Selective Photoinitiator Curing for Flexible Display Adhesion
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Solution Overview
Problem
Existing display devices face challenges in manufacturing flexible, bended displays with strong adhesion between the display module and the window, particularly in ensuring uniform curing and high durability.
Innovation Solution
A display device is designed with a window having a bending area and a non-bending area, an adhesive layer with distinct photoinitiator-cured resin portions for each area, and a display module. The adhesive layer includes a first adhesive portion cured with a first photoinitiator responsive to a specific light and a second adhesive portion cured with a second photoinitiator responsive to a different light or thermal initiator, ensuring differential curing and strong adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single adhesive layer is used for both bending and non-bending areas, then the manufacturing process is simple, but the adhesion strength and durability are insufficient in the bending area
Solution Approach 1:
The adhesive layer is divided into multiple regions with different photoinitiators: a first adhesive region containing a first photoinitiator responsive to first light, and a second adhesive region containing a second photoinitiator responsive to second light. This segmentation allows each region to be optimized for its specific function, with the first region providing strong adhesion in the bending area and the second region providing adhesion in the non-bending area.
Solution Approach 2:
Different photoinitiators are used in different regions of the adhesive layer to create local quality variations. The first photoinitiator is specifically activated by first light in the bending area to provide enhanced adhesion, while the second photoinitiator is activated by second light in the non-bending area. This local differentiation ensures optimal adhesion performance in each specific region.
2Ease of manufacture
If conventional curing methods are used, then the process is simple, but uniform curing across bending and non-bending areas cannot be achieved
Solution Approach 1:
The curing process is segmented into multiple stages using different light sources. First light is used to cure the first photoinitiator in the bending area, and second light is used to cure the second photoinitiator in the non-bending area. This segmentation enables uniform curing in each region by using photoinitiators that are specifically responsive to their respective light wavelengths.
Solution Approach 2:
The curing process utilizes parameter changes by employing photoinitiators with different spectral responses. The first photoinitiator is selected to be responsive to first light with specific wavelength characteristics, while the second photoinitiator is responsive to second light with different wavelength characteristics. This parameter differentiation allows precise control over curing uniformity in different regions.
3Reliability
If multiple adhesive layers with different photoinitiators are used, then adhesion durability is improved, but the device complexity increases
Solution Approach 1:
Multiple adhesive regions with different photoinitiators are merged into a single continuous adhesive layer. The first adhesive region and second adhesive region are disposed adjacent to each other within the same adhesive layer, eliminating the need for separate adhesive layers while maintaining the benefits of differentiated adhesion properties.
Solution Approach 2:
The single adhesive layer serves multiple functions by incorporating different photoinitiators in different regions. It provides both bending area adhesion through the first photoinitiator and non-bending area adhesion through the second photoinitiator, making the adhesive layer multi-functional and reducing overall device complexity.
4Productivity
If conventional single-step curing is used, then the process is fast, but adhesion strength in bending areas is insufficient
Solution Approach 1:
The curing process is segmented to apply different light sources at different times or in different sequences. The first light cures the first photoinitiator to provide strong adhesion in the bending area, while the second light cures the second photoinitiator for the non-bending area. This segmentation ensures that adhesion strength requirements are met while maintaining overall curing efficiency.
Solution Approach 2:
The first photoinitiator is designed to be cured by first light before or during the curing of the second photoinitiator by second light. This preliminary action ensures that the bending area, which requires stronger adhesion, is cured first or simultaneously, providing the necessary bond strength early in the process.
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 achieves high durability and visibility by ensuring strong adhesion between the display module and the window, while reducing process costs and time through selective curing without the need for a separate mask.
Implementation Method 1
the first adhesive portion is formed by curing a first resin including a first photoinitiator configured to have an initiation reaction induced by a first light
Implementation Method 2
the second adhesive portion is formed by curing a second resin including a second photoinitiator configured to have an initiation reaction induced by a second light
Implementation Method 3
a second photoinitiator configured to have an initiation reaction induced by a second light or a thermal initiator
Data Source
AI summary
A display device includes: a window including a bending area and a non-bending area; an adhesive layer including a first adhesive portion and a second adhesive portion, wherein the first adhesive portion overlaps the bending area, and the second adhesive portion overlaps the non-bending area; and a display module disposed on the adhesive layer, wherein the first adhesive portion is formed by curing a first resin including a first photoinitiator configured to have an initiation reaction induced by a first light, and the second adhesive portion is formed by curing a second resin including a second photoinitiator configured to have an initiation reaction induced by a second light or a thermal initiator, wherein the second light has a different central wavelength from that of the first light.