Iodine-Dyed Polarizing Plate Two-Stage Drying Process
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Solution Overview
Problem
Liquid crystal displays (LCDs) face challenges in achieving high brightness while minimizing power consumption due to high power consumption from light sources, which is exacerbated by the need for multiple light sources to compensate for low transmittance in conventional polarizing plates.
Innovation Solution
A method for manufacturing a polarizing plate with high transmittance and contrast ratio by dyeing a base film with iodine, stretching it, and drying it at controlled temperatures, resulting in a polarizing plate with single transmittance of 42.7% to 43.8% and a contrast ratio of 950 or more, which can be used in LCDs to reduce the number of light sources required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional polarizing plates are used, then the LCD structure is simple, but the transmittance is low requiring multiple light sources
Solution Approach 1:
The patent applies parameter changes by optimizing the drying temperature profile of the polarizing film. Specifically, it uses a two-stage drying process: first at a temperature below the glass transition temperature (45-55°C) to remove moisture without causing film deformation, then at a temperature above the glass transition temperature (70-80°C) to achieve complete drying and maximize transmittance. This temperature parameter optimization enables the polarizing plate to achieve high transmittance (42.7%-43.8%) while maintaining single light source operation.
2Manufacturing precision
If the base film is dried at high temperature, then the drying is complete, but the polarizing film deforms
Solution Approach 1:
The patent segments the drying process into two distinct stages based on temperature thresholds. The first stage uses temperature below the glass transition temperature to remove bulk moisture safely. The second stage uses temperature above the glass transition temperature to complete drying. This segmentation allows the process to achieve complete drying without causing film deformation, as each stage operates within safe temperature parameters for the respective phase.
Solution Approach 2:
The patent changes the temperature parameter dynamically during the drying process. By monitoring and adjusting temperature based on the glass transition temperature of the polarizing film, the process achieves complete moisture removal while maintaining film integrity. The temperature is increased from below-glass-transition levels to above-glass-transition levels in a controlled manner to balance drying efficiency with film stability.
3Illumination intensity
If more light sources are used, then the brightness is sufficient, but the power consumption increases
Solution Approach 1:
The patent changes the optical parameters of the polarizing plate by optimizing the drying temperature profile. This results in enhanced transmittance (42.7%-43.8%) that allows the system to achieve sufficient brightness with fewer or no additional light sources, thereby reducing power consumption while maintaining display quality.
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 polarizing plate enhances the brightness of LCDs by approximately 5% compared to conventional plates, allowing for lower power consumption while maintaining high contrast ratios, even with fewer light sources.
Implementation Method 1
The base film is dyed by using iodine. When the base film is dyed by using iodine, the base film is immersed into an iodine aqueous solution having a specific gravity of about 1.4 to about 1.7.
Implementation Method 2
the polarizing film is dried at a first temperature. Thereafter, the polarizing film is dried while sequentially increasing a temperature from the first temperature to a second temperature higher than the first temperature.
Data Source
AI summary
A method of manufacturing a polarizing plate includes fabricating a base film, dyeing the base film by using iodine, stretching the base film to form a polarizing film, firstly drying the polarizing film at a first temperature, and secondly drying the polarizing film while sequentially increasing a temperature from the first temperature to a second temperature higher than the first temperature. The polarizing plate and a liquid crystal display including the same are manufactured through the above method.