Segmented Support Films for Foldable Display Crack Resistance
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Solution Overview
Problem
Existing flexible display devices face challenges in maintaining environmental reliability and preventing defects when bent or folded, particularly due to issues with support film materials and the mounting of driving chips, which can lead to cracking and reduced transmittance.
Innovation Solution
A display device design featuring a display panel with distinct support films and bonding layers in different areas, where the second support film with higher tensile modulus and transmittance is used in the area with the driving chip, and a first support film with lower transmittance but higher glass transition temperature is used in the foldable area, along with a gap between the support films to allow bending, and a carbide layer for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single support film is used across the entire display panel, then the structure is simple and easy to manufacture, but the display device cannot be bent or folded without risking cracking and reduced reliability
Solution Approach 1:
The support film is divided into multiple regions with different material properties: a first support film region with higher glass transition temperature for the folding area, and a second support film region with higher transmittance for the display area. This segmentation allows each region to be optimized for its specific function, enabling bending while maintaining reliability and visual quality.
Solution Approach 2:
Different regions of the support film are assigned different material characteristics tailored to their functional requirements. The folding area uses material with higher glass transition temperature for flexibility and crack resistance, while the display area uses material with higher transmittance for optical performance. This local quality differentiation resolves the contradiction between bendability and reliability.
2Strength
If a support film with high glass transition temperature is used throughout, then the display device can be bent without cracking, but the transmittance in the display area is reduced
Solution Approach 1:
The support film is segmented into distinct material regions: the first support film region with higher glass transition temperature provides crack resistance for bending operations, while the second support film region with higher transmittance ensures optimal light transmission in the display area. This segmentation eliminates the need to compromise between strength and transmittance.
Solution Approach 2:
Each region of the support film is optimized for its specific function: the folding area receives material prioritized for mechanical strength and flexibility, while the display area receives material prioritized for optical properties. This local quality approach allows the display device to achieve both crack resistance and high transmittance simultaneously.
3Adaptability or versatility
If the support film is continuous without gaps, then the structural integrity is maintained, but the display device cannot be folded or bent effectively
Solution Approach 1:
The support film is segmented into discrete first and second support film regions separated by a gap. This segmentation creates a hinge-like structure that enables folding while the individual regions maintain their structural integrity. The gap acts as a flexible joint that accommodates bending without compromising the overall stability of the display panel.
Solution Approach 2:
The gap between the first and second support film regions acts as an intermediary element that facilitates folding. This gap region allows the display device to be bent and folded effectively while the support films on either side maintain their structural integrity. The bonding layers and encapsulation structures serve as mediators that connect the segmented regions while maintaining overall stability.
Data Source
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AI summary
A display device (1) including: a display panel (100) including a first area (A1), a second area (A2) spaced apart from the first area, and a bent third area (A3) between the first and second areas; a first support film (310) coupled to a bottom surface of the display panel and overlapping the first area; and a second support film (330) coupled to the bottom surface of the display panel, overlapping the second area, and spaced apart from the first support film by a gap, the gap overlapping the third area, a top surface of the first support film facing the display panel and an inner side of the first support film form a first angle, a top surface of the second support film facing the display panel and an inner side of the second support film form a second angle, which is greater than the first angle, and the first support film includes a protruding pattern.