Variable-Force Bonding for Durable Foldable Display Panels
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Solution Overview
Problem
Foldable display devices face damage and durability issues due to bending stress when folded, as the flexible display panel is restricted and cannot release stress caused by contraction and extension during folding.
Innovation Solution
A foldable display device design with a case that includes a hinge portion and supports, using a bonding member with varying bonding forces and displacement properties to allow the flexible display panel to detach and slide relative to the case, reducing bending stress by releasing it during folding and unfolding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the flexible display panel is fixed to the case using a bonding member, then the display panel is supported and positioned, but bending stress accumulates and causes damage during folding
Solution Approach 1:
The bonding member is designed to be displacementable relative to the support along the thickness direction, allowing it to dynamically adjust its position. When the flexible display panel is folded, the bonding member can move to release bending stress, preventing damage. When unfolded, it returns to its original position to provide support. This dynamic behavior resolves the contradiction between maintaining support stability and allowing stress relief during folding.
Solution Approach 2:
The bonding member's bonding force is designed to vary based on the folding state. The bonding force is stronger when the panel is unfolded (providing good support) and weaker when folded (allowing stress release). This parameter change enables the bonding member to adapt to different operational states, simultaneously achieving both support stability and durability.
2Strength
If the bonding member has strong bonding force to secure the flexible display panel, then the panel is firmly fixed, but the panel cannot release stress during folding
Solution Approach 1:
The bonding member transitions from a static strong bond to a dynamic system that can weaken when needed. The displacementable design allows the bonding member to maintain strong bonding force during normal use (providing secure fixation) but can move to reduce bonding force when folding occurs, thereby releasing stress and preventing damage.
Solution Approach 2:
The bonding member is designed with the capability to release stress before damage occurs. By allowing displacement along the thickness direction, the system pre-establishes a stress relief mechanism that activates when folding begins, cushioning against the harmful bending stress before it can cause damage to the flexible display panel.
3Manufacturing precision
If the bonding member is rigid to maintain panel position, then positioning is accurate, but the panel cannot slide to reduce stress during folding
Solution Approach 1:
The bonding member embodies dynamic positioning capability. During normal operation, it maintains accurate positioning through its bonding force. When folding occurs, it can displace along the thickness direction to allow the panel to slide and release stress. This dynamic behavior enables the system to achieve both positioning accuracy and stress release capability as needed.
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 design effectively reduces bending stress and improves durability of the flexible display panel by allowing it to detach and slide relative to the case, extending its lifespan to over 200,000 folds compared to 11,500 folds without this design.
Implementation Method 1
reducing a bending stress generated in the flexible display panel when the foldable display device is folded
Implementation Method 2
The second bonding member portion may include a pressure sensitive adhesive and the bonding force of the second bonding member portion with respect to the support may be in a range from about 10 gf/cm to about 1,500 gf/cm
Data Source
AI summary
A foldable display device includes a flexible display panel, a case supporting the flexible display panel, a bonding member fixing the flexible display panel to the case. The case includes a hinge portion, and supports respectively coupled to the hinge portion at opposing sides of the hinge portion. The flexible display panel includes a bendable area corresponding to the hinge portion, and planar areas respectively at opposing sides of the bendable area and corresponding to the supports of the case. The bonding member is between a support of the case and the corresponding planar area of the flexible display panel, and is displaceable with respect to the support along one of a thickness direction and a width direction of the flexible display panel when the flexible display panel is folded.