Retardation Layer Optical Compensation for LCD Viewing Angles
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Solution Overview
Problem
Liquid crystal display devices used by multiple viewers from various angles suffer from inadequate viewing angle characteristics due to fluctuations in optical properties and susceptibility to scratches in existing optical compensation methods.
Innovation Solution
A liquid crystal display device configuration incorporating a pair of polarizing layers with orthogonal absorption axes, a liquid crystal cell with a retardation layer having specific optical characteristics, and a retardation layer disposed between the polarizing layers or the liquid crystal cell, utilizing materials like cyclic olefin copolymers, cellulose acylates, or polycarbonates, and produced through a process involving different roll speeds to achieve improved optical compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optically compensatory film having an optically anisotropic layer composed of a liquid crystal composition is used for optical compensation, then the viewing angle characteristics can be improved, but the optical properties fluctuate and the film surfaces are readily scratched
Solution Approach 1:
The patent changes the material composition parameter by replacing liquid crystal composition with polymer composition, and changes the optical axis orientation parameter by creating a tilted optical axis structure. This resolves the contradiction by maintaining viewing angle improvement while eliminating the instability and scratching issues of liquid crystal films.
Solution Approach 2:
The patent uses composite material structure by combining polymer materials with specific optical properties to create the compensatory film. The composite structure of the polymer matrix with controlled optical anisotropy provides both the needed optical compensation and the mechanical stability to prevent scratching and property fluctuation.
2Manufacturing precision
If a polymer film whose optical axis is inclined in the thickness direction is used for optical compensation, then the optical property stability improves, but the viewing angle characteristics remain inadequate when observed by multiple persons from various directions
Solution Approach 1:
The patent optimizes the tilt angle parameter of the optical axis within a specific range (5-45 degrees from the normal direction) and adjusts the retardation parameter to achieve both stable optical properties and improved viewing angle characteristics for multi-viewer conditions.
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 enhances viewing angle characteristics by reducing contrast dependency and grayscale inversion, providing a stable and uniform display across different viewing angles without surface scratches, using a retardation layer with tailored optical properties and materials.
Implementation Method 1
a retardation layer disposed between at least one of the pair of polarizing layers and the liquid crystal cell
Implementation Method 2
a pair of polarizing layers disposed so that respective absorption axes thereof are orthogonal to each other
Data Source
AI summary
The invention relates to a liquid crystal display device comprising a retardation layer wherein an in-plane slow axis of the retardation layer is within the direction of 90±40 degrees relative to an absorption axis of the polarizing layer disposed at a closer position to the retardation layer; Re(550) meets following relation, 25 nm≦̸Re(550)≦̸230 nm; R[40°] of the retardation layer which is measured for incident light in a direction tilted by 40 degrees toward the tilt direction of the retardation layer relative to the normal line of the retardation layer meets following relation, 0 nm≦̸R[40°]≦̸300 nm; and R[+40°] of the retardation layer and retardation R[−40°] of the retardation layer meet following relation, 1<R[+40°]/R[−40°].