Liquid Crystal Display Viewing Angle Compensation
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Solution Overview
Problem
Liquid crystal display devices employing in-plane switching (IPS) or fringe field switching (FFS) types with optical alignment processes exhibit worse viewing angle characteristics due to greater retardation in self-assembled optical alignment films compared to those using rubbing alignment processes, leading to compromised contrast and display quality.
Innovation Solution
The liquid crystal display device incorporates self-assembled optical alignment films with in-plane retardation greater than or equal to 1 nm, where the relationship between the thickness-direction retardation and in-plane retardation of protective layers is optimized to improve viewing angle characteristics, and the transmission axis of the polarizer is strategically aligned relative to the initial alignment direction of liquid crystal molecules to compensate for the retardation effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If optical alignment process is employed to achieve high contrast, then contrast is improved, but viewing angle characteristics worsen
Solution Approach 1:
The patent changes the optical parameters of the alignment film by controlling its in-plane retardation to be 1 nm or more, which compensates for the retardation effect and improves viewing angle characteristics while maintaining high contrast through optimized relationship between thickness-direction retardation and in-plane retardation
2Manufacturing precision
If self-assembled optical alignment film is used, then alignment precision is improved, but retardation increases causing worse viewing angle characteristics
Solution Approach 1:
The patent optimizes the retardation parameters of the alignment film by setting in-plane retardation to 1 nm or more and establishing a specific relationship between thickness-direction retardation and in-plane retardation, thereby compensating for excessive retardation effects and improving viewing angle characteristics
3Illumination intensity
If optical alignment film with greater retardation is used, then contrast is improved, but viewing angle characteristics deteriorate
Solution Approach 1:
The patent changes the retardation parameters by setting in-plane retardation to 1 nm or more and establishing an optimized relationship between thickness-direction retardation and in-plane retardation, which compensates for the harmful retardation effect and improves viewing angle characteristics while maintaining contrast
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 viewing angle characteristics of the liquid crystal display device, providing improved contrast and display quality by effectively compensating for the retardation in the optical alignment films.
Implementation Method 1
an optical alignment process, not an alignment process by rubbing in the related art, in which the alignment direction is defined by irradiating an alignment film with light
Implementation Method 2
the cause of worsening of the viewing angle characteristics is the existence of a greater retardation in a self-assembled optical alignment film
Data Source
AI summary
The present invention is a liquid crystal display device including a first polarizer, a first protective layer, a first substrate, a first optical alignment film, a liquid crystal layer, a second optical alignment film, a second substrate including a signal electrode and an opposite electrode, a second protective layer, a second polarizer in this order, in which the layers satisfy the relationship nx=ny≥nz, an in-plane retardation of each of optical alignment films is greater than or equal to 1 nm, given that R1 is a thickness-direction retardation of each of the protective layers and that R2 is the in-plane retardation of each of optical alignment films, the relationship R1≤0.047R22−2.1R2+44.3 is satisfied, the liquid crystal layer has a positive dielectric anisotropy, and a transmission axis of the second polarizer is perpendicular to an initial alignment direction of the liquid crystal molecules.