Reflective LCD Alignment Layers Using Self-Aligning Monomer
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Solution Overview
Problem
The existing reflective liquid crystal display devices using cholesteric liquid crystals require multiple alignment layers, leading to increased material costs, fabrication time, and reduced contrast ratio and color purity due to misalignment and thickness issues, as well as increased driving voltage and transmittance reduction.
Innovation Solution
A reflective liquid crystal display device is fabricated using a single irradiation of a polarized ultraviolet ray to form alignment layers after the cholesteric liquid crystal layers are formed, reducing the number of fabrication steps and misalignment, and improving contrast ratio and color purity by using a self-alignment monomer with cholesteric liquid crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If six alignment layers are individually formed on six substrates, then each alignment layer can be formed with controlled thickness, but the total thickness increases to about 600 nm reducing transmittance, and misalignment occurs during attachment
Solution Approach 1:
The patent merges the formation of six separate alignment layers into a single alignment layer formation process. By using a self-aligning monomer that forms alignment layers on all six substrates simultaneously through one coating and curing step, the patent eliminates the need for individual alignment layer formation on each substrate, thereby reducing total thickness while maintaining alignment precision.
Solution Approach 2:
The self-aligning monomer automatically forms alignment layers with proper orientation on all substrates without requiring manual alignment or multiple fabrication steps. The monomer's molecular structure enables it to self-organize and create consistent alignment directions across all six substrates through a single process, eliminating the need for external alignment adjustments.
2Manufacturing precision
If six alignment layers are formed individually and then attached, then each layer can be optimized, but fabrication time and fabrication cost increase due to multiple steps
Solution Approach 1:
The patent combines six separate alignment layer formation operations into a single operation by applying a self-aligning monomer composition that simultaneously forms alignment layers on all six substrates. This merging of operations reduces fabrication time and eliminates multiple coating and curing cycles while maintaining the ability to optimize alignment properties through the monomer's inherent self-aligning characteristics.
Solution Approach 2:
The self-aligning monomer serves multiple functions simultaneously: it forms alignment layers on all six substrates, provides optical compensation, and ensures proper alignment orientation without requiring separate processing steps for each substrate. This multi-functionality consolidates multiple fabrication operations into a single universal process.
3Reliability
If six alignment layers are formed with standard thickness of about 100 nm each, then sufficient anchoring energy is provided, but total thickness of about 600 nm reduces transmittance
Solution Approach 1:
The patent merges six separate alignment layers into a single alignment layer with reduced thickness. The self-aligning monomer forms this consolidated alignment layer that provides sufficient anchoring energy for the liquid crystal molecules while minimizing total thickness to improve light transmittance, eliminating the need for six thick individual layers.
Solution Approach 2:
The patent changes the thickness parameter of the alignment layer from 600 nm (six layers of 100 nm each) to a reduced thickness of about 20 nm by using a self-aligning monomer. This parameter change maintains adequate anchoring energy while significantly improving transmittance properties.
4Adaptability or versatility
If three stacks are attached to form a reflective LCD device, then color selection is achieved, but optical axes become misaligned and contrast ratio decreases
Solution Approach 1:
The patent merges the alignment layer formation across three separate stacks into a single unified process. By applying a self-aligning monomer that forms alignment layers on all substrates simultaneously, the patent ensures that optical axes are properly aligned across all three stacks, eliminating misalignment issues that occur during separate attachment processes while maintaining color selection capability.
Solution Approach 2:
The self-aligning monomer automatically ensures proper optical axis alignment across all three stacks without requiring manual alignment or precise attachment positioning. The monomer's molecular self-organization properties create consistent alignment directions that compensate for attachment variations, maintaining high contrast ratio and color purity.
5Manufacturing precision
If reactive mesogen is used to remedy alignment misalignment, then alignment is improved, but driving voltage increases
Solution Approach 1:
The patent changes the material parameter by using a self-aligning monomer instead of reactive mesogen. This material substitution maintains high alignment accuracy while reducing driving voltage requirements, as the self-aligning monomer creates more efficient alignment structures that require less energy to maintain the liquid crystal orientation.
Solution Approach 2:
The self-aligning monomer serves as a temporary alignment aid during fabrication that achieves its purpose of creating proper alignment without requiring the continuous high voltage needed by reactive mesogen systems. Once alignment is established, the system operates at lower voltages.
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 approach simplifies the fabrication process, reduces costs, and enhances the alignment of optical axes, resulting in improved contrast ratio, color purity, and reduced driving voltage while maintaining sufficient transmittance.
Implementation Method 1
The LCD device displays an image using an optical anisotropy and a polarization property of a liquid crystal molecule
Implementation Method 2
The LCD device displays an image using an optical anisotropy and a polarization property of a liquid crystal molecule
Implementation Method 3
three cholesteric liquid crystal layers selectively reflecting red, green and blue colored lights
Implementation Method 4
forming an alignment layer through a single irradiation of an ultraviolet ray after a cholesteric liquid crystal layer is formed
Implementation Method 5
using a self-alignment monomer with cholesteric liquid crystals
Data Source
AI summary
A reflective liquid crystal display device includes: first to fourth substrates spaced apart from and parallel to each other; a first stack including a first pixel electrode, a first alignment layer, a first common electrode, a second alignment layer and a first cholesteric liquid crystal layer between the first and second alignment layers; a second stack including a second pixel electrode, a third alignment layer, a second common electrode, a fourth alignment layer and a second cholesteric liquid crystal layer between the third and fourth alignment layers; a third stack including a third pixel electrode, a fifth alignment layer, a third common electrode, a sixth alignment layer and a third cholesteric liquid crystal layer between the fifth and sixth alignment layers; and a fourth stack including a first mode electrode, an ion storing layer, an electrolyte layer, an electrochromic layer and a second mode electrode sequentially on the first substrate.