Patterned Backfilm Mitigates Wrinkling in Curved Flexible Displays
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Solution Overview
Problem
Shaping flexible display panels with compound curved corners for electronic devices poses challenges such as wrinkling and cracking due to compressive and tensile strains during the manufacturing process, which can result in undesirable appearance and functionality.
Innovation Solution
Incorporating a patterned backfilm with varying coefficients of thermal expansion, Young's modulus, and thickness to absorb and mitigate these strains, allowing the flexible display panel to conform to desired curvature while minimizing wrinkling and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a flexible display panel is shaped to have compound curved corners, then the display can accommodate desired electronic device shape and achieve aesthetically pleasing appearance, but compressive stress is imparted on the flexible display panel which causes undesired wrinkling or buckling
Solution Approach 1:
A film layer is introduced as an intermediary element between the flexible display panel and the mold during the shaping process. This film absorbs the compressive stress generated when the display panel is formed into compound curved corners, preventing the panel itself from experiencing the stress that would cause wrinkling or buckling. The film acts as a mediator that takes on the harmful mechanical stress while allowing the desired shape to be achieved.
2Shape
If a flexible display panel is shaped to have compound curved corners, then the display can accommodate desired electronic device shape, but the flexible display panel may crack due to tensile strain generated during the manufacturing process
Solution Approach 1:
The film layer serves as a protective intermediary that absorbs tensile strain during the manufacturing process. When the flexible display panel is shaped into compound curved corners, tensile stresses are generated that could cause cracking. The film absorbs these tensile forces, protecting the display panel from cracking while still allowing the panel to be shaped into the desired compound curved configuration.
3Reliability
If a film is included to absorb forces in the display panel, then wrinkling and cracking are mitigated, but the device complexity increases
Solution Approach 1:
The solution uses a thin film layer that can be easily integrated into the existing display panel structure. The film is designed to be flexible and conform to the curvature of the display panel, allowing it to absorb stresses without adding significant structural complexity. The film can be applied as a simple coating or layer during the manufacturing process, minimizing the increase in device complexity while effectively mitigating wrinkling and cracking.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of a patterned backfilm effectively reduces strain-induced wrinkling and cracking, enabling the production of electronic devices with aesthetically pleasing, curved surfaces that maintain functionality and durability.
Implementation Method 1
The film may have a coefficient of thermal expansion that is different than that of the display panel. The coefficient of thermal expansion mismatch may cause the film to oppose the forces on the flexible display panel caused by bending, thus mitigating wrinkling in the flexible display panel.
Implementation Method 2
Instead or in addition, the film may have portions with different Young's modulus magnitudes or different thickness magnitudes. Force absorbing films may be incorporated above the display panel and/or below the display panel.
Implementation Method 3
The display may include a flexible substrate. For example, the display may include a flexible display layer such as an organic light-emitting diode (OLED) display layer with an array of pixels configured to display images for a user.
Data Source
AI summary
An electronic device may have a display overlapped by a display cover layer. Portions of the surface of the display and cover layer may have curved profiles. For example, a display cover layer may have transparent sidewall portions with curved surface profiles. The transparent sidewall portions of the display cover layer may include rounded corners having areas of compound curvature. A flexible display panel may be pressed over a mold to impart desired curvature (such as compound curvature) to the flexible display panel. To mitigate wrinkling in a flexible display panel molded to have compound curvature, a film may be included that absorbs force in the display panel. The film may have a coefficient of thermal expansion that is different than that of the display panel. Instead or in addition, the film may have portions with different Young's modulus magnitudes or different thickness magnitudes.