Optical Laminate Retardation Layer for IPS Diagonal Contrast
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Solution Overview
Problem
In-plane switching (IPS) mode liquid crystal displays face challenges with low contrast ratio at diagonal direction angles and significant visibility differences between right and left sides, and existing solutions like positive C layers increase thickness and cost while providing limited improvements.
Innovation Solution
An optical laminate comprising a polarizer with a stacked retardation layer, specifically a positive C layer with controlled in-plane and out-of-plane retardations, and a tilted slow axis angle, enhances contrast ratio and reduces visibility differences without additional layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a positive C layer is added to improve contrast ratio at diagonal angles, then contrast ratio is improved, but thickness of the polarizing plate increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the in-plane retardation (0-30 nm) and out-of-plane retardation (-50 nm to -15 nm) of the positive C layer, along with the tilted angle relationship between the slow axis and light absorption axis. This optimized parameter combination achieves improved contrast ratio at diagonal angles while maintaining the polarizing plate within acceptable thickness limits, resolving the contradiction between performance improvement and thickness increase.
2Illumination intensity
If a positive C layer with liquid crystals is used to improve visibility, then visibility difference is reduced, but cost increases and durability decreases
Solution Approach 1:
The patent replaces expensive and less durable liquid crystal materials in the positive C layer with more durable and cost-effective alternative materials that can achieve the required optical performance. This substitution maintains the visibility improvement function while significantly reducing material cost and enhancing long-term durability, directly addressing the reliability concerns.
3Illumination intensity
If additional retardation layers are stacked to improve contrast ratio, then contrast ratio is improved, but device complexity increases
Solution Approach 1:
The patent makes the positive C layer multi-functional by optimizing it to simultaneously achieve contrast ratio improvement at diagonal angles, reduce visibility differences between right and left sides, and suppress light leakage. This consolidation of multiple optical functions into a single layer eliminates the need for stacking additional retardation layers, thereby reducing device complexity while maintaining comprehensive optical performance.
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 optical laminate significantly improves contrast ratio at diagonal angles and minimizes visibility differences between right and left sides, while maintaining a compact design and reducing light leakage.
Implementation Method 1
the positive C layer having an in-plane retardation of 0 nm to 30 nm and an out-of-plane retardation of −50 nm to −15 nm at a wavelength of 550 nm
Data Source
AI summary
Disclosed are an optical laminate and an optical display apparatus including the same. The optical laminate includes: a polarizer; and a retardation layer stacked on a light incidence surface of the polarizer, wherein the retardation layer includes a positive C layer, the positive C layer having an in-plane retardation of 0 nm to 30 nm and an out-of-plane retardation of −50 nm to −15 nm at a wavelength of 550 nm, and the in-plane retardation of the positive C layer at a wavelength of 550 nm and an absolute value of a tilted angle of a slow axis of the positive C layer with respect to a light absorption axis of the polarizer satisfy Relation 1.