Photo-Aligned Liquid Crystal Display Alignment Layer UV Wavelength Control
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Solution Overview
Problem
Current methods for forming alignment layers in liquid crystal displays, such as rubbing and photo-alignment, face challenges in achieving optimal pretilt angles and voltage holding ratios, leading to issues like image sticking and reduced display quality.
Innovation Solution
A method involving the formation of alignment layers using a photo-alignment process with a specific wavelength of ultraviolet light (280-340 nanometers) to align liquid crystal molecules, reducing image sticking and improving pretilt angles and voltage holding ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rubbing method is used to form alignment layer, then liquid crystal molecules can be initially aligned, but image sticking occurs and voltage holding ratio decreases
Solution Approach 1:
The patent replaces the mechanical rubbing method with a photo-alignment method using ultraviolet light irradiation. The alignment layer is formed by coating an alignment solution containing photoreactive groups, baking it, and then irradiating with UV light to induce photo-dimerization or photo-isomerization, which creates the alignment structure without mechanical contact, thereby eliminating image sticking while maintaining proper liquid crystal alignment
Solution Approach 2:
The patent changes the chemical parameters of the alignment layer by introducing specific photoreactive groups (cinnamate groups, coumarin groups, or oxa-diazole groups) that undergo photochemical reactions when irradiated with UV light of specific wavelengths (280-340 nm), transforming the alignment mechanism from mechanical to photochemical and improving voltage holding ratio while preventing image sticking
2Ease of operation
If conventional photo-alignment method is used, then alignment layer can be formed without rubbing, but pretilt angle control is insufficient
Solution Approach 1:
The patent achieves precise pretilt angle control by changing the chemical structure parameters of the photoreactive groups in the alignment solution. Specific groups (cinnamate, coumarin, oxa-diazole) with defined molecular structures and photochemical properties are selected to achieve predetermined pretilt angles, allowing accurate control of liquid crystal molecule orientation without mechanical rubbing
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 method enhances display quality by reducing image sticking, improving pretilt angle stability, and maintaining voltage holding ratios, thereby minimizing faults like beating texture in liquid crystal displays.
Implementation Method 1
The photo reactive group may be a crosslinking reactive group which causes a photo dimerization or a photo isomerization with a reactive group adjacent thereto when the light is irradiated.
Implementation Method 2
The photo reactive group may be a crosslinking reactive group which causes a photo dimerization or a photo isomerization with a reactive group adjacent thereto when the light is irradiated.
Data Source
AI summary
An alignment layer is formed by forming an alignment solution on a base substrate, baking the alignment solution to form an alignment layer, and irradiating light having a wavelength of about 280 nanometers to about 340 nanometers to the alignment layer, thereby aligning the alignment layer. A liquid crystal display is manufactured using the method of forming the alignment layer.