Multilayer Optical Bonding for LCD Mura Reduction
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Solution Overview
Problem
Inconsistent gaps between the display and liquid crystal drive substrates in LCDs lead to stress, causing variations in the liquid crystal layer thickness and resulting in the mura phenomenon, which is exacerbated by the integration of touch-sensitive technology.
Innovation Solution
An optical bonding apparatus with a multiple layer structure, comprising a pressure sensitive bonding layer and a thermal flow pressure sensitive bonding layer, is used to bond between the touch panel and LCD, ensuring even surfaces and reducing stress through the thermal flow pressure sensitive bonding layer's ability to fill rough surfaces and maintain evenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bonding layer is used between the touch panel and LCD, then the device structure is simple, but the bonding surface remains rough and causes uneven spacing leading to mura phenomenon
Solution Approach 1:
The bonding layer is divided into multiple sub-layers: a first bonding layer in contact with the LCD and a second bonding layer in contact with the touch panel. This segmentation allows each layer to perform specific functions - the first layer provides initial bonding while the second layer with higher viscosity fills surface irregularities, achieving both structural simplicity and spacing precision.
Solution Approach 2:
The bonding apparatus uses composite bonding layers with different material properties. The first bonding layer has lower viscosity for initial bonding, while the second bonding layer has higher viscosity to maintain spacing and fill rough surfaces. This composite structure combines the advantages of different materials to achieve both ease of application and precise spacing control.
2Manufacturing precision
If the bonding layer fills rough surfaces to ensure even spacing, then the mura phenomenon is reduced, but the bonding process becomes more complex
Solution Approach 1:
Different regions of the bonding layer have different viscosities tailored to their specific functions. The first bonding layer has lower viscosity to flow and bond to the LCD surface, while the second bonding layer has higher viscosity to fill rough areas and maintain uniform spacing. This local differentiation of material properties achieves precise thickness control without excessive structural complexity.
3Strength
If pressure is applied to ensure bonding, then adhesion strength is improved, but the liquid crystal layer thickness varies causing mura
Solution Approach 1:
The bonding layers are designed to perform preliminary actions in sequence: the first bonding layer initially bonds to the LCD surface, then the second bonding layer with higher viscosity fills surface irregularities and maintains spacing before final bonding completion. This preliminary action sequence ensures both strong bonding and uniform liquid crystal layer thickness.
Solution Approach 2:
The second bonding layer with higher viscosity acts as a cushioning layer that compensates for surface roughness and prevents excessive pressure transmission to the liquid crystal layer. This beforehand cushioning protects the liquid crystal layer from thickness variations while still allowing adequate bonding pressure to be applied.
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 effectively reduces or eliminates the mura phenomenon by ensuring even spacing between the LCD and touch panel, enhancing display quality and consistency.
Implementation Method 1
a thermal flow pressure sensitive bonding layer, which is used for bonding to a rough surface of an object
Implementation Method 2
a pressure sensitive bonding layer and a thermal flow pressure sensitive bonding layer
Data Source
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AI summary
An optical bonding apparatus (30) with multilayer structure includes a pressure sensitive bonding layer (310) and a thermal flow pressure sensitive bonding layer (320). The thermal flow pressure sensitive bonding layer (320) is bonded to a rough surface of an object and superposed on the pressure sensitive bonding layer (310).