Asymmetric Compensation Films for VA Display Viewing Angle
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Solution Overview
Problem
Vertical alignment liquid crystal displays suffer from color shifting and light leakage, which reduce the contrast ratio and viewing angle performance.
Innovation Solution
The use of compensation films with differing refractive indices on a liquid crystal display, where the upper and lower compensation films have distinct in-plane phase retardation and thickness direction phase retardation values, attached to substrates with polarizers to control light polarization and minimize color shifting and light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a vertical alignment liquid crystal display is used to achieve wide viewing angle, then the viewing angle is sufficiently wide to allow screen images to be recognized from the lateral side, but color shifting and light leakage occur which reduce the contrast ratio
Solution Approach 1:
The patent applies different compensation films with different optical characteristics (different phase retardation values and different refractive index configurations) to different regions or orientations of the display. Specifically, compensation films with different in-plane phase retardation values are used to compensate for viewing angle dependencies in different directions, thereby improving contrast ratio and reducing color shifting while maintaining wide viewing angle performance
Solution Approach 2:
The patent uses a composite structure of multiple compensation films with different optical properties. The first compensation film has different phase retardation characteristics than the second compensation film, and their combination creates a synergistic effect that simultaneously achieves wide viewing angle and high contrast ratio, resolving the contradiction between these two parameters
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 contrast ratio and reduces color shifting, improving the display's performance by ensuring better light absorption and alignment, thereby maintaining image quality across various viewing angles.
Implementation Method 1
The first and second compensation films differ in thickness and in-plane phase retardation from each other
Implementation Method 2
a first polarizer attached to an outer surface of the first compensation film, and a second polarizer attached to an outer surface of the second compensation film
Data Source
AI summary
The present invention relates to compensation films of a vertically-aligned liquid crystal display. Upper and lower compensation films asymmetrically differ in refractive index from each other.