Liquid Crystal Display Pre-tilt Alignment via Thermal Field
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing liquid crystal display devices in the VA mode face challenges in improving response characteristics due to the need for elaborate apparatuses and complex manufacturing processes, particularly when using photo-alignment techniques for multi-domain types, which also result in degraded response characteristics due to twisted liquid crystal molecule alignments.
Innovation Solution
A liquid crystal display device with an array of pixels featuring first and second substrates, electrodes, alignment films, and a liquid crystal layer where the major axes of liquid crystal molecules are positioned in the same imaginary plane, with pre-tilt given by the alignment films, allowing for improved response characteristics without requiring elaborate apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If photo-alignment technique is used to give pre-tilt to liquid crystal molecules, then response characteristic is improved, but manufacturing process becomes complex and elaborate light irradiation apparatus is required
Solution Approach 1:
The patent replaces the complex optical system (linearly-polarized light irradiation apparatus) with a simple thermal field application system. By applying a thermal field to the isotropic liquid crystal composition containing photo-reactive alignment groups, the alignment is achieved without requiring elaborate light irradiation equipment, thus substituting a mechanical/optical system with a simpler thermal field system.
Solution Approach 2:
The patent changes the physical-chemical parameters of the liquid crystal system by using an isotropic liquid crystal composition with photo-reactive alignment groups instead of conventional anisotropic liquid crystals. This parameter change allows the alignment to be controlled through thermal field application, simplifying the manufacturing apparatus while maintaining effective pre-tilt control for improved response characteristics.
2Manufacturing precision
If photo-alignment technique with linearly-polarized light is used, then alignment precision is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent substitutes the complex linearly-polarized light irradiation process with a simple thermal field application process. The isotropic liquid crystal composition with photo-reactive alignment groups responds to thermal fields in a manner that achieves precise alignment without requiring sophisticated optical equipment, thereby improving ease of manufacture while maintaining alignment precision.
Solution Approach 2:
The patent employs a disposable isotropic liquid crystal composition containing photo-reactive alignment groups that achieves its alignment function through simple thermal processing. This approach eliminates the need for expensive, complex light irradiation apparatus and simplifies the manufacturing process, making the overall system more economically viable despite using specialized liquid crystal materials.
3Adaptability or versatility
If liquid crystal molecules are aligned vertically without pre-tilt, then viewing angle is improved, but response characteristic to voltage is degraded due to arbitrary tilting directions
Solution Approach 1:
The patent applies preliminary action by giving a pre-tilt to the liquid crystal molecules through thermal field application during the alignment process. The isotropic liquid crystal composition with photo-reactive alignment groups is treated with a thermal field before final encapsulation, establishing a controlled initial tilt direction. This preliminary tilting prevents arbitrary direction changes during voltage application, improving response characteristics while maintaining the vertical alignment structure for wide viewing angles.
Solution Approach 2:
The patent changes the initial alignment state parameter of liquid crystal molecules by introducing a controlled pre-tilt through thermal field processing. This parameter modification ensures that when voltage is applied, molecules tilt from a known initial angle rather than from arbitrary directions, thereby improving response speed while preserving the vertical alignment configuration necessary for wide viewing angles.
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 enhances response characteristics by ensuring that liquid crystal molecules align quickly and uniformly with applied voltage, improving display quality and maintaining satisfactory characteristics over time, while simplifying the manufacturing process and eliminating the need for complex light irradiation apparatuses.
Implementation Method 1
an alignment film is formed by obliquely casting linearly-polarized ultraviolet light for irradiation to a film, which is made of a polymer including a chalcone structure and which is formed on the substrate surface, so that a double-bond portion in the chalcone structure is cross-linked
Implementation Method 2
each liquid crystal molecule has negative dielectric anisotropy, i.e., a property that the dielectric constant of the liquid crystal molecule in its major axis is smaller than that in its minor axis
Data Source
AI summary
A liquid crystal display device including an array of pixels each including first and second substrates, first and second electrodes formed on opposing surfaces of the first and second substrates, which surfaces are positioned opposite to the second and first substrates, first and second alignment restricting portions provided in the first and second electrodes, first and second alignment films covering respectively the first and second electrodes, the first and second alignment restricting portions, and the opposing surfaces of the first and second substrates, and a liquid crystal layer formed between the first and second alignment films and containing liquid crystal molecules, wherein, in each pixel, major axes of a group of liquid crystal molecules are positioned substantially in the same imaginary plane in a predetermined overlapped region between the first and second electrodes, and a pre-tilt is given to the liquid crystal molecules by at least the first alignment film.