design with touch sensors and signal lines that have inclined ends relative to the bending axis, reducing stress concentration and preventing signal line damage in bending areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal lines are disposed perpendicular to the bending axis in the bending area, then touch sensing coverage is maximized, but stress concentration occurs leading to signal line fracture
Solution Approach 1:
The signal lines in the bending area are designed with asymmetric orientation relative to the bending axis. Specifically, the signal lines are disposed at an angle of 45 degrees or more (e.g., 60, 90, or 120 degrees) relative to the bending axis, rather than being perpendicular to it. This asymmetric arrangement reduces stress concentration during bending operations, thereby preventing signal line fracture while maintaining touch sensing functionality.
2Ease of manufacture
If connection electrodes have perpendicular edges to the bending axis, then manufacturing is simplified, but stress concentration increases causing electrode fracture
Solution Approach 1:
The connection electrodes are designed with asymmetric edge configurations relative to the bending axis. At least one edge of each connection electrode is disposed at an angle of 45 degrees or more relative to the bending axis, rather than being perpendicular. This asymmetric design distributes stress more evenly during bending, preventing electrode fracture while remaining compatible with standard manufacturing processes.
3Measurement precision
If touch signal lines are arranged in a grid pattern, then touch sensing precision is improved, but stress concentration in bending area increases
Solution Approach 1:
The touch signal line arrangement transitions from a uniform grid pattern in the flat area to a locally modified pattern in the bending area. In the bending area, signal lines are reoriented at angles of 45 degrees or more relative to the bending axis, while maintaining the grid structure in non-bending regions. This local modification preserves touch sensing precision in the display area while enhancing signal line durability in the bending region through reduced stress concentration.
Data Source
AI summary
A display device including a display panel including a flat area including a first display area and a first peripheral area adjacent to the first display area and a bending area including a second display area and a second peripheral area adjacent to the second display area, and an input sensing unit on the display panel. The input sensing unit includes first touch sensors having a mesh shape, extending in a first direction parallel to a bending axis of the bending area, and arranged in a second direction crossing the first direction, second touch sensors having a mesh shape, extending in the second direction, and arranged in the first direction, first connection electrodes respectively connected to ends of the first touch sensors, second connection electrodes respectively connected to ends of the second touch sensors, and touch signal lines connected to the first connection electrodes and the second connection electrodes.