Foldable Display Digitizer Stress Management
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Solution Overview
Problem
Foldable display devices face challenges in maintaining sensing reliability and folding characteristics due to stress generated during the folding operation, which can lead to damage in the digitizer components.
Innovation Solution
The design incorporates a digitizer with a connection portion that includes multiple sensing coils and signal lines, which are connected via a single-layer structure, and a support layer with lattice-shaped openings to reduce stress and improve folding characteristics, while also using a protective and reinforcing member to enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the digitizer uses a conventional single-layer connection structure, then the manufacturing process is simple, but the sensing reliability deteriorates due to stress during folding
Solution Approach 1:
The connection portion is divided into multiple layers (first connection layer and second connection layer) with different sensing coils disposed at different heights. This segmentation allows each layer to independently handle sensing functions, reducing stress concentration and improving sensing reliability during folding operations while maintaining manageable structural complexity through systematic layering
Solution Approach 2:
The patent introduces a vertical dimension by stacking sensing coils at different heights (different z-coordinates) within the connection portion. This three-dimensional arrangement distributes mechanical stress across multiple levels and prevents single-point failure, thereby enhancing sensing reliability without significantly increasing planar footprint or manufacturing complexity
2Strength
If the digitizer connection portion is made robust to withstand folding stress, then the folding characteristics worsen due to increased rigidity, but sensing reliability improves
Solution Approach 1:
The patent applies different structural characteristics to different regions: the sensing coil regions use multi-layer robust structures for strength and reliability, while the connection portions between layers use flexible routing and spacing to accommodate folding movements. This local differentiation maintains durability where needed while preserving folding flexibility in critical movement zones
Solution Approach 2:
The digitizer employs composite construction with multiple material layers including flexible substrates, conductive materials for sensing coils, and adhesive layers. This composite structure combines the strength of rigid sensing elements with the flexibility of substrate materials, enabling both durability and良好的 folding characteristics
3Reliability
If multiple sensing coils are disposed at different layers in the connection portion, then sensing reliability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent pre-defines the spatial positions and orientations of sensing coils in the multi-layer structure during the design phase, establishing fixed geometric relationships between layers. This preliminary configuration allows manufacturing processes to follow standardized patterns, reducing the actual precision requirements during assembly while maintaining the intended three-dimensional sensing geometry
Data Source
AI summary
A foldable display device includes a display panel including a first non-folding area, a second non-folding area, and a folding area disposed between the first and second non-folding areas and a digitizer including a first sensing portion, a second sensing portion spaced apart from the first sensing portion in the folding area, and a connection portion extending from one end of the first sensing portion to one end of the second sensing portion. The connection portion includes a first portion extending from the first sensing portion, a second portion extending from the second sensing portion, one or more third portions disposed between the first and second portions and including first and second areas facing each other and a third area disposed between the first and second areas, and a fourth portion disposed between the first and third portions, between the second and third portions, or between two third portions adjacent to each other.