Flexible Display Adhesive Film Stacking for Foldability
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Solution Overview
Problem
Flexible display apparatuses face challenges in maintaining foldability and preventing bubble generation, cracking, and moisture damage when folded, particularly due to the vulnerability of OLED panels to moisture and oxygen, which can lead to increased thickness and reduced foldability.
Innovation Solution
A flexible display apparatus is designed with a specific stacking order of a display part, first adhesive film, optical film, and second adhesive film, where the second adhesive film has a low water vapor transmission rate and the first adhesive film has a lower restoration force, ensuring efficient folding and improved durability by preventing moisture ingress and maintaining adhesion under high temperature and humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing material is applied to block moisture and oxygen from entering the OLED panel, then protection against moisture and oxygen is improved, but thickness of the flexible display apparatus increases
Solution Approach 1:
The patent uses a thin film structure (display part, optical film, window film stacked in sequence) that provides protection while maintaining flexibility and minimizing thickness. The layered film structure acts as a barrier against moisture and oxygen without requiring additional thick sealing materials.
2Strength
If additional member is mounted to improve impact resistance of the OLED, then impact resistance is improved, but thickness increases and foldability deteriorates
Solution Approach 1:
The patent employs a flexible stacked film structure (display part, optical film, window film) that provides impact resistance through its layered configuration while maintaining the ability to fold. The thin film layers distribute impact forces without requiring additional thick protective members that would hinder foldability.
3Adaptability or versatility
If the flexible display apparatus is folded towards the display part, then utility for simultaneous viewing is improved, but bubble generation and cracking may occur
Solution Approach 1:
The patent uses a flexible stacked film structure that can be folded without generating bubbles or cracks. The thin film layers (display part, optical film, window film) are designed to flex together harmoniously, maintaining adhesion during folding while enabling the display to be viewed from multiple angles simultaneously.
4Strength
If OCA films are used to adhere display part, optical film, and window film, then adhesion is improved, but yellow index variation may occur
Solution Approach 1:
The patent employs a composite stacked structure of display part, optical film, and window film that achieves strong adhesion while minimizing yellow index variation. The specific combination and arrangement of these materials provide both bonding strength and optical stability, preventing color degradation over time.
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 solution enhances the foldability and reliability of the flexible display apparatus by preventing bubble generation, cracking, and delamination, while maintaining good adhesion and impact resistance, ensuring the OLED panel's longevity and performance.
Implementation Method 1
the second adhesive film has a water vapor transmission rate of about 200 g/m2·24 hr or less
Implementation Method 2
the display part, the optical film, and the window film may be adhered to each other via optically clear adhesive (OCA) films
Data Source
AI summary
Disclosed is a flexible display apparatus. The flexible display apparatus includes a display part, a first adhesive film, an optical film, a second adhesive film, and a window film sequentially stacked, and the second adhesive film has a water-vapor permeability of about 200 g/m2·24 hr or less, and the first adhesive film has a lower restoration force than the second adhesive film, as calculated by the Equation B set forth herein.