Adhesive Storage Modulus Control for Foldable Display Reliability
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Solution Overview
Problem
Foldable or rollable display devices are prone to damage when bent or rolled, and existing adhesive layers can generate residues that harm the window, leading to instability and potential damage.
Innovation Solution
A display device with an anti-reflective layer and adhesive layers having a specific storage modulus change rate at varying temperatures, ensuring minimal residue generation and structural integrity during folding, along with a manufacturing method involving a laser beam cutting process to align and attach components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional adhesive layer is used to attach the window to the anti-reflective layer, then adhesion is achieved, but adhesive residues are generated at high temperatures causing window damage and reliability issues
Solution Approach 1:
The patent applies parameter changes by selecting an adhesive with specific storage modulus characteristics that change minimally (change rate of 0.3 or less) between 60°C and 150-200°C. This parameter selection ensures the adhesive maintains stable physical properties across the temperature range encountered during device operation and manufacturing, preventing residue generation while preserving adhesion functionality.
Solution Approach 2:
The patent applies local quality by specifying particular storage modulus values for the adhesive at different temperatures (about 10-50 Kpa at 60°C, and maintaining stability up to 150-200°C). This creates locally optimized adhesive properties that prevent harmful residue generation at the window-adhesive interface while ensuring adequate adhesion strength at operating temperatures.
2Adaptability or versatility
If the display device is folded or rolled to improve portability, then user convenience is enhanced, but component damage occurs due to mechanical stress
Solution Approach 1:
The patent applies parameter changes by selecting an adhesive with storage modulus of about 10-50 Kpa at 60°C that maintains stability up to 150-200°C. This ensures the adhesive remains flexible enough to accommodate folding/rolling mechanical stresses while maintaining sufficient bond strength to prevent component separation or damage during portability operations.
Solution Approach 2:
The patent applies beforehand cushioning by using an adhesive layer with optimized storage modulus characteristics that anticipates and cushions against the mechanical stresses of folding and rolling. The adhesive's physical properties are pre-selected to absorb and distribute stress during bending operations, preventing damage before it occurs to the window and other components.
3Ease of operation
If the adhesive storage modulus changes significantly at high temperatures, then adhesion flexibility increases, but residue generation increases causing window damage
Solution Approach 1:
The patent applies parameter changes by inverting the conventional approach: instead of allowing large storage modulus changes for adhesion flexibility, it selects an adhesive with minimal storage modulus change (change rate of 0.3 or less) between 60°C and 150-200°C. This parameter optimization achieves both adequate adhesion flexibility at operating temperatures and minimal residue generation at elevated temperatures during manufacturing or operation.
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 prevents window damage and reduces adhesive residue formation, enhancing the folding reliability and stability of the display device while maintaining effective adhesion and structural alignment.
Implementation Method 1
The first adhesive layer includes an adhesive having a change rate in a storage modulus of about 0.3 or less at a temperature of about 150 degrees Celsius (° C.) to about 200° C. with respect to the storage modulus at a temperature of about 60° C.
Implementation Method 2
cutting the display panel and the first stack structure attached to the display panel using a laser beam
Data Source
AI summary
A display device includes a display panel folded with respect to an imaginary folding axis extending in a first direction, an anti-reflective layer disposed on the display panel, a window disposed on the anti-reflective layer, and a first adhesive layer disposed between the anti-reflective layer and the window. The first adhesive layer includes an adhesive having a change rate in a storage modulus of about 0.3 or less at a temperature of about 150 degrees Celsius (° C.) to about 200° C. with respect to the storage modulus at a temperature of about 60° C.