Bonding Member Modulus Control for Display Air Bubble Reduction
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Solution Overview
Problem
Display devices often suffer from air bubbles trapped in the bonding member between the display panel and the cover window, which can constrain the design and functionality of the device.
Innovation Solution
A display device design featuring a bonding member with a modulus that increases as temperature and pressure increase, combined with a printed pattern that extends from the cover window and overlaps the display panel, reduces air bubbles by efficiently absorbing height differences and preventing external air permeation during the autoclave process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bonding member is used to bond the display panel and cover window, then the components are securely joined, but air bubbles become trapped in the bonding member
Solution Approach 1:
The bonding member's modulus is dynamically changed during the bonding process. At room temperature, the bonding member has low modulus (about 100 kPa to about 200 kPa) to allow air bubbles to escape. During autoclaving at 60-80°C and 6-8 bars pressure, the modulus increases to about 800 kPa to about 1000 kPa to prevent external air permeation and maintain bonding strength.
Solution Approach 2:
The bonding member is designed to undergo preliminary softening at room temperature before bonding, allowing air bubbles to be expelled during the initial bonding process. The printed pattern is also positioned in advance to overlap the display panel, creating a barrier that prevents air bubble formation during subsequent autoclaving.
2Object-generated harmful factors
If the bonding member has low modulus to reduce air bubbles, then air bubble permeation is reduced, but adhesive characteristics are compromised
Solution Approach 1:
The bonding member exhibits dynamic mechanical properties that change with temperature and pressure. The modulus transitions from a soft state (100-200 kPa at room temperature) that allows air bubble expulsion to a rigid state (800-1000 kPa at autoclaving conditions) that maintains bonding strength and prevents air permeation.
Solution Approach 2:
The physical parameters of the bonding member are changed during processing. The temperature-dependent modulus transformation allows the material to adapt its properties: soft and permeable at room temperature for air bubble removal, then rigid and impermeable during autoclaving to maintain adhesive characteristics.
3Object-generated harmful factors
If the bonding member is designed to prevent air bubbles, then air bubble formation is reduced, but the processing complexity increases
Solution Approach 1:
The bonding member automatically adjusts its modulus in response to temperature and pressure changes during the bonding process. This self-regulating behavior eliminates the need for complex external control systems or multiple processing steps, as the material inherently transitions from a bubble-expelling soft state to a bubble-preventing rigid state.
Solution Approach 2:
The printed pattern serves as an intermediary element that extends from the cover window and overlaps the display panel. This intermediate structure helps guide the bonding process and prevents air bubble formation by creating a controlled interface between components, simplifying the overall bonding procedure.
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
This solution effectively minimizes air bubbles, maintaining adhesive characteristics and reducing the bezel area, while simplifying processing and eliminating the need for separate post-curing, thus enhancing the display device's performance and appearance.
Implementation Method 1
the bonding member has a modulus that increases as a temperature increases
Implementation Method 2
the bonding member has a modulus of about 800 kilopascals (kPa) to about 1000 kPa under conditions of a temperature ranging from about 60 degrees Celsius (° C.) to about 80° C. and a pressure ranging from about 6 bars to about 8 bars
Data Source
AI summary
A display device includes a flat portion defined by a first direction and a second direction crossing the first direction, a bent portion disposed on at least one side of the flat portion and bent in a third direction perpendicular to the first and second directions, a display panel disposed over the flat portion and the bent portion, a cover window disposed on the display panel and disposed over the flat portion and the bent portion, and a bonding member disposed between the display panel and the cover window, where the bonding member has a modulus that increases as a temperature increases.