Hybrid Flexible Cover Window for UV-Cured Foldable Displays
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Solution Overview
Problem
Existing flexible cover windows made of polyimide (PI) suffer from weak mechanical strength, poor impact resistance, low transmittance, and delamination issues, especially when folded, and incomplete adhesive curing due to UV blocking, leading to reduced lifespan.
Innovation Solution
A flexible hybrid cover window combining a glass substrate with a transparent polyimide (TPI) layer and an adhesive buffer layer, where the TPI layer has a UV cut-off wavelength of less than 380 nm, allowing complete adhesive curing and enhanced bonding, and a composite structure that includes a functional layer for improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polymer film made of polyimide (PI) is used as a flexible cover window, then flexibility is achieved, but mechanical strength and impact resistance are weak
Solution Approach 1:
The patent combines glass substrate with transparent polyimide (TPI) layer to create a hybrid cover window structure. The glass provides mechanical strength and impact resistance, while the TPI layer maintains flexibility and optical transparency. This composite structure resolves the contradiction by integrating materials with complementary properties.
2Strength
If the thickness of the cover window is increased to improve strength, then mechanical strength improves, but deformation upon bending increases causing delamination and buckling
Solution Approach 1:
The patent changes the material parameters by using transparent polyimide (TPI) with specific optical properties (UV cut-off wavelength less than 380 nm) instead of conventional PI. The TPI layer thickness is optimized to balance strength and flexibility, allowing the cover window to maintain structural integrity while reducing deformation during folding.
3Ease of manufacture
If a conventional polyimide film is used, then flexibility is achieved, but UV curing of adhesive layer is blocked leading to incomplete curing and reduced lifespan
Solution Approach 1:
The patent modifies the optical parameters of the polyimide material by selecting TPI with a UV cut-off wavelength of less than 380 nm. This parameter change allows UV light to penetrate through the cover window for complete adhesive curing, while the material still provides the required flexibility and mechanical properties.
4Object-affected harmful factors
If the hardness of the cover window is increased to improve durability, then impact resistance improves, but deformation upon bending increases making the cover window difficult to apply
Solution Approach 1:
The patent creates a composite structure where glass substrate provides hardness and impact resistance, while the TPI layer maintains flexibility. The layered composite allows the system to exhibit both high durability and folding flexibility that neither material could achieve alone.
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 provides a durable, impact-resistant cover window with complete adhesive curing, maintaining image quality and reducing deformation, while accommodating various product structures and improving overall durability and folding characteristics.
Implementation Method 1
the TPI layer has a UV cut-off wavelength of less than 380 nm
Implementation Method 2
curing the adhesive buffer layer by applying ultraviolet rays
Data Source
AI summary
Proposed are a hybrid flexible cover window and a method of manufacturing the same. The hybrid flexible cover window includes a flat portion formed on a flat area of a flexible display and a folding portion which is formed in succession to the flat portion and formed in a folding area of the flexible display. The hybrid flexible cover window includes a substrate, a transparent polyimide layer formed on the glass substrate, and an adhesive buffer layer formed between the glass substrate and the TPI layer, in which the TPI layer has a UV cut-off wavelength of less than 380 nm.