Zigzag Wiring in Foldable Display Stress Reduction
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Solution Overview
Problem
Foldable organic light emitting display devices with in-cell touch structures face defects in touch sensing due to stress concentration at the folding area, which can lead to disconnection or cracking of wiring and touch electrode parts.
Innovation Solution
A foldable display device design featuring a lower and upper base material with a thin film transistor array and organic light emitting array, where the touch electrode array is bonded to the organic light emitting array using an adhesive layer, and the routing lines in the folding part are designed with a zigzag shape and uneven depth level to mismatch with the folding angle, reducing stress and preventing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the foldable display device uses a conventional wiring structure in the folding part, then the device can be manufactured with simple structure, but stress concentration at the folding area causes disconnection or cracking of wiring and touch electrode parts
Solution Approach 1:
The wiring pattern in the folding part is designed with a zigzag shape instead of a straight line. This curved/angled configuration allows the wiring to flex and accommodate the folding motion without concentrating stress at a single point, thereby preventing disconnection and cracking while maintaining structural simplicity
Solution Approach 2:
The wiring structure is designed with uneven depth levels in the folding part, creating a three-dimensional configuration. This dimensional variation allows different sections of the wiring to be at different depths, distributing stress across multiple levels and preventing stress concentration that would lead to failure
2Reliability
If the wiring in the folding part is designed with zigzag shape and uneven depth level, then stress concentration is reduced and touch sensing reliability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The zigzag wiring pattern can be fabricated using standard photolithography and etching processes by defining the pattern in the mask layer. The curved/angled geometry is achieved through conventional patterning techniques, adding minimal complexity to the manufacturing process while significantly improving reliability
Solution Approach 2:
The uneven depth level structure can be created by forming the wiring at different elevations using multi-layer conductor structures or by creating recesses and protrusions in the substrate. This three-dimensional configuration is achievable through standard semiconductor fabrication processes, balancing manufacturing feasibility with stress distribution benefits
Data Source
AI summary
A foldable display device may prevent defects in touch sensing, caused by stress concentrated at a folding part. A foldable display device may include a lower base material and an upper base material, each base material including at least one folding part and non-folding parts in a display area; a thin film transistor array on the lower base material; an organic light emitting array on the thin film transistor array; a touch electrode array disposed on the upper base material, and oppositely bonded to the organic light emitting array disposed opposite to the touch electrode array by an adhesive layer; and a plurality of wirings having a zigzag shape and uneven depth level in the folding part on the upper base material.