Liquid Crystal Panel with Three Polarizing Plates and Retardation Layers
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Solution Overview
Problem
Liquid crystal display apparatuses face challenges in achieving high contrast ratios due to insufficient polarization of polarizing plates, which affects the clarity and brightness of displayed characters and images, especially in front and oblique directions.
Innovation Solution
A liquid crystal panel configuration is introduced, featuring three polarizing plates with adjusted light transmittance and two retardation plates placed between the liquid crystal cell and the polarizing plates, where the refractive index ellipsoids of the retardation plates have a specific relationship (nx>ny>nz), and the transmittance of the second polarizing plate is higher than the first, with the third polarizing plate's transmittance equal to or greater than the first, enhancing polarization and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polarizing plates are used in the liquid crystal display apparatus, then the device structure is simple, but the contrast ratio is low due to insufficient polarization
Solution Approach 1:
The single polarizing plate is segmented into three separate polarizing plates (first, second, and third polarizing plates) with different light transmittance characteristics. This segmentation allows each plate to perform specific functions: the first and third plates provide basic polarization, while the second plate with higher transmittance enhances the polarization effect, thereby improving the contrast ratio without requiring a single complex polarizing element
Solution Approach 2:
Different regions of the optical path are assigned different polarizing properties through the three polarizing plates positioned at specific locations relative to the liquid crystal cell. The plates have varying light transmittance (T1, T2, T3) optimized for their respective positions, creating local quality variations that collectively enhance the overall polarization effect and contrast ratio
2Illumination intensity
If the light transmittance of all polarizing plates is increased to improve brightness, then the brightness of white images improves, but the brightness of black images also increases, reducing the contrast ratio
Solution Approach 1:
The light transmittance parameter is varied across the three polarizing plates instead of using uniform transmittance. The second polarizing plate has a higher light transmittance (T2) than the first (T1) and third (T3) plates, creating a parameter gradient that optimizes both brightness and contrast. This parameter change allows the system to achieve high brightness while maintaining dark black levels through the combined effect of the three plates
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 significantly improves the contrast ratio in the front direction and overall display properties by optimizing light transmittance and polarization, resulting in a higher brightness for white images and reduced brightness for black images, enhancing the display quality of liquid crystal display apparatuses.
Implementation Method 1
a first retardation plate placed between the liquid crystal cell and the first polarizing plate; and a second retardation plate placed between the liquid crystal cell and the second polarizing plate
Implementation Method 2
a first polarizing plate placed on one side of the liquid crystal cell; a second polarizing plate and a third polarizing plate placed on another side of the liquid crystal cell
Data Source
AI summary
A liquid crystal panel of the present invention includes: a liquid crystal cell; a first polarizing plate placed on one side of the liquid crystal cell; a second polarizing plate and a third polarizing plate placed on another side of the liquid crystal cell in the stated order from a side of the liquid crystal cell; a first retardation plate placed between the liquid crystal cell and the first polarizing plate; and a second retardation plate placed between the liquid crystal cell and the second polarizing plate, in which: refractive index ellipsoids of the first retardation plate and the second retardation plate exhibit a relationship of nx>ny>nz; and a transmittance (T2) of the second polarizing plate is larger than a transmittance (T1) of the first polarizing plate, and a transmittance (T3) of the third polarizing plate is equal to or larger than the transmittance (T1) of the first polarizing plate.