Viewing Angle Expansion Film for LCD Tone Reversal
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Solution Overview
Problem
Liquid crystal display devices, particularly in TN and VA modes, suffer from tone reversal and reduced brightness when viewed from oblique angles, limiting their visual recognition capabilities in wide viewing angle ranges.
Innovation Solution
A viewing angle expansion film with hole-containing portions approximately parallel to each other on its surface is integrated into the liquid crystal display devices, which includes multiple resin layers with random intervals of 50 μm or less between the hole-containing portions, and is used in conjunction with a polarizing plate to expand the viewing angle range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If TN mode or VA mode liquid crystal display devices are used, then low cost and established technology are achieved, but tone reversal and reduced brightness occur when viewed from oblique directions
Solution Approach 1:
The invention divides the film structure into multiple resin layers with different properties. Specifically, it uses a first resin layer and a second resin layer with different refractive indices and molecular orientations, creating a segmented structure that compensates for viewing angle dependencies without requiring complete redesign of the entire display system.
Solution Approach 2:
The invention employs composite material structure by combining multiple resin layers with distinct optical properties. The first resin layer has one set of refractive index characteristics while the second resin layer has different characteristics, creating a composite film that achieves wide viewing angle compensation while maintaining compatibility with existing TN or VA mode liquid crystal cells.
2Adaptability or versatility
If TN mode or VA mode liquid crystal display devices are used, then established technology and low cost are achieved, but visual recognition becomes difficult in wide viewing angle range
Solution Approach 1:
The invention applies local quality by creating specific regions within the film structure that have different optical compensation functions. The first and second resin layers are positioned at different locations relative to the liquid crystal cell, with each layer having specific molecular orientations and refractive indices tailored to compensate for viewing angle issues in different directions.
3Adaptability or versatility
If phase difference layer is added to expand viewing angle, then viewing angle compensation is achieved, but device complexity increases
Solution Approach 1:
The invention achieves universality by creating a film structure that can be applied to both TN mode and VA mode liquid crystal display devices. The multi-layer resin structure with specific optical properties serves as a universal viewing angle compensation solution that works with different liquid crystal modes without requiring mode-specific design modifications.
Solution Approach 2:
The invention merges multiple functions into a single film structure. The first and second resin layers are combined in one film assembly that simultaneously provides viewing angle compensation, maintains brightness, and works with existing liquid crystal cells, eliminating the need for separate compensation 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
The integration of the viewing angle expansion film and polarizing plate enhances visual recognition by expanding the viewing angle range, reducing tone reversal, and maintaining brightness across a wider range of viewing angles.
Implementation Method 1
a plurality of hole-containing portions, which are approximately parallel to each other, on at least one surface of the viewing angle expansion film, wherein the hole-containing portion contains a hole
Implementation Method 2
containing an ultraviolet absorber
Implementation Method 3
A polarizing plate comprising: the viewing angle expansion film according to any one of (1) to (6); and a polarizer
Data Source
AI summary
The present invention provides a viewing angle expansion film which realizes visual recognition in wide viewing angle range, as well as a polarizing plate and a liquid crystal display device having the viewing angle expansion film. A viewing angle expansion film for expanding a viewing angle range including a plurality of hole-containing portions, which are approximately parallel to each other, on at least one surface of the viewing angle expansion film, wherein the hole-containing portion contains a hole, and is preferably constituted by crazes; as well as a polarizing plate and a liquid crystal display device having the viewing angle expansion film.