Segmented Shaft Geometry for Rollable Displays to Prevent COF Peeling
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Solution Overview
Problem
Current rollable electronic devices with cylindrical shafts cause chips on flexible display screens with chip-on-films to peel off due to increased pressure during rolling, leading to peeling issues between the chip-on-films and the screens.
Innovation Solution
A polyhedral shaft design with planar and arc sections is used, allowing chip-on-films to be directly and flatly rolled on planar surfaces, reducing stress and preventing peeling by distributing the films evenly across the shaft's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cylindrical shaft is used to roll up flexible display screens, then the device structure is simple and easy to manufacture, but the chips on chip-on-films are prone to peel off due to increased pressure during rolling
Solution Approach 1:
The shaft surface is segmented into multiple planar sections instead of being a continuous cylindrical surface. Each planar section provides a flat rolling surface that distributes pressure evenly, preventing chip-on-film peeling while maintaining manufacturing feasibility through modular construction
Solution Approach 2:
The shaft surface is designed with different local geometries: planar sections where chip-on-films contact (providing uniform pressure distribution) and arc sections connecting them (providing smooth transitions). This local differentiation solves the peeling problem without compromising overall structural simplicity
2Reliability
If a polyhedral shaft with planar and arc sections is used, then chip-on-films are protected from peeling during rolling, but the shaft structure becomes more complex
Solution Approach 1:
The shaft is divided into repeating units of planar sections and arc sections, creating a polyhedral structure that protects chip-on-films during rolling while maintaining reasonable structural complexity through pattern repetition rather than arbitrary complexity
Solution Approach 2:
Arc sections are introduced to connect adjacent planar sections, providing smooth transitions that prevent stress concentration. The curved geometry of arc sections complements the flat planar sections to create a structure that protects chips while controlling overall complexity
3Adaptability or versatility
If chip-on-films are arranged on the sides of flexible display screens, then the display functionality is enhanced, but the chips are more susceptible to damage during the rolling process
Solution Approach 1:
The shaft surface is specifically designed with planar sections at locations where chip-on-films will contact during rolling. These planar sections provide uniform pressure distribution exactly where needed (at the chip locations), protecting the chips while allowing the display functionality to be enhanced with side-mounted chip-on-films
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.