Liquid Crystal Device Using Photoreactive Mesogens for Alignment-Free Beam Steering
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Solution Overview
Problem
Traditional liquid crystal beam steering devices require alignment layers like polyimide, which are costly to produce and can't handle non-uniform substrates, such as those with optical gratings or lens structures, leading to issues like mura, contamination, and temperature sensitivity.
Innovation Solution
A liquid crystal device with opposing transparent substrates, a liquid crystal switching layer comprising polymerized photoreactive mesogens and nematogenic compounds, and an electrode structure, where one or more substrates have an optical grating or lens structure, eliminating the need for additional alignment layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional alignment layers like polyimide are used in liquid crystal beam steering devices, then the liquid crystal molecules can be aligned properly, but production costs increase and the devices cannot handle non-uniform substrates effectively
Solution Approach 1:
The patent removes the separate alignment layer (polyimide) from the device structure by integrating alignment functionality directly into the liquid crystal composition through photoreactive mesogens. This extraction eliminates the need for costly alignment layer production and deposition processes while maintaining effective molecular alignment.
Solution Approach 2:
The patent combines the alignment function with the liquid crystal material itself by incorporating photoreactive mesogens into the liquid crystal composition. This merging creates a unified system where the liquid crystal molecules perform both the optical function and the alignment function, eliminating the need for separate alignment layers.
2Manufacturing precision
If traditional alignment layers are used, then alignment can be achieved on uniform substrates, but non-uniform substrates with optical gratings or lens structures suffer from mura, contamination, and temperature sensitivity
Solution Approach 1:
The patent applies local quality by enabling different regions of the liquid crystal composition to respond independently to local substrate features. The photoreactive mesogens allow each local area to self-align according to its specific substrate topology (flat, grating, or lens structure), providing adaptability to non-uniform substrates without compromising alignment quality.
Solution Approach 2:
The patent utilizes parameter changes through photoisomerization of the photoreactive mesogens upon UV irradiation. This chemical parameter change allows the liquid crystal molecules to reorient and adapt to various substrate geometries, enabling compatibility with non-uniform substrates while maintaining effective alignment.
3Manufacturing precision
If polyimide alignment layers are used, then liquid crystal alignment is achieved, but the production process becomes complex and time-consuming
Solution Approach 1:
The patent applies preliminary action by pre-incorporating photoreactive mesogens into the liquid crystal composition before device assembly. This preliminary preparation eliminates the need for post-assembly alignment layer deposition and rubbing processes, significantly simplifying the manufacturing workflow and improving production efficiency.
Solution Approach 2:
The patent replaces the mechanical rubbing process traditionally used to align polyimide layers with a photochemical alignment mechanism. UV irradiation induces photoisomerization of the photoreactive mesogens, causing automatic molecular reorientation without mechanical contact, thereby eliminating complex mechanical alignment steps and improving productivity.
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 reduces production costs, improves image quality, and allows for the use of non-uniform substrates, enhancing the performance and versatility of liquid crystal beam steering devices.
Implementation Method 1
The alignment is achieved by a photoisomerization of the stabilisers according to the invention upon irradiation with ultraviolet light
Implementation Method 2
In the presence of an electric field, LC directors can be re-oriented, due to both the optical and dielectric anisotropies of the LC molecules, resulting in refractive index modulation (bi-refringence)
Implementation Method 3
In the presence of an electric field, LC directors can be re-oriented, due to both the optical and dielectric anisotropies of the LC molecules
Data Source
AI summary
The invention relates to a liquid crystal device comprising at least two opposing transparent substrates, at least one liquid crystal switching layer sandwiched between said opposing substrates comprising one or more polymerised photoreactive mesogens of formula I,R11-Sp11-X11[-A-Z]o-A11-CY11═CY12[—C═O]x[—O]y-A[-Z-A]p—X21-Sp21-R21 Iwherein R11, R21, A11, A, Z, X11, X21, Y11, Y12, Sp11, Sp21, o, p, x and y have one of the meanings as given in claim 1, and one or more nematogenic compounds, an electrode structure provided on one or both of the opposing substrates, wherein one or more of said substrates are additionally provided with an optical grating or a lens structure adjacent to the LC switching layer. The invention is further related to a method of production of said liquid crystal device, to the use of said Liquid Crystal device in various types of optical and electro-optical devices, and to electro-optical devices comprising the liquid crystal device.