Liquid Crystal Diffraction Element for Zeroth-Order Polarization
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Solution Overview
Problem
Existing liquid crystal diffraction elements fail to effectively convert zeroth-order rays into polarized light different from the incidence ray, leading to stray light and decreased image quality in image display apparatuses.
Innovation Solution
A liquid crystal diffraction element with an optically anisotropic layer featuring a non-linear liquid crystal alignment pattern, where the optical axis rotates continuously in a plane, and the width of dark lines in the alignment pattern alternates in a specific manner, allowing conversion of zeroth-order rays into polarized light different from the incidence ray.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional liquid crystal alignment pattern is used, then the device structure is simple, but zeroth-order rays are not converted into different polarized light, causing stray light and decreased image quality
Solution Approach 1:
The patent applies asymmetry by introducing a non-linear liquid crystal alignment pattern where the pitch varies across different regions. Specifically, the alignment pattern has a first region with a first pitch and a second region with a second pitch different from the first pitch. This asymmetric pitch distribution causes zeroth-order rays to experience different optical path differences in different regions, converting them into polarized light with different polarization states from the incident light, thereby reducing stray light without requiring complex additional structures.
2Object-affected harmful factors
If a non-linear alignment pattern with varying pitch is used, then zeroth-order rays are converted into different polarized light, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by dividing the liquid crystal layer into multiple regions with different local characteristics. Each region has a specific pitch value (first pitch in the first region, second pitch in the second region) that is optimized for its local function. This allows different parts of the device to have different optical properties, enabling effective stray light reduction through polarization conversion while maintaining manufacturability through region-specific pitch control rather than requiring precise control across the entire device with a single complex pattern.
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 effectively converts zeroth-order rays into polarized light, reducing stray light and enhancing image quality by removing unwanted rays, thereby improving the performance of image display devices.
Implementation Method 1
an optically anisotropic layer formed of a liquid crystal composition containing a liquid crystal compound; in which the optically anisotropic layer has a liquid crystal alignment pattern in which an orientation of an optical axis derived from the liquid crystal compound changes while continuously rotating
Implementation Method 2
The liquid crystal diffraction element having such a liquid crystal alignment pattern can diffract incident light at an angle depending on a wavelength
Data Source
AI summary
An object is to provide a liquid crystal diffraction element which can convert a zeroth-order ray into polarized light different from an incidence ray. The object is achieved by an optically anisotropic layer having a liquid crystal alignment pattern in which an orientation of an optical axis changes while continuously rotating in one in-plane direction, in which, in a case where a main surface of the optically anisotropic layer is observed with an optical microscope under crossed nicols such that a dark line thicker than dark lines on both adjacent sides is randomly selected, and 80 continuous dark lines are selected with the randomly selected dark line as a first dark line, a width of a dark line at an even-numbered position is narrower than a width of a dark line at an odd-numbered position, which is adjacent to the dark line at an even-numbered position.