Conductive Alignment Layer for LCD Substrates
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Solution Overview
Problem
The manufacturing process of conductive and alignment layers in Thin Film Transistor Liquid Crystal Display (TFT-LCD) substrates is complex due to the fragile nature of ITO conductive layers and the inefficiencies in rubbing-based alignment processes, which can lead to uneven alignment and contamination, and are not suitable for advanced production lines.
Innovation Solution
A conductive alignment layer comprising a combination of conductive and alignment materials, such as carbon nanotubes, metal nanostructured materials, and photosensitive molecules, is used to simplify the manufacturing process by integrating conductivity and alignment capabilities into a single layer, reducing the need for separate conductive and alignment layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO is used as the common electrode to provide conductivity, then electrical conductivity is achieved, but the layer becomes fragile and liable to detach from the CF layer
Solution Approach 1:
The patent uses a composite material comprising carbon nanotubes dispersed in a polyimide matrix to create the conductive alignment layer. This composite provides both electrical conductivity (from carbon nanotubes) and mechanical strength with good adhesion (from polyimide), replacing the fragile ITO layer while maintaining the required electrical properties and improving mechanical reliability.
2Reliability
If a transparent conductive film is prepared by sputtering at high temperature to improve conductivity, then electrical conductivity is enhanced, but the CF layer may be damaged
Solution Approach 1:
The patent changes the temperature parameter from high temperature sputtering to low temperature solution processing. The conductive alignment layer is formed by coating a solution containing carbon nanotubes and polyimide, then drying and curing at relatively low temperatures, which avoids thermal damage to the CF layer while still achieving the required electrical conductivity through the carbon nanotube network.
3Manufacturing precision
If rubbing with cotton cloth or nylon cloth is used to align the polyimide film, then alignment is achieved, but uneven rubbing effect and contamination of liquid crystals occur
Solution Approach 1:
The patent replaces the mechanical rubbing system with a photoalignment system. Instead of using friction from cotton or nylon cloth to align the polyimide molecules, the patent incorporates photosensitive alignment molecules that, when exposed to polarized light, create a uniform alignment pattern without physical contact. This eliminates contamination risks and achieves more uniform alignment.
4Ease of operation
If a friction roller is used in the rubbing alignment process to achieve alignment, then alignment function is provided, but the roller cannot work properly in advanced production lines due to its large weight
Solution Approach 1:
The patent replaces the heavy mechanical friction roller system with a lightweight photoalignment approach using polarized light exposure. The alignment is achieved through optical fields acting on photosensitive molecules rather than mechanical friction, making the process compatible with advanced production lines that cannot accommodate heavy rollers while maintaining effective alignment functionality.
5Reliability
If separate conductive layer and alignment layer are formed to provide respective functions, then functional performance is achieved, but the manufacturing process becomes complicated
Solution Approach 1:
The patent merges the conductive layer and alignment layer into a single integrated conductive alignment layer. By incorporating carbon nanotubes (providing conductivity) into a polyimide matrix with photosensitive alignment molecules (providing alignment function), the patent achieves both electrical conductivity and liquid crystal alignment in one layer, significantly simplifying the manufacturing process while maintaining the functional performance of both separate layers.
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 approach simplifies the manufacturing process by enabling simultaneous formation of conductive and alignment layers, improving conductivity and alignment while reducing the complexity and potential issues associated with traditional methods, such as fragile ITO layers and uneven rubbing effects.
Implementation Method 1
a conductive material and an alignment material; or, a conductive alignment material. The conductive alignment layer is configured to possess both conductivity and alignment
Implementation Method 2
the photosensitive alignment molecule is selected from a group consisted of photoisomerized azobenzene group, photodimerized cinnamic acid ester
Implementation Method 3
the photosensitive alignment molecule is selected from a group consisted of photoisomerized azobenzene group, photodimerized cinnamic acid ester
Data Source
AI summary
Disclosed are a conductive alignment layer, a manufacture method of the conductive alignment layer, a display substrate comprising the conductive alignment layer and a display device which relate to the technology of LCD, simplify the manufacture method of conductive layer and alignment layer and also reduce the complexity in manufacturing a LCD device by preparing the conductive layer and the alignment layer in the substrate simultaneously through utilizing a material possessing both conductivity and alignment, without the need of preparing the conductive layer and the alignment layer separately.