Liquid Crystal Panel In-Cell Retardation Layer Curing
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Solution Overview
Problem
Conventional liquid crystal display devices suffer from reduced contrast ratio and display quality when used outdoors due to external light reflection, and the development of an in-cell retardation layer to address this has resulted in long-term reliability issues, such as whitening at the outer peripheral portions during black display under high-temperature and high-humidity conditions.
Innovation Solution
A method for producing a liquid crystal panel that includes a first and second reactive mesogen layer with different material wavelength dispersibilities, arranged orthogonally, and an out-cell retardation layer, which are optimized to maintain retardation values and wavelength dispersibility even under high-temperature and high-humidity conditions, using specific ultraviolet light illuminance levels during curing to enhance long-term reliability and low reflection characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a retardation film is attached to the liquid crystal panel to reduce external light reflection and improve outdoor visibility, then low reflection characteristics are improved, but device complexity and thickness increase
Solution Approach 1:
The patent combines the retardation function with the liquid crystal layer by forming an in-cell retardation layer directly within the liquid crystal panel structure. This merging eliminates the need for a separate out-cell retardation film, thereby reducing device complexity and thickness while maintaining the low reflection characteristics needed for outdoor visibility.
Solution Approach 2:
The in-cell retardation layer is nested within the liquid crystal panel structure, specifically positioned between the liquid crystal layer and the color filter layer. This nesting approach integrates the retardation function inside the existing panel architecture, avoiding additional external components and reducing overall device thickness.
2Device complexity
If an in-cell retardation layer is provided in the liquid crystal panel to reduce thickness and number of members, then device complexity is reduced, but long-term reliability deteriorates due to whitening defects under high-temperature and high-humidity conditions
Solution Approach 1:
The patent segments the in-cell retardation layer into multiple distinct layers: a first reactive mesogen layer and a second reactive mesogen layer, each with different material wavelength dispersibilities. This segmentation allows each layer to contribute differently to the overall retardation effect, improving long-term reliability under high-temperature and high-humidity conditions while preventing whitening defects.
Solution Approach 2:
The patent employs composite materials by combining reactive mesogen layers with different material wavelength dispersibilities (one with positive dispersibility and one with negative dispersibility). This composite structure maintains stable retardation values and prevents whitening defects under extreme environmental conditions, thereby improving long-term reliability.
3Ease of manufacture
If a single reactive mesogen layer is used in the in-cell retardation layer, then manufacturing process is simplified, but wavelength dispersibility and retardation stability under high-temperature and high-humidity conditions deteriorate
Solution Approach 1:
The patent introduces dynamic control of wavelength dispersibility by using reactive mesogen layers with opposite dispersibility characteristics (positive and negative). This dynamic composition allows the system to maintain stable retardation values across different wavelengths and environmental conditions, preventing whitening defects while managing manufacturing complexity.
4Productivity
If the ultraviolet light illuminance during curing is increased to improve curing efficiency, then productivity is improved, but manufacturing precision deteriorates due to potential damage to the liquid crystal molecules
Solution Approach 1:
The patent applies periodic action by using intermittent or staged ultraviolet light irradiation during the curing process. This approach allows sufficient curing efficiency while preventing excessive heat buildup and potential damage to liquid crystal molecules, thereby maintaining manufacturing precision.
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 effectively improves the long-term reliability and outdoor visibility of liquid crystal panels by maintaining retardation values and wavelength dispersibility, preventing display defects like whitening during black display, even under extreme conditions.
Implementation Method 1
curing a first reactive mesogen layer with ultraviolet light
Data Source
AI summary
The present invention relates to a method for producing a liquid crystal panel. The method includes curing a first reactive mesogen layer with ultraviolet light at an illuminance within a range of 40 to 90 mW/cm2. The liquid crystal panel includes a first transparent base material, a TFT layer and a first alignment film stacked in order on the first transparent base material, a second transparent base material, a color filter layer, an in-cell retardation layer, and a second alignment film stacked in order on the second transparent base material, a liquid crystal layer sandwiched between the first alignment film and the second alignment film, an out-cell retardation layer disposed on a side opposite to a color filter layer side of the second transparent base material, and a pair of linearly polarizing plates arranged so as to sandwich the first transparent base material and the out-cell retardation layer and having transmission axes orthogonal to each other. The in-cell retardation layer includes the first reactive mesogen layer and a second reactive mesogen layer. The first reactive mesogen layer and the second reactive mesogen layer have different material wavelength dispersibilities and have slow axes arranged orthogonal to each other.