Embossed Alignment Film via Soft Mold UV Exposure
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Solution Overview
Problem
Conventional methods for fabricating alignment films in liquid crystal display panels, such as rubbing and ultraviolet radiation, either cause physical damage or result in low liquid crystal alignment forces, leading to defects and reduced contrast ratios.
Innovation Solution
A method involving a soft mold with a concavo-convex pattern is used to expose photosensitive alignment material to ultraviolet radiation, creating an embossed alignment film that mimics the structure of rubbing films without physical damage, enhancing the alignment force with liquid crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a rubbing process is used to form the alignment film, then the alignment force for liquid crystal is improved, but physical defects such as scratches and vertical lines are generated in the alignment film
Solution Approach 1:
The patent replaces the mechanical rubbing process with a photoalignment process using ultraviolet radiation. Instead of using a rubbing cloth to create alignment grooves physically, the invention uses UV light to induce molecular reorientation in a photosensitive alignment material, achieving the same alignment effect without mechanical contact and associated defects
Solution Approach 2:
The patent changes the method of creating alignment grooves from mechanical deformation to photochemical transformation. By controlling UV radiation exposure parameters (wavelength, intensity, duration) and the photosensitive material composition, the alignment film creates the necessary surface grooves and molecular orientation without physical rubbing, thereby eliminating scratches and vertical lines
2Object-affected harmful factors
If ultraviolet radiation is used to form the alignment film, then physical defects are prevented, but the alignment force for liquid crystal is reduced
Solution Approach 1:
The patent employs a composite approach by combining a photosensitive alignment material with specific molecular structures that enhance liquid crystal interaction. The alignment material contains photoactive compounds that, when exposed to UV radiation, create both the structural grooves and the chemical alignment fields necessary for strong liquid crystal alignment, thereby maintaining high alignment force without mechanical rubbing
Solution Approach 2:
The patent enhances the alignment force by utilizing the molecular orientation dimension created through photoalignment. Instead of relying solely on surface topography from rubbing, the UV-exposed photosensitive material creates molecular-level alignment fields that extend into the liquid crystal layer, providing stronger and more uniform alignment force without physical defects
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 prevents physical defects and improves the alignment force for liquid crystals, resulting in higher contrast ratios and better image quality compared to traditional methods.
Implementation Method 1
a light irradiation device operative to expose the alignment material to ultraviolet radiation through the soft mold
Data Source
AI summary
An alignment film and method of fabricating the alignment film are disclosed. A photosensitive alignment material is spread on an LCD array substrate or color filter substrate and partially cured. A soft mold is aligned on the partially cured alignment material. The soft mold has a concavo-convex pattern with grooves and projections. The alignment material is exposed to ultraviolet radiation through the soft mold and then developed. The differences between the indices of refraction of the soft mold and air cause interference in the ultraviolet radiation, leading to periodic variations in the exposure intensity of the alignment material. These variations result in crests and troughs being formed when the alignment film is developed. The developed alignment film is then cured.