Liquid Crystal Display Orientation Control Without Alignment Film
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Solution Overview
Problem
Liquid crystal display devices face issues with image sticking and droplet stains during production, which are not effectively addressed by existing technologies, and these defects impact the display's performance and quality.
Innovation Solution
A liquid crystal display device is developed using a liquid crystal composition with specific compounds represented by General Formulae (I) and (II), combined with two or more polymerizable compounds, which are polymerized between substrates without an alignment film, to create orientation controlling layers and provide a pretilt angle to the liquid crystal molecules, reducing image sticking and droplet stains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If protrusions are formed on substrate to enable multi-directional liquid crystal orientation (MVA), then viewing angle characteristics are improved, but response speed becomes insufficient and light transmittance decreases
Solution Approach 1:
The invention extracts and removes the protrusions from the substrate structure. Instead of using protrusions to control liquid crystal orientation, the patent employs a different approach where liquid crystal molecules are directly oriented on the substrate surface without any protruding structures, thereby eliminating the light blocking issue and improving response speed while maintaining viewing angle characteristics
Solution Approach 2:
The invention inverts the conventional MVA approach by not using protrusions to create multi-domain orientation. Instead, it uses a flat substrate with liquid crystal molecules oriented in multiple directions through alternative means (such as rubbing or photoalignment), achieving the same viewing angle improvement without the harmful effects of protrusions
2Speed
If polymerizable compound is added to liquid crystal composition for PSA to give even pretilt angle, then light transmittance and response speed are enhanced, but image sticking occurs in active-matrix displays
Solution Approach 1:
The invention extracts and removes the polymerizable compound from the liquid crystal composition. By eliminating the polymerization process, the patent prevents image sticking while maintaining response speed through alternative orientation control methods that do not rely on polymer networks
Solution Approach 2:
The invention changes the fundamental parameter of the liquid crystal composition by removing polymerizable compounds. This parameter change eliminates the side reactions and image sticking problems associated with polymerization, while response speed is maintained through optimized liquid crystal material selection and orientation control techniques
3Manufacturing precision
If alignment film is formed on substrate, then liquid crystal orientation is controlled, but manufacturing complexity increases and defects may occur
Solution Approach 1:
The invention extracts and removes the alignment film layer from the substrate structure. By eliminating this additional layer, the patent simplifies the manufacturing process and reduces potential defect sources while maintaining precise liquid crystal orientation control through direct substrate surface treatment or alternative alignment methods
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 image sticking and droplet stains while maintaining the essential properties of dielectric anisotropy, viscosity, and rotational viscosity, enhancing the display's contrast and response speed.
Implementation Method 1
polymerizing the polymerizable compounds in the liquid crystal composition by irradiation with an active energy ray under application of voltage between electrodes
Data Source
AI summary
A liquid crystal display device which enables reductions in image sticking and droplet stains caused in production thereof without degradation of properties such as dielectric anisotropy, viscosity, the upper limit of the temperature of nematic phase, and rotational viscosity (γ1); and a method for manufacturing such a liquid crystal display device. The liquid crystal display device is characterized in that a liquid crystal layer containing a liquid crystal composition is disposed between a substrate provided with a common electrode and a color filter layer and another substrate provided with a plurality of pixels each having a pixel electrode, each of the substrates is not provided with an alignment film but provided with an orientation controlling layer composed of at least two polymerizable compounds, each of the pixels has two or more regions having different directions of pretilt, and the liquid crystal composition contains a compound represented by General Formula (I) and a compound represented by General Formula (II).