Cholesteric Liquid Crystal Bandpass Filter Angle Dependence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bandpass filters, particularly those with high and low refractive index layers formed by vapor deposition, are time-consuming, expensive, and exhibit angle dependence in selective reflection wavelengths.
Innovation Solution
A method for producing a bandpass filter using a laminate with light reflective layers formed by immobilizing dextrorotatory and levorotatory cholesteric liquid crystalline phases, combined with a light absorbing layer, which reduces angle dependence and simplifies production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vapor deposition is used to form high and low refractive index layers, then selective reflection wavelength is achieved, but production time increases and cost increases
Solution Approach 1:
The patent replaces the mechanical vapor deposition process with a liquid crystal-based optical system. Instead of physically depositing multiple refractive index layers through vapor deposition, the invention uses cholesteric liquid crystal layers that inherently provide selective reflection through their helical structure, eliminating the time-consuming vapor deposition process while achieving the same optical function
Solution Approach 2:
The patent employs composite material structures combining cholesteric liquid crystal layers with polymer networks. The liquid crystal molecules form a helical structure that provides selective reflection, while the polymer network immobilizes this structure. This composite approach achieves the desired optical properties without requiring multiple vapor-deposited layers, thereby reducing production time and cost
2Manufacturing precision
If vapor deposition is used to form high and low refractive index layers, then selective reflection wavelength is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the expensive vapor deposition equipment and process with a simpler liquid crystal coating and polymerization system. The liquid crystal composition can be applied using conventional coating methods, and the phase transition to immobilize the helical structure occurs through controlled temperature changes rather than requiring complex vapor deposition apparatus, significantly reducing manufacturing cost
Solution Approach 2:
The patent utilizes the phase transition parameter of cholesteric liquid crystals to achieve the desired optical structure. By controlling temperature parameters during the phase transition from cholesteric to isotropic phase and back, the helical structure is formed and immobilized without requiring expensive vapor deposition processes, thereby reducing manufacturing cost while maintaining selective reflection wavelength precision
3Manufacturing precision
If conventional laminate structure is used, then selective reflection is achieved, but angle dependence increases
Solution Approach 1:
The patent uses a composite structure where cholesteric liquid crystal molecules are embedded in a polymer network. This composite configuration creates a rigidified helical structure that maintains its optical properties across different viewing angles, reducing the angle dependence problem inherent in conventional flexible laminate structures
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 method enables the production of bandpass filters with reduced angle dependence and cost-effectiveness by using cholesteric liquid crystal layers and a light absorbing layer, improving reflection and transmission properties across a specific wavelength range.
Implementation Method 1
a liquid crystal compound having a polymerizable group and a dextrorotatory chiral agent to form a coating film and forming a light reflecting layer Xa formed by irradiating the coating film with light and immobilizing a dextrorotatory cholesteric liquid crystalline phase
Implementation Method 2
irradiating the coating film with light and immobilizing a dextrorotatory cholesteric liquid crystalline phase
Implementation Method 3
a light absorbing layer having a maximum transmittance of 70% or more at a wavelength of 700 nm or more and a maximum transmittance of 30% or less at a wavelength of 400 nm or more and less than 700 nm
Data Source
Figure 1~3
Figure 4
Figure 5~6
AI summary
The present invention provides a composition kit which is suitably used for more convenient production of a bandpass filter with reduced angle dependence, a laminate and a method for producing the same, and a bandpass filter. The composition kit of the present invention includes a first composition containing a liquid crystal compound having a polymerizable group and a dextrorotatory chiral agent, a second composition containing a liquid crystal compound having a polymerizable group and a levorotatory chiral agent, and a third composition containing a color material.