Transparent Screen Cholesteric Liquid Crystal Diffraction
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Solution Overview
Problem
Existing transparent screens suffer from low color reproducibility due to variations in hue when viewed from different observation angles, leading to significant differences in the perceived image color compared to the original.
Innovation Solution
A transparent screen design incorporating two main surfaces with a cholesteric liquid crystal layer, where the spiral axis is inclined relative to one main surface, and a stripe pattern with a bright and dark portion arrangement, providing a half width of the diffraction angle peak of 2 degrees or greater, ensuring consistent color reproduction across various observation positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transflective reflective screen is used to allow background observation, then transparency is improved, but color reproducibility deteriorates due to hue variation with observation angle
Solution Approach 1:
The patent applies parameter changes by controlling the spiral pitch of the cholesteric liquid crystal molecules to match the wavelength of green light (532 nm), and by setting the spiral axis inclination angle within a specific range (10-70 degrees). These parameter adjustments enable the screen to diffract green light effectively while maintaining transparency and improving color reproducibility across different observation angles.
Solution Approach 2:
The patent uses composite materials by combining cholesteric liquid crystal layers with specific spiral structures into the screen. This composite structure, featuring controlled spiral pitch and inclination angles, enables selective diffraction of green light while maintaining overall transparency, thus resolving the contradiction between transparency and color reproducibility.
2Manufacturing precision
If the spiral axis of the cholesteric liquid crystal layer is inclined, then color reproducibility is improved, but structural complexity increases
Solution Approach 1:
The patent simplifies the inclined spiral axis structure by defining specific parameter ranges: spiral pitch of 0.05-0.5 μm and spiral axis inclination angle of 10-70 degrees. By establishing these concrete parameter boundaries, the patent transforms a complex structural requirement into controllable manufacturing parameters, reducing device complexity while maintaining color reproducibility.
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 suppresses wavelength dependence of light strength, maintaining original hue visibility regardless of the observation position, thereby enhancing color reproducibility and image fidelity.
Implementation Method 1
a half width of a peak observed in a distribution indicating strength with respect to a diffraction angle of a primary diffraction light emitted from the other main surface
Implementation Method 2
at least one cholesteric liquid crystal layer including a liquid crystal compound, in which in a cross-sectional view of the cholesteric liquid crystal layer in a thickness direction, a spiral axis derived from the liquid crystal compound
Data Source
AI summary
The present disclosure provides a transparent screen including two main surfaces, and out of light of which a wavelength incident on one main surface out of the two main surfaces is 532 nm, a half width of a peak observed in a distribution indicating strength with respect to a diffraction angle of a primary diffraction light emitted from the other main surface out of the two main surfaces is 2 degrees or greater.