Humidity-Stable VA-Mode LCD Retardation Layers
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Solution Overview
Problem
Liquid-crystal display devices, particularly VA-mode devices, face challenges in maintaining high display image quality across varying humidity conditions, with contrast and color shifting significantly due to humidity changes.
Innovation Solution
A liquid-crystal display device configuration featuring two retardation layers with different humidity-dependent optical characteristics, where the slow axis of the layer with greater humidity dependence is positioned relative to the transmission axis of the polarizing element, effectively canceling out humidity-induced optical changes, and satisfying specific retardation value formulas to maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid-crystal display devices are used, then the device structure is simple, but the contrast and color change significantly depending on humidity
Solution Approach 1:
The patent divides the retardation function into two separate layers: a first retardation layer with high humidity dependence and a second retardation layer with low humidity dependence. This segmentation allows each layer to perform a specific function - the first layer provides the necessary retardation while the second layer compensates for humidity-induced changes, thereby maintaining display quality without requiring complex single-layer solutions
Solution Approach 2:
The patent changes the optical parameters of the retardation layers by selecting materials with different humidity dependence characteristics. The first retardation layer uses a polymer with high humidity dependence (ΔRe > 50 nm), while the second layer uses a polymer with low humidity dependence (ΔRe ≤ 50 nm). This parameter differentiation enables the system to maintain stable optical performance across varying humidity conditions
2Illumination intensity
If VA-mode liquid-crystal display devices are used, then high contrast is achieved, but color and contrast change largely among different viewing angles and humidity conditions
Solution Approach 1:
The second retardation layer acts as an intermediary element that mediates between the first retardation layer and the viewing environment. It compensates for the humidity-induced optical changes in the first layer, thereby maintaining the high contrast ratio characteristic of VA-mode displays while adding adaptability to humidity and viewing angle variations
Solution Approach 2:
The patent employs a composite structure combining two different polymer materials with distinct humidity dependence properties. This composite approach allows the display device to leverage the high contrast advantage of VA-mode while compensating for its sensitivity to viewing angle and humidity through the combined optical effects of the two materials
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 solution significantly reduces humidity-dependent fluctuations in optical characteristics, thereby minimizing contrast and color shifts across different humidity conditions, enhancing the display's viewing angle stability and overall image quality.
Implementation Method 1
a first retardation layer between the first polarizing element and the liquid-crystal cell, and a second retardation layer between the second polarizing element and the liquid-crystal cell
Data Source
AI summary
A liquid-crystal display device comprising a liquid-crystal cell, a first polarizing element and a second polarizing element disposed on either side of the liquid-crystal cell respectively, a first retardation layer between the first polarizing element and the liquid-crystal cell, and a second retardation layer between the second polarizing element and the liquid-crystal cell, wherein a transmission axis of the first polarizing element is perpendicular to the slow axis of the first retardation layer; and a transmission axis of the second polarizing element is parallel to the slow axis of the second retardation layer; and the first retardation layer and the second retardation layer satisfy the formula (1) 0 nm<ΔRe1(548)−ΔRe2(548)≦50 nm.