Polyhedral Drum Rollable Display Reducing Shear Stress
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Solution Overview
Problem
Flexible display panels experience shear stress when rolled, leading to potential peeling or deformation of protection films due to prolonged bending, which existing technologies fail to adequately address.
Innovation Solution
A rollable display design featuring a polyhedral drum with alternating flat and curved surface portions, where a flexible panel is wound around the drum with overlapping tapered top and tail portions, and an intervening layer, ensuring uniform thickness and reducing shear stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a flexible display panel is rolled into a wound state, then the display can be compacted and stored, but shear stress is applied to the bent portion causing protection film peeling or deformation
Solution Approach 1:
The drum surface is segmented into multiple flat surface portions and curved surface portions. The flexible display panel is wound such that different sections correspond to different drum surface portions, distributing the bending stress across multiple segments rather than concentrating it in one location.
Solution Approach 2:
Different portions of the drum surface have different geometries (flat vs. curved) tailored to specific functions. The flat surface portions provide regions where the flexible panel experiences minimal bending stress, while curved portions accommodate necessary curvature. This local optimization prevents uniform stress distribution that would cause damage.
2Volume of moving object
If the flexible panel is wound tightly around the drum, then the compactness is improved, but the shear stress concentration increases causing deformation
Solution Approach 1:
The solution moves from a simple cylindrical drum to a polyhedral drum with multiple flat and curved surface portions. This dimensional complexity allows the panel to be wound in a manner that utilizes both flat and curved surfaces, distributing stress in multiple spatial dimensions rather than along a single curved path.
3Reliability
If the top and tail portions of the flexible panel are made thick for structural strength, then the panel reliability is improved, but the uniformity of thickness across the wound state is compromised
Solution Approach 1:
The top and tail portions of the flexible panel are designed with asymmetric tapered shapes. The top portion tapers in one direction while the tail portion tapers in the opposite direction. This asymmetric design allows both portions to be positioned on the same flat surface portion of the drum, creating a symmetric stacked configuration that achieves thickness uniformity despite the asymmetric individual shapes.
Data Source
AI summary
A rollable display may include a polyhedral drum and a flexible panel. The polyhedral drum includes a plurality of substantially flat surface portions and a plurality of curved surface portions. The plurality of curved surface portions connect adjacent flat surface portions to each other on an outer circumferential surface of the polyhedral drum. The flexible panel is disposed around the outer circumferential surface of the polyhedral drum. A top portion and a tail portion of the flexible panel may overlap each other on substantially the same flat surface portion of the polyhedral drum. The top portion and the tail portion correspond to respective ends of the flexible panel.