Coating Layer Contact Angle Gradient for Foldable Display Adhesion
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Solution Overview
Problem
Existing display devices with foldable or bendable displays face challenges in maintaining an adequate adhesive force for the coating layer of the upper protective member, leading to a lifting phenomenon of the cover window, especially in the folding area.
Innovation Solution
A display device design that includes a display panel with a folding area and a non-folding area, featuring an upper protective member with a coating layer. The coating layer has distinct contact angles in different portions, with the first portion having a smaller contact angle (90 degrees to 105 degrees) and the second portion having a larger contact angle (110 degrees or more). This design enhances the adhesive force between the first portion and the adhesive member, while maintaining a lower adhesive force for the second portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coating layer has uniform adhesive properties across the entire surface, then the manufacturing process is simple, but the cover window exhibits lifting phenomenon in the folding area due to inadequate adhesive force
Solution Approach 1:
The coating layer is divided into multiple portions with different contact angles: a first portion with a smaller contact angle (90-105 degrees) for enhanced adhesion in the folding area, and a second portion with a larger contact angle (110 degrees or more) for reduced adhesion in non-folding areas. This local differentiation resolves the contradiction by providing high adhesive force where needed while preventing excessive adhesion elsewhere.
2Reliability
If the coating layer has high adhesive force across the entire surface, then the cover window attachment is secure, but the lifting phenomenon occurs in the folding area due to excessive adhesion
Solution Approach 1:
The coating layer is differentiated into regions with distinct contact angles: the first portion (90-105 degrees) provides strong adhesion for secure attachment, while the second portion (110 degrees or more) provides reduced adhesion to prevent lifting in non-folding areas. This local quality variation allows the system to achieve secure attachment without suffering from excessive adhesion-induced lifting.
3Ease of manufacture
If the coating layer has low adhesive force, then the manufacturing process is simple, but the adhesive force is insufficient to prevent cover window lifting
Solution Approach 1:
Instead of applying uniform coating properties, the system creates local variations in contact angle within the coating layer. The first portion achieves enhanced adhesion (90-105 degrees) through controlled coating conditions, while the second portion maintains reduced adhesion (110 degrees or more). This approach maintains manufacturing simplicity while achieving the required adhesive force in critical areas.
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 enhanced adhesive force in the first portion effectively minimizes or reduces the lifting phenomenon of the cover window, while the reduced adhesive force in the second portion prevents excessive adhesion issues, thereby improving the overall durability and reliability of the display device.
Implementation Method 1
a contact angle of the first portion is different from a contact angle of the second portion
Implementation Method 2
a first adhesive force, which is an adhesive force between the first portion and the adhesive member, is different from a second adhesive force, which is an adhesive force between the second portion and the adhesive member
Data Source
AI summary
A display device includes: a display panel including a folding area and a non-folding area on one side of the folding area; and an upper protective member on a first surface of the display panel and including a coating layer, wherein the coating layer includes: a first portion overlapping the folding area; and a second portion on one side of the first portion, wherein a contact angle of the first portion is different from a contact angle of the second portion.