Polyhedral Shaft Structure for Rollable Display COF Protection
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Solution Overview
Problem
Chips on chip-on-films (COFs) arranged on the sides of flexible display screens in rollable devices are prone to peel off during the rolling process due to the use of solid cylindrical shafts, leading to peeling risks between the COFs and the flexible display screens.
Innovation Solution
A polyhedral shaft design with planar and arc sections is employed, allowing the COFs to be directly and flatly rolled on planar surfaces, reducing stress and preventing cutting, thereby addressing the peeling issue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a solid cylindrical shaft is used to roll up the flexible display screen, then the shaft structure is simple and easy to manufacture, but the chips on chip-on-films arranged on sides of the flexible display screen are prone to peel off during the rolling process
Solution Approach 1:
The shaft is divided into multiple planar sections (first planar sections) and arc sections (first arc sections) that are interconnected. This segmentation allows the shaft surface to be composed of flat regions where COFs can be directly and flatly rolled, reducing stress concentration and preventing chip peeling, while maintaining a manageable structural complexity through modular segmentation.
Solution Approach 2:
Different sections of the shaft are given different geometric properties: planar sections provide flat surfaces for stress-free COF rolling, while arc sections provide curved transitions. This local differentiation of surface quality ensures that COFs are always rolled on appropriate surfaces, preventing peeling at critical locations while maintaining overall structural integrity.
2Ease of manufacture
If a solid cylindrical shaft is used, then the manufacturing process is simple, but stress concentration occurs during rolling causing COFs to be cut or peeled
Solution Approach 1:
The shaft surface is segmented into planar and arc sections, creating a polygonal cross-section rather than a smooth cylinder. This segmentation eliminates continuous curvature that causes stress concentration, distributing rolling stress evenly across planar surfaces and protecting COFs from cutting or peeling while keeping the manufacturing process relatively simple.
Solution Approach 2:
The shaft incorporates arc sections with controlled curvature radii (greater than half the shaft radius) that provide smooth transitions between planar sections. These arc sections are designed with appropriate curvature to prevent stress concentration while maintaining the protective effect of the polygonal structure, balancing geometric protection with manufacturing feasibility.
Data Source
AI summary
A shaft and a display device are disclosed. The display device includes the shaft including a plurality of planar sections and arc sections. Each of the arc sections is disposed between adjacent ones of the planar sections. A flexible display screen includes a first side, a third side, and a second side sequentially arranged, and the third side is fixed on the shaft. When the flexible display screen is rolled on the shaft, each chip-on-film is placed on a corresponding one of the planar sections, so that a problem that the chip-on-films arranged on the flexible display screen are prone to peel is solved.