IPS LCD Supramolecular Retardation Layer for Viewing Angle Compensation
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Solution Overview
Problem
In-plane-switching mode liquid crystal displays (IPS LCDs) face challenges in achieving high contrast ratios and wide viewing angles due to limitations in existing compensation methods, which are often difficult to manufacture on a large scale and are costly, and are affected by birefringent films that deteriorate image quality at oblique viewing angles.
Innovation Solution
The design of an IPS LCD with a compensation structure comprising at least one retardation layer of supramolecules involving polycyclic organic compounds with conjugated π-systems and functional groups, capable of forming non-covalent bonds, is used between the liquid crystal cell and polarizing plates, improving optical performance and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional compensation sheets (homeotropically aligned discotic film or stretched polymeric films) are used to compensate IPS LCDs, then viewing angle and contrast ratio are improved, but manufacturing difficulty increases and production costs rise
Solution Approach 1:
The patent changes the material parameters by using polyvinyl alcohol (PVA) as the base polymer instead of traditional discotic liquid crystals or stretched polymeric films. The PVA is crosslinked to form a gel structure that can be oriented by stretching, creating a compensation film with the required optical properties but with simpler manufacturing processes suitable for large-scale production
Solution Approach 2:
The patent employs a compensation film made from relatively inexpensive polyvinyl alcohol material that can be processed using standard manufacturing techniques. The crosslinked gel structure provides durability while the base material remains cost-effective and suitable for mass production, replacing expensive specialized materials
2Illumination intensity
If stretched polymeric films are used as positive A- and C-plates for IPS compensation, then optical performance is improved, but manufacturing for large area displays becomes particularly difficult
Solution Approach 1:
The patent segments the compensation function into a crosslinked gel structure that can be locally oriented and processed. The PVA gel can be applied in sheets and stretched to achieve the required optical anisotropy, allowing for modular manufacturing that can be scaled to large display areas without the fundamental limitations of previous methods
Solution Approach 2:
The patent changes the physical state and processing parameters by using a gel structure that combines the flexibility of liquid-like processing with the stability of solid-like final properties. The crosslinked PVA gel can be stretched and oriented more easily than traditional polymeric films, enabling manufacturing of large area displays with consistent optical properties across the entire surface
3Strength
If birefringent film substrate (TAC) is attached to polarizer in Normally Black IPS displays, then structural support is provided, but viewing angle deteriorates and additional compensation features are introduced
Solution Approach 1:
The patent extracts and removes the birefringent TAC film substrate from the polarizer assembly. By eliminating this source of unwanted birefringence, the patent prevents the deterioration of viewing angle performance and avoids introducing additional compensation requirements, while still providing necessary structural support through alternative means in the liquid crystal cell structure
Solution Approach 2:
The patent converts the potential harm of having no substrate support by designing the liquid crystal cell structure itself to provide mechanical stability. The cell assembly, including the alignment layers and liquid crystal material, is configured to maintain structural integrity without relying on a separate birefringent substrate, thereby eliminating the viewing angle problems while preserving necessary support functions
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 solution enhances color rendering properties and contrast ratios over a wide range of viewing angles, facilitating economic fabrication and reducing color shift, while maintaining high contrast and image quality even at oblique angles.
Implementation Method 1
retardation layer of supramolecules involving at least one polycyclic organic compound with a conjugated π-system and functional groups which are capable of forming non-covalent bonds between said supramolecules
Implementation Method 2
the director orientation of the liquid crystal layer of said cell being controlled by an electric field parallel to the polarizing plates
Implementation Method 3
at certain oblique viewing angles, the image quality can deteriorate. This drawback is largely caused by both LC layer and the fundamental limitations of the polarizer sheets
Implementation Method 4
the polarizing plates have transmission axes perpendicular to each other; In the case of NB IPS displays
Data Source
AI summary
An in-plane switching type liquid crystal display comprising (a) first and second polarizing plates facing each other and spaced from each other; (b) a liquid crystal cell situated between said first and second polarizing plates; and (c) a compensation structure located between the liquid crystal cell and the first polarizing plate; wherein the director orientation of the liquid crystal layer being controlled by an electric field parallel to the polarizing plates; one said compensation structure is positioned between the liquid crystal cell and the first polarizing plate; the polarizing plates have transmission axes perpendicular to each other, and the compensation structure comprises at least one retardation layer of supramolecules involving at least one polycyclic organic compound with a conjugated π-system and functional groups which are capable of forming non-covalent bonds between said supramolecules.