Multi-layer Polymeric Protective Sheets for Non-planar Display Surfaces
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Solution Overview
Problem
Conventional glass screen protectors for electronic devices lack flexural integrity, making them difficult to apply and maintain on non-planar surfaces, and more rigid films that provide adequate protection are often deficient in adherence due to their inability to form and maintain the shape of curved surfaces.
Innovation Solution
A multi-layer polymeric protective sheet with a modifiable interlayer that can be shaped into a non-planar form and subsequently modified to increase its shear storage modulus for durable adherence and protection, combining the flexibility to form into desired shapes with the rigidity needed for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If glass sheets are used for screen protection, then a more natural feel is provided, but flexural integrity is insufficient making application difficult
Solution Approach 1:
The patent uses a multi-layer composite structure combining a first polymeric layer, a second polymeric layer, and a glass sheet. This composite design allows the glass to provide natural feel while the polymeric layers provide flexibility and formability, resolving the contradiction between feel and flexural integrity.
Solution Approach 2:
The patent employs polymeric film layers that are flexible and formable into non-planar shapes, allowing the screen protector to conform to curved surfaces while maintaining the glass sheet's natural feel property.
2Strength
If more rigid films are used for protection, then adequate protection is provided, but adherence to curved surfaces is deficient
Solution Approach 1:
The patent combines rigid glass sheet with flexible polymeric layers to create a composite structure that provides both protection and adherence to curved surfaces. The polymeric layers conform to the surface geometry while the glass provides protective strength.
Solution Approach 2:
The patent utilizes the glass transition temperature parameter to control the flexibility of polymeric layers. By selecting polymers with appropriate Tg values, the film remains flexible at application temperature for good adherence, then sets to provide rigid protection during use.
3Adaptability or versatility
If conventional polymeric films are used, then flexibility and formability are adequate, but protective strength is insufficient
Solution Approach 1:
The patent creates a multi-layer composite where flexible polymeric layers provide formability and adherence, while the embedded glass sheet provides the necessary protective strength, achieving both formability and protection simultaneously.
Solution Approach 2:
The patent divides the screen protector into separate functional layers: outer and inner polymeric layers for flexibility and adherence, with a central glass sheet for protection. This segmentation allows each layer to optimize its specific function.
4Ease of operation
If glass sheets are applied to non-planar surfaces, then natural feel is maintained, but edge lift occurs due to spring back
Solution Approach 1:
The patent uses flexible polymeric layers as bookends to the glass sheet, creating a composite that maintains natural feel while the polymeric outer layers prevent edge lift by conforming to curved surfaces without spring back.
Solution Approach 2:
The patent employs flexible polymeric film layers that can permanently deform to match non-planar surface geometry, preventing the spring back effect that causes edge lift in rigid glass sheets applied to curved surfaces.
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 allows for a protective sheet that is both flexible enough to form into non-planar shapes and rigid enough to provide adequate protection, maintaining the shape and adhering well to curved surfaces, addressing the shortcomings of conventional glass and polymeric films.
Implementation Method 1
heating the multi-layer protective sheet to a temperature above a glass transition temperature of the modifiable interlayer, thereby decreasing a shear storage modulus of the modifiable interlayer
Implementation Method 2
irradiating the multi-layer protective sheet with UV light, thereby initiating curing of the modifiable interlayer
Data Source
AI summary
Multi-layer protective sheets of the invention are both rigid enough to provide desired protective properties, but flexible enough to be formable into a desired non-planar shape in order to protect surfaces such as optical display surfaces of electronic devices. Once formed into the desired non-planar shape, a modified interlayer of the multi-layer protective sheet has a shear storage modulus of greater than about 100 MPa.