Dichroic Guest-Host Polarizer Using Polymerized Liquid Crystal Host
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Solution Overview
Problem
Conventional dichroic guest-host polarizers used in liquid crystal displays (LCDs) are too thick for applications inside liquid crystal cells and do not meet the optical performance requirements for demanding LCD applications like LCD TVs, as they have a low dichroic ratio and are sensitive to moisture and mechanical damage.
Innovation Solution
A very thin dichroic guest-host polarizer is developed using an oriented polymer film with a polymerized liquid crystal host and a dichroic light-absorbing guest, achieving a high dichroic ratio of 15 or more, which allows for thin-film formation and integration inside liquid crystal cells without the need for protective layers or adhesives, utilizing smectic phases and specific polymerizable liquid crystals for enhanced orientation and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a conventional H-sheet polarizer is used, then linear polarization is achieved with good optical performance, but the thickness is too large (70-150 μm) for inside-cell applications
Solution Approach 1:
The patent changes the fundamental parameters of the polarizer system by using polymerizable liquid crystal hosts in smectic phases with high order parameters (S≥0.8), which enables achieving high dichroic ratios (≥15) in extremely thin films (≤10 μm, preferably ≤5 μm). This parameter change in the host material properties allows thin-film formation while maintaining or improving optical performance.
Solution Approach 2:
The patent employs composite materials consisting of polymerizable liquid crystal hosts combined with dichroic guests. The host-guest composite system leverages the high orientational order of smectic phase liquid crystals to achieve superior dichroic ratios in thin films, overcoming the limitations of conventional H-sheet polarizers.
2Length of moving object
If the polarizer thickness is reduced to enable inside-cell application, then the dichroic ratio and optical performance deteriorate
Solution Approach 1:
The patent achieves high dichroic ratios in thin films by changing the order parameter of the liquid crystal host to S≥0.8 in smectic phases, which provides sufficient molecular alignment even at thicknesses ≤10 μm. This parameter change ensures that the dichroic ratio remains ≥15 despite the reduced thickness.
Solution Approach 2:
The patent utilizes phase transitions of polymerizable liquid crystals into smectic phases (SA, SC, SB, or smectic X phases) to achieve high orientational order. The phase transition enables the system to maintain high dichroic ratios in thin films by exploiting the inherent high order parameter of the smectic phase structure.
3Reliability
If conventional poly(vinylalcohol) films are used, then linear polarization is achieved, but the films are sensitive to moisture ingress and polymer relaxation
Solution Approach 1:
The patent replaces conventional poly(vinylalcohol) with polymerizable liquid crystal hosts that form composite systems with dichroic guests. This composite material system eliminates moisture sensitivity while maintaining optical performance stability, as the liquid crystal polymer network is inherently resistant to moisture ingress and polymer relaxation.
Solution Approach 2:
The patent eliminates the need for protective triacetylcellulose foils and adhesive layers that are required for conventional H-sheet polarizers. The liquid crystal polymer film is self-sufficient and durable, removing the need for additional protective components that add thickness and complexity.
4Reliability
If protective layers and adhesives are added to conventional polarizers, then moisture resistance and mechanical strength improve, but the total thickness increases beyond acceptable limits
Solution Approach 1:
The patent eliminates the need for protective triacetylcellulose foils and adhesive layers by using inherently durable liquid crystal polymer films. The liquid crystal polymer system is self-protecting and does not require additional layers, achieving both moisture resistance and mechanical strength without increasing thickness.
Solution Approach 2:
The liquid crystal polymer film serves its own protective function, being inherently resistant to moisture and mechanically robust. The system is self-sufficient and does not require external protective layers or adhesives, thereby maintaining thin overall dimensions while ensuring reliability.
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 provides polarizers with high dichroic ratios suitable for LCD applications, enabling thin-film polarizers that are robust, moisture-resistant, and suitable for both inside and outside liquid crystal cell configurations, improving optical performance and mechanical durability.
Implementation Method 1
utilizing smectic phases and specific polymerizable liquid crystals for enhanced orientation and stability
Implementation Method 2
The liquid crystal is aligned by means of photoalignment
Implementation Method 3
a dichroic guest-host polarizer comprising an oriented polymer film including an oriented polymerized liquid crystal host and a dichroic light-absorbing guest dispersed and oriented in the host
Implementation Method 4
Polarization-selective absorption is achieved by means of a dichroic guest which is oriented in the host
Implementation Method 5
The liquid crystal is polymerized by means of UV irradiation
Data Source
AI summary
A dichroic guest-host polarizer comprises an oriented polymerized liquid crystal host and aligned therewith a dichroic guest. The dichroic ratio of the polarizer is about 15 or more. The polarizer may have a small thickness, be manufactured using a wet deposition method, optionally in accordance with a desired pattern, and be provided on the inside of a liquid crystal cell. Polymerizable liquid crystals having a highly ordered mesophase which may be suitable used to obtain highly oriented polymer films such as polarizer films are disclosed.