Liquid Crystal Display Four Polarizers Contrast Luminance
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Solution Overview
Problem
The use of multiple liquid crystal display panels to improve contrast ratio in liquid crystal display devices leads to a decrease in luminance due to reduced transmittance, as light is transmitted through multiple layers of polarizing plates, compromising image quality.
Innovation Solution
The implementation of a liquid crystal display device configuration with specific arrangements and polarizing plate relationships, where the degrees of polarization of polarizing plates are optimized to maintain high contrast ratios while increasing transmittance, including the use of reflection type polarizing plates and in-cell reflection type polarizing plates to enhance light transmission and reduce heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple liquid crystal display panels are superimposed to improve contrast ratio, then the contrast ratio is improved, but the transmittance decreases causing luminance degradation
Solution Approach 1:
The patent applies parameter changes by setting specific degree of polarization values for each of the four polarizing plates (P1, P2, P3, P4) where at least one plate has a degree of polarization of 99.5% or higher, while others have lower values. This differential parameter assignment optimizes the balance between contrast ratio and transmittance, resolving the contradiction by allowing high contrast through selective high polarization plates while maintaining overall light transmission through the multi-plate structure.
Solution Approach 2:
The patent uses a composite structure of four polarizing plates with different degree of polarization characteristics combined with two liquid crystal cells. This composite arrangement allows the system to achieve both high contrast ratio (through the polarizing effect of multiple plates) and adequate transmittance (through the selective use of high and low polarization plates), effectively resolving the luminance-contradiction trade-off.
2Measurement precision
If multiple polarizing plates are used to achieve high contrast ratio, then the contrast ratio is improved, but heat generation increases due to light absorption
Solution Approach 1:
The patent addresses heat generation by varying the degree of polarization parameter across different plates. Plates with lower degree of polarization allow more light transmission and generate less heat, while plates with higher degree of polarization (99.5% or higher) are strategically positioned to provide contrast enhancement where needed. This parameter differentiation reduces overall heat accumulation while maintaining high contrast ratio.
3Measurement precision
If the degree of polarization of all polarizing plates is increased to improve contrast ratio, then the contrast ratio is improved, but the transmittance decreases further
Solution Approach 1:
The patent applies local quality by assigning different degree of polarization values to different polarizing plates based on their positional and functional requirements. At least one plate has a degree of polarization of 99.5% or higher to provide strong polarization effect for contrast, while other plates have lower values to minimize light absorption and maintain transmittance. This localized optimization of polarization strength resolves the contradiction between contrast enhancement and light transmission preservation.
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 effectively prevents the decrease in luminance while maintaining high contrast ratios, improving image quality and reliability by optimizing the degrees of polarization and transmittance of polarizing plates, and reducing heat issues associated with light absorption.
Implementation Method 1
a first polarizing plate disposed on a front side of the first liquid crystal cell; a second polarizing plate disposed between the first liquid crystal cell and the second liquid crystal cell; a third polarizing plate disposed between the second polarizing plate and the second liquid crystal cell; and a fourth polarizing plate disposed on a back side of the second liquid crystal cell
Data Source
AI summary
A liquid crystal display device includes: a first polarizing plate, a first liquid crystal cell, a second polarizing plate, a third polarizing plate, a second liquid crystal cell, and a fourth polarizing plate, which are arranged from a front side to a back side in this order. P1, P2, P3, P4 represent degrees of polarization of the first polarizing plate, the second polarizing plate, the third polarizing plate, and the fourth polarizing plate, respectively, one of a relational expression of P1>P2, P3, P4, a relational expressions of P4>P1, P2, P3, and a relational expression of P1, P4>P2, P3 is satisfied.