Laminated Film with Graded Modulus for Foldable Display Windows
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Solution Overview
Problem
Existing plastic films for display device protective windows struggle to simultaneously achieve high mechanical properties, excellent toughness, and superior optical properties, making them unsuitable for flexible or foldable displays.
Innovation Solution
A laminated film structure comprising two films with specific properties, where the second film has a higher tensile modulus and transmittance than the first film, and optionally includes additional layers like a hard coating, adhesive, or hyperelastic layer, to enhance toughness and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid glass substrate is used for the protective window, then mechanical strength and hardness are improved, but toughness and flexibility deteriorate
Solution Approach 1:
The protective window is divided into multiple plastic film layers (first film, second film, third film) with different properties. Each layer contributes specific functions: the first film provides basic protection, the second film enhances toughness, and the third film improves hardness. This segmentation allows the system to achieve both strength and toughness that a single material cannot provide.
Solution Approach 2:
The invention uses a composite structure of multiple plastic films with different molecular structures and properties. By combining films with varying tensile moduli, elongations at break, and hardness values, the laminated structure achieves superior mechanical strength and toughness simultaneously, overcoming the limitations of single-material protective windows.
2Reliability
If a plastic film is used to substitute glass, then flexibility and toughness are improved, but mechanical strength and hardness deteriorate
Solution Approach 1:
The protective window is divided into multiple plastic film layers (first film, second film, third film) with different properties. Each layer contributes specific functions: the first film provides basic protection, the second film enhances toughness, and the third film improves hardness. This segmentation allows the system to achieve both strength and toughness that a single material cannot provide.
Solution Approach 2:
The invention uses a composite structure of multiple plastic films with different molecular structures and properties. By combining films with varying tensile moduli, elongations at break, and hardness values, the laminated structure achieves superior mechanical strength and toughness simultaneously, overcoming the limitations of single-material protective windows.
3Ease of manufacture
If a single plastic film is used, then manufacturing simplicity is maintained, but simultaneous achievement of mechanical properties, toughness, and optical properties becomes difficult
Solution Approach 1:
The protective window is divided into multiple plastic film layers (first film, second film, third film) with different properties. Each layer contributes specific functions: the first film provides basic protection, the second film enhances toughness, and the third film improves hardness. This segmentation allows the system to achieve both strength and toughness that a single material cannot provide.
Solution Approach 2:
Each film layer in the laminated structure serves multiple functions: providing mechanical protection, enhancing toughness, maintaining optical transparency, and contributing to overall flexibility. This multi-functionality allows the system to meet diverse performance requirements without significantly complicating the manufacturing process.
Data Source
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AI summary
Disclosed are a laminated film including a first film disposed on a front surface of a display panel of a display device and a second film disposed on the first film, wherein a tensile modulus of the second film is greater than or equal to a tensile modulus of the first film, and a transmittance of the first film is greater than or equal to a transmittance of the second film, provided that at least one of the tensile modulus of the first film and the tensile modulus of the second film are not equal or the transmittance of the first film and the transmittance of the second film are not equal.