Cholesteric Liquid Crystal Layer Tilt Control for High Diffraction
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Solution Overview
Problem
The existing cholesteric liquid crystal layers in AR glasses suffer from low diffraction efficiency, leading to a decrease in the amount of reflected light.
Innovation Solution
A cholesteric liquid crystal layer with a specific optical axis tilt angle and tilt angle variation in the thickness direction, along with a method of forming the layer using a liquid crystal composition and controlled exposure steps, to enhance diffraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional cholesteric liquid crystal layer is used in AR glasses, then the structure can be formed with standard manufacturing processes, but the diffraction efficiency is low leading to decreased reflected light
Solution Approach 1:
The patent applies parameter changes by controlling the optical axis tilt angle to be within a specific range (5° to 30°) and by controlling the tilt angle variation in the thickness direction to be within 10° to 40°. These specific parameter ranges optimize the diffraction efficiency and increase the amount of reflected light compared to conventional cholesteric liquid crystal layers without such precise control.
2Productivity
If the optical axis tilt angle is increased to improve diffraction efficiency, then more light can be reflected, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent employs preliminary action by establishing a method of formation that includes specific exposure steps and temperature control conditions before the final product is manufactured. The liquid crystal composition is applied, and exposure is performed under controlled conditions (temperature, time, intensity) to pre-determine the optical axis tilt angle and tilt angle variation, making the manufacturing process more controllable and repeatable.
Solution Approach 2:
The patent implements feedback through measurement and evaluation steps that monitor the optical axis tilt angle and tilt angle variation during and after the formation process. By measuring these parameters and comparing them against the target ranges (optical axis tilt angle: 5°-30°, tilt angle variation: 10°-40°), the manufacturing process can be adjusted to maintain precision and optimize diffraction efficiency.
3Productivity
If the tilt angle variation in the thickness direction is controlled to enhance diffraction efficiency, then light guidance is improved, but the device complexity increases
Solution Approach 1:
The patent uses parameter changes to control the tilt angle variation in the thickness direction within a specific range (10° to 40°). By adjusting this parameter along with the optical axis tilt angle (5° to 30°), the patent optimizes light guidance efficiency and diffraction performance without requiring complex structural modifications, thus improving performance while managing device complexity.
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 proposed cholesteric liquid crystal layer achieves high diffraction efficiency, improving light reflection and guidance in AR glasses.
Implementation Method 1
A general cholesteric liquid crystal layer reflects incident light by specular reflection
Implementation Method 2
a cholesteric liquid crystal layer that is obtained by immobilizing a cholesteric liquid crystalline phase
Implementation Method 3
the cholesteric liquid crystal layer has a liquid crystal alignment pattern in which a direction of an optical axis derived from a liquid crystal compound changes while continuously rotating in at least one in-plane direction
Implementation Method 4
a method of forming a cholesteric liquid crystal layer comprising: applying a liquid crystal composition including a liquid crystal compound and a chiral agent to an alignment film
Data Source
AI summary
Provided are a cholesteric liquid crystal layer having high diffraction efficiency, method of forming the same, a laminate, light guide element, and image display device including the cholesteric liquid crystal layer. The cholesteric liquid crystal layer obtained by immobilizing a cholesteric liquid crystalline phase, in which the cholesteric liquid crystal layer has a liquid crystal alignment pattern having a direction of an optical axis from a liquid crystal compound changes while continuously rotating in at least one in-plane direction, in a cross-section observed with SEM, bright portions and dark portions are tilted, where a tilt angle of a direction in which in-plane retardation is minimum with respect to a normal line in a slow or fast axis plane is θ2, an absolute value of an optical axis tilt angle φ is “sin θ2=n·sin φ (n represents an average refractive index of the cholesteric liquid crystal layer)” is 5° or more.