IPS LCD Orientation Film Thermal Stability
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Solution Overview
Problem
The existing photo-alignment methods for liquid crystal display devices, such as those using polyvinyl cinnamate and specific polyimides, face issues with thermal stability and reliability, leading to unsatisfactory temporal liquid crystal alignment and image persistence problems, particularly in large-scale IPS-TFT-LCDs with narrow manufacturing margins.
Innovation Solution
The use of photosensitive polyimide and polyamide acid ester materials for orientation control films, which are treated with almost linearly polarized light to improve thermal stability and reduce thermal depolymerization, thereby enhancing the stability of liquid crystal orientation and suppressing image persistence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photo-alignment methods using polyvinyl cinnamate or specific polyimides are used, then the orientation control film can be formed, but thermal stability is insufficient and thermal depolymerization occurs leading to image persistence
Solution Approach 1:
The patent changes the chemical composition parameters of the orientation control film by using photosensitive polyimide and polyamide acid ester materials instead of conventional polyvinyl cinnamate or specific polyimides. This material substitution fundamentally alters the thermal properties, raising the decomposition temperature and eliminating thermal depolymerization while maintaining photo-alignment functionality.
Solution Approach 2:
The patent employs composite material strategy by combining photosensitive polyimide and polyamide acid ester in specific formulations. These composite materials integrate the advantages of both polymer types, achieving superior thermal stability and resistance to thermal depolymerization while maintaining the necessary optical and alignment properties for liquid crystal orientation control.
2Ease of operation
If the orientation control film is made photosensitive for photo-alignment treatment, then liquid crystal orientation can be controlled, but image persistence problems occur due to thermal depolymerization
Solution Approach 1:
The patent modifies the chemical structure parameters of the orientation control film materials to incorporate photosensitive groups within the polyimide and polyamide acid ester frameworks. This enables the materials to respond to polarized light for precise liquid crystal orientation control while the inherent thermal stability of these polymers prevents the image persistence problem that plagues conventional materials.
3Manufacturing precision
If large-scale IPS-TFT-LCDs are manufactured with narrow manufacturing margins, then high definition images can be achieved, but alignment stability deteriorates due to thermal depolymerization
Solution Approach 1:
The patent fundamentally changes the thermal decomposition parameters of the orientation control film by selecting polyimide and polyamide acid ester materials with inherently high thermal stability. This allows the film to withstand the narrow manufacturing margins and precise alignment requirements of large-scale IPS-TFT-LCDs without undergoing thermal depolymerization, thereby maintaining alignment stability and achieving high definition images.
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 results in higher contrast ratio and definition images with reduced defective displays due to improved alignment stability, enabling mass production of high-image-quality liquid crystal display devices with faster image sticking fading times.
Implementation Method 1
an orientation control film disposed on at least one of the pair of substrates, wherein at least one of the orientation control film is made of photosensitive polyimide and polyamide acid ester and is given orientation control ability by being irradiated with almost linearly polarized light
Data Source
AI summary
An IPS type liquid crystal display device superior in mass productivity and improved in image quality with a higher contrast ratio by decreasing the occurrence of defective display due to the disorder of the initial liquid crystal alignment by the liquid orientation control film and realizing stable alignment of liquid crystals comprises: a pair of substrates, at least one which is transparent; a liquid crystal layer disposed between the pair of substrates; a group of electrodes formed on at least one of the pair of substrates to apply an electric field to the liquid crystal layer; plural active elements connected to the group of electrodes; and an orientation control film disposed on at least one of the pair of substrates, wherein said orientation control film is made of a photosensitive polyimide and a polyamide acid ester and is given orientation control ability by being irradiated with substantially linearly polarized light.