Cholesteric Liquid Crystal Reflection Member for HUD Heat Shielding
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Solution Overview
Problem
Head up display devices face challenges in effectively shielding both infrared and visible light for heat protection, as existing solutions that block visible light impair the projected image display function.
Innovation Solution
A reflection member comprising a selective reflection layer and two ¼ wavelength phase difference plates, where the selective reflection layer includes a fixed cholesteric liquid crystal phase with a central wavelength in the visible light range, is used to efficiently shield visible light while allowing projected light to be extracted, thereby reducing damage to optical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If visible light is shielded using conventional heat-shielding means, then heat shielding effectiveness is improved, but the projected image display function is impaired
Solution Approach 1:
The invention segments the light spectrum into different wavelength ranges and applies different reflection strategies: the first cholesteric liquid crystal layer reflects visible light (400-700nm) to provide heat shielding, while the second cholesteric liquid crystal layer reflects ultraviolet light (300-400nm) which is also harmful. This segmentation allows selective shielding of harmful radiation while maintaining transparency to projected light wavelengths
Solution Approach 2:
The invention applies local quality by creating layers with different cholesteric liquid crystal compositions and helical pitches tailored to specific wavelength ranges. Each layer has optimized properties for its designated function: the first layer targets visible light reflection for heat shielding, while the second layer targets UV reflection, allowing each region of the film to have specialized optical properties
2Object-affected harmful factors
If infrared light is shielded to protect optical systems, then heat damage is reduced, but the complexity of the shielding structure increases
Solution Approach 1:
The invention merges multiple heat shielding functions into a single integrated film structure. By combining two cholesteric liquid crystal layers with different reflection characteristics in one film, the invention simultaneously shields against visible light heat radiation and UV radiation, replacing what would traditionally require multiple separate shielding components
Solution Approach 2:
The invention uses composite materials by combining cholesteric liquid crystal layers with different helical pitches and compositions within a single film structure. This composite approach enables the film to exhibit multiple optical functions (visible light reflection, UV reflection) that would require different materials, simplifying the overall shielding system
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 shields visible light and infrared light, mitigating heat-related damage to optical systems while maintaining the integrity of projected image display in head up display devices.
Implementation Method 1
the selective reflection layer includes a layer of a fixed cholesteric liquid crystal phase having a central wavelength of selective reflection at a visible light range wavelength
Implementation Method 2
the selective reflection layer includes a layer of a fixed cholesteric liquid crystal phase having a central wavelength of selective reflection at a visible light range wavelength
Implementation Method 3
two 1⁄4 wavelength phase difference plates, in which the selective reflection layer is disposed between the two 1⁄4 wavelength phase difference plates
Data Source
AI summary
The present invention provides a reflection member including a selective reflection layer; and two ¼ wavelength phase difference plates, in which the selective reflection layer is disposed between the two ¼ wavelength phase difference plates, the selective reflection layer includes a layer of a fixed cholesteric liquid crystal phase having a central wavelength of selective reflection at a visible light range wavelength λi, and the selective reflection layer includes a layer in which a twisted direction of a helix of a cholesteric liquid crystal is only one of right or left as the layer of a fixed cholesteric liquid crystal phase having selective reflection at the wavelength λi. The reflection member of the present invention can be used particularly as a heat shielding member, which can reduce damage to the optical systems due to external light including visible light while efficiently extracting projected light.