Liquid Crystal Display Polarizing Plates with Asymmetric Moisture Permeability
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Solution Overview
Problem
Liquid crystal display devices suffer from light leaks due to temperature and moisture changes, leading to reduced performance and increased production costs, particularly with conventional polarizing plates that require low moisture permeability protective films.
Innovation Solution
A liquid crystal display device configuration with a first polarizing plate on the backlight side using a protective film with high moisture permeability and a second polarizing plate on the viewing side with low moisture permeability, optimizing the moisture permeability of protective films to minimize light leaks and reduce production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective film with low moisture permeability is used for the polarizing plate on the viewing side, then the durability under high-moisture conditions is improved and light leaks are prevented, but the production cost increases and productivity decreases
Solution Approach 1:
The invention applies different moisture permeability characteristics to different locations: the viewing side polarizing plate uses low moisture permeability film for protection, while the backlight side polarizing plate uses high moisture permeability film for cost-effectiveness and productivity. This local differentiation resolves the contradiction by applying the protective quality only where necessary (viewing side exposed to environment) while using economical materials where exposed to controlled conditions (backlight side).
2Reliability
If protective films with low moisture permeability are used on both polarizing plates, then light leaks are prevented, but the production cost increases
Solution Approach 1:
The invention differentiates the protective film requirements by location: viewing side polarizing plate uses low moisture permeability film to prevent light leaks, while backlight side polarizing plate uses high moisture permeability film that is more cost-effective and easier to manufacture. This local quality approach prevents light leaks where needed while reducing overall production cost.
3Reliability
If a protective film with low moisture permeability is used, then the durability of the polarizing plate is improved, but the process of pasting and drying requires more time
Solution Approach 1:
The invention applies low moisture permeability protective films only to the viewing side polarizing plate where durability is critical, while using high moisture permeability films on the backlight side where the pasting and drying time is less critical. This local differentiation reduces overall processing time while maintaining necessary durability.
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
This configuration enhances the durability of polarizing plates under high-moisture conditions, reducing light leaks and improving display quality while maintaining cost-effectiveness.
Implementation Method 1
a moisture permeability of the protective films on both sides of the first polarizing plate at a temperature of 60° C. and a relative humidity of 95% is more than 300 g/m2·day
Data Source
AI summary
The present invention provides a liquid crystal display device containing: a liquid crystal cell; a backlight; a first polarizing plate disposed between the liquid crystal cell and the backlight and having a polarizer and at least two protective films disposed so as to sandwich the polarizer; and a second polarizing plate disposed on a side of the liquid crystal cell opposite to a side on which the first polarizing plate is provided and having a polarizer and at least two protective films disposed so as to sandwich the polarizer, wherein a moisture permeability of the protective films on both sides of the first polarizing plate at 60° C. and 95% RH is more than 300 g/m2·day, and a moisture permeability of at least one protective film of the second polarizing plate at 60° C. and 95% RH is equal to or less than 300 g/m2·day.