Variable Thickness Glass Layer for Foldable Display Crease Reduction
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Solution Overview
Problem
Flexible display panels in foldable electronic devices face challenges with creases and stress distribution during repeated folding and unfolding, leading to potential deformation and damage.
Innovation Solution
A display protection layer with a glass layer having varying thicknesses in the folding area, including a thicker central portion and a thinner connecting area, is used to distribute stress and reduce creasing, while maintaining the display's flexibility and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform thickness glass layer is used in the folding area, then the manufacturing process is simple, but stress concentrates during folding causing creases and potential damage
Solution Approach 1:
The glass layer is designed with non-uniform thickness, featuring a first area with greater thickness and a second area with lesser thickness in the folding region. This local variation in quality allows the thicker portion to withstand compressive forces while the thinner portion accommodates tensile forces during folding, thereby distributing stress and preventing creases without complicating the overall manufacturing process
2Strength
If the glass layer thickness is increased to improve impact resistance, then the display protection capability is enhanced, but the device thickness increases and folding capability is compromised
Solution Approach 1:
Rather than uniformly increasing the glass layer thickness across the entire display, the invention applies greater thickness only in the first area of the folding region where impact forces are most concentrated. The second area maintains a thinner profile, preserving the device's overall thinness and folding capability while still providing enhanced impact resistance where needed
3Reliability
If a thicker glass layer is used in the folding area, then stress distribution is improved, but the device thickness increases
Solution Approach 1:
The glass layer thickness is strategically varied within the folding area, with the first area having greater thickness to handle stress concentration and the second area having lesser thickness to maintain overall device thinness. This localized thickness variation achieves improved stress distribution without proportionally increasing the device's overall thickness
Solution Approach 2:
The invention addresses the thickness problem by introducing a thickness gradient within the folding area rather than uniformly increasing thickness. The transition from the thicker first area to the thinner second area creates a dimensional variation that distributes stress effectively while keeping the average device thickness acceptable
Data Source
AI summary
According to an embodiment of the disclosure, an electronic device may comprise a first housing, a second housing configured to provide a motion relative to the first housing, a flexible display configured to transform in response to the motion of the second housing relative to the first housing, and a display protection layer disposed on one surface of the flexible display facing in a first direction. The display protection layer may include a glass layer including a first flat area having a first thickness and disposed on the first housing, a second flat area disposed on the second housing, and a folding area connecting the first flat area and the second flat area, and a coating layer disposed between the glass layer and the flexible display. The folding area of the glass layer may include a first area having a second thickness different from the first thickness and a second area connecting the first area and the flat area and having a third thickness smaller than the second thickness. The first area may protrude in a second direction opposite to the first direction as compared with the second area.