Liquid Crystal Display Panel Optical Compensation Layers
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Solution Overview
Problem
Liquid crystal display panels face issues with light leakage and color cast at side viewing angles due to phase retardation and birefringence effects, leading to suboptimal display performance.
Innovation Solution
Incorporating a first optical compensation layer with in-plane retardation between 90 nm to 230 nm and a second optical compensation layer with thickness direction retardation between -30 nm to -180 nm, along with a third optical compensation layer to offset phase retardations, ensuring polarized light is linearly polarized perpendicular to the second polarizer's transmission axis, reducing light leakage and color deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid crystal display panel structure is used, then the display panel can be manufactured with standard components, but light leakage and color cast occur at side viewing angles due to phase retardation and birefringence effects
Solution Approach 1:
The patent introduces optical compensation layers as intermediary elements between the liquid crystal layer and the polarizers. These compensation layers (including the first optical compensation layer with in-plane retardation and the second optical compensation layer with thickness direction retardation) act as mediators that offset the phase retardation and birefringence effects caused by the liquid crystal layer, thereby eliminating light leakage and color cast at side viewing angles without changing the fundamental LCD structure
Solution Approach 2:
The patent applies parameter changes by selecting specific retardation values for the optical compensation layers. The first optical compensation layer has in-plane retardation Ro1 in the range of 90 nm to 230 nm, and the second optical compensation layer has thickness direction retardation Rth2 in the range of -30 nm to -180 nm. By carefully controlling these optical parameters, the compensation layers can precisely counterbalance the phase retardation effects of the liquid crystal layer across different viewing angles
2Reliability
If optical compensation layers are added to reduce light leakage, then display quality improves, but device complexity increases
Solution Approach 1:
The patent divides the optical compensation function into multiple separate layers with distinct functions. The first optical compensation layer addresses in-plane phase retardation with retardation Ro1 of 90 nm to 230 nm, while the second optical compensation layer addresses thickness direction retardation with Rth2 of -30 nm to -180 nm. This segmentation allows each layer to be optimized for its specific function and simplifies the overall design by breaking down the complex compensation requirement into manageable components
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
Significantly reduces light leakage and color cast at side viewing angles, improving display quality by ensuring most light does not exit through the second polarizer and minimizing color deviations across different viewing angles.
Implementation Method 1
a first optical compensation layer disposed between the liquid crystal layer and any of the first polarizer and the second polarizer, an orthographic projection of an optical axis of the first optical compensation layer on the first polarizer being perpendicular to the orthographic projections of the optical axes of the first liquid crystal molecules on the first polarizer
Implementation Method 2
a second optical compensation layer disposed on a same side of the liquid crystal layer as the first optical compensation layer, an optical axis of the second optical compensation layer being perpendicular to a plane where the second optical compensation layer is located
Data Source
AI summary
A liquid crystal display panel includes a first polarizer, a second polarizer, a liquid crystal layer including first liquid crystal molecules, a first optical compensation layer between the liquid crystal layer and any of the first polarizer and the second polarizer, a second optical compensation layer on a same side of the liquid crystal layer as the first optical compensation layer. In a non-powered state of the liquid crystal display panel orthographic projections of optical axes of the first liquid crystal molecules on the first polarizer, which are perpendicular to an orthographic projection of an optical axis of the first optical compensation layer on the first polarizer, are parallel to any of transmission axes of the first polarizer and the second polarizer that are perpendicular to each other. An optical axis of the second optical compensation layer is perpendicular to a plane where the second optical compensation layer is located.