Cholesteric Liquid Crystal Dot Optical Member for Head-Up Display Viewing Angle
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Solution Overview
Problem
Current head-up display systems have a narrow viewing angle range for projected images due to specular reflection, and existing solutions either fail to expand this range effectively or result in blurred front scenery from particle scattering.
Innovation Solution
A member for displaying projected images is developed, comprising a first and second base material with an optical member featuring cholesteric liquid crystal dots on a substrate, which provide a striped pattern and high reflectivity in an oblique direction, enhancing the viewing angle and transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmission type screen member is used to expand the viewing angle range, then the viewing angle range is expanded, but the front scenery appears blurred due to haze caused by particle scattering
Solution Approach 1:
The patent applies local quality by creating microlens arrays with specific refractive indices and focal lengths in different regions of the windshield. Each microlens is positioned at a specific location with tailored optical properties to control light reflection angles locally, thereby expanding the viewing angle without causing widespread haze that would blur the front scenery.
Solution Approach 2:
The patent changes optical parameters by using microlenses with different refractive indices and focal lengths to control the reflection of projection light. By adjusting these parameters, the system expands the viewing angle range while maintaining clear visibility of the front scenery, avoiding the haze problem associated with particle scattering.
2Illumination intensity
If a head-up display system uses a member for displaying a projected image with high transmittance, then the transmittance is improved, but the reflectivity of projection light in oblique direction is reduced
Solution Approach 1:
The patent segments the windshield into multiple regions, each equipped with microlenses having different optical characteristics. This segmentation allows different portions of the windshield to perform different functions: some regions prioritize transmittance for clear front scenery visibility, while others enhance reflectivity for projection light in oblique directions, thereby resolving the contradiction between transmittance and reflectivity.
Solution Approach 2:
The microlenses act as intermediaries between the projection light and the windshield glass. These microlenses with specific refractive indices and focal lengths mediate the interaction by redirecting projection light at appropriate angles while maintaining high transmittance for visible light, thus achieving both high transmittance and adequate reflectivity for oblique projection light.
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 achieves a wide viewing angle with high reflectivity and transmittance, allowing for clear image display without blurring, addressing the limitations of existing technologies.
Implementation Method 1
the cholesteric structure imparts a striped pattern formed of bright portions and dark portions in a cross-sectional image of the cholesteric liquid crystal dot taken by a scanning electron microscope
Implementation Method 2
the optical member includes a plurality of cholesteric liquid crystal dots provided on a substrate, the cholesteric liquid crystal dot is formed of a liquid crystal material having a cholesteric structure
Data Source
AI summary
Provided is a member for displaying a projected image, including: a first base material; a second base material; and an optical member, in which at least one optical member is disposed on a surface of the first base material or the second base material, the optical member includes a plurality of cholesteric liquid crystal dots, the cholesteric liquid crystal dot is formed of a liquid crystal material having a cholesteric structure, the cholesteric structure imparts a striped pattern formed of bright portions and dark portions in a cross-sectional image of the cholesteric liquid crystal dot taken by a scanning electron microscope in a direction perpendicular to a substrate, the dot includes a portion where the height thereof successively increases to the maximum height thereof from an end portion toward the center thereof, an angle between a normal line with respect to a line formed by the first dark portion from the surface of the dot on a side opposite to the substrate and a line representing the surface of the is in a range of 70° to 90° in this portion of the cross-sectional image, and a reflection center wavelength of the dot is in a range of 400 to 1000 nm.