Vehicle Windshield Anti-Reflective Coating for HUD Ghost Image Reduction
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Solution Overview
Problem
Current head-up display systems in vehicles face challenges with double images due to reflections from the windshield, particularly when trying to achieve a full-color display, as existing anti-reflective coatings struggle to provide anti-reflective properties across the complete visible light spectrum.
Innovation Solution
A vehicle windshield design incorporating a polymer-inclusive interlayer and an anti-reflective coating on either surface of the windshield, with a broad reflectance spectrum matching the strongest light wavelength of the image source, effectively eliminating double images by minimizing reflection across the visible wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-reflective coating is applied to the windshield surface to reduce ghost images, then the visibility of the HUD image is improved, but the coating cannot provide effective anti-reflective properties across the complete visible light spectrum
Solution Approach 1:
The patent applies anti-reflective coatings selectively on specific surfaces (interior surface S4 or exterior surface S1) rather than uniformly across all surfaces. The coating is applied locally to the surface where it most effectively reduces ghost images while maintaining overall system performance. This localized application allows optimization for specific wavelength ranges most critical for HUD visibility.
Solution Approach 2:
The patent modifies optical parameters by introducing anti-reflective coatings with specific refractive indices and thicknesses tailored to reduce reflections at particular wavelengths. By adjusting coating parameters (thickness, material composition), the system optimizes anti-reflective performance for the dominant wavelength range of the HUD display while accepting trade-offs in other spectral regions.
2Strength
If the windshield uses multiple glass substrates with an interlayer to maintain structural integrity, then the windshield strength is improved, but the complexity of the windshield structure increases
Solution Approach 1:
The patent employs a laminated glass structure comprising multiple glass substrates (first substrate with exterior surface S1, second substrate with interior surface S4) bonded together with an interlayer. This composite structure provides enhanced strength, safety, and optical performance while managing the complexity through standardized lamination processes and integrated anti-reflective coating application on specific surfaces.
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 enables a full-color head-up display system by reducing double images, ensuring clear visibility of the virtual image without ghost reflections, while maintaining high visible light transmission and solar control capabilities.
Implementation Method 1
an anti-reflective coating provided on an exterior surface of the first substrate for preventing at least some of the light rays from being reflected off of the exterior surface of the first substrate and toward the viewer
Implementation Method 2
The windshield has an inner surface (surface 4; S4) that can create a first image by reflecting light rays
Data Source
AI summary
Certain example embodiments relate to a vehicle windshield with a head-up display system, including first and second spaced-apart substrates sandwiching a polymer-inclusive interlayer therebetween, and an anti-reflective coating provided on an exterior surface of the first substrate or an interior surface of the second substrate in opposite to the polymer-inclusive interlayer. An image source directing light rays towards one of the substrates, has an light emission profile showing the strongest light strength at a first wavelength, whereas the anti-reflective coating has a broad reflectance spectrum, showing the lowest reflectance at a second wavelength, which substantially matches the first wavelength.