Vehicle HUD Optics Using Dielectric Films Against Solar Damage
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Solution Overview
Problem
Existing head-up display systems face challenges in maintaining image quality and protecting liquid crystal display elements from solar light damage due to the collection of solar light by concave mirrors, particularly in augmented reality HUD systems.
Innovation Solution
The system employs a dielectric multilayer film on the concave mirror and correcting optical elements to selectively reflect or transmit light based on polarization direction and wavelength, blocking or reducing incident solar light without compromising image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light polarizing member is pasted on a glass substrate to block polarized component of incident solar light, then the liquid crystal display element is protected from solar light damage, but it is difficult to secure flatness and the quality of display images is reduced
Solution Approach 1:
The patent replaces the mechanical pasting method with a direct formation method using dielectric multilayer films. Instead of pasting a light polarizing member on a glass substrate, the invention forms dielectric multilayer films directly on optical elements (mirror or lens) through vapor deposition or sputtering processes. This substitution eliminates the flatness issues caused by pasting while achieving the same light blocking function through optically precise dielectric layers.
Solution Approach 2:
The patent uses composite dielectric multilayer film structures consisting of multiple layers with different refractive indices and thicknesses. These composite structures are designed to selectively reflect specific wavelengths and polarization components of solar light while maintaining optical clarity. The multilayer configuration allows precise control over optical properties without compromising the flatness or quality of the underlying optical element.
2Area of stationary object
If the size of the concave mirror is increased to enlarge the region where driver can watch virtual images, then the display region is expanded, but much more solar light is collected and the liquid crystal display element is damaged
Solution Approach 1:
The patent applies local quality by making different parts of the optical system have different optical properties. The dielectric multilayer films are formed on specific optical elements (mirror or lens) with locally optimized thickness and refractive index profiles. This allows the system to block harmful solar light in specific regions while maintaining high transmission for display images in other regions, enabling larger mirror sizes without increasing damage risk.
Solution Approach 2:
The patent changes optical parameters (refractive index, film thickness, layer structure) of the dielectric multilayer films to achieve wavelength-selective and polarization-selective blocking. By adjusting these parameters, the system can block concentrated solar light from larger mirrors while allowing display images to pass through, effectively decoupling mirror size from damage risk.
3Reliability
If dielectric multilayer film is formed on optical element surface to selectively reflect/transmit light, then solar light blocking is improved, but the device complexity increases
Solution Approach 1:
The patent merges the solar light blocking function with the existing optical elements by forming dielectric multilayer films directly on mirrors or lenses. Instead of adding separate blocking components, the protective function is integrated into the optical elements themselves. This merging approach enhances solar light blocking performance while minimizing increases in device complexity, as the films become part of the existing optical path.
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
This configuration effectively blocks or reduces solar light, preventing damage to the liquid crystal display element and maintaining image quality by using dielectric multilayer films to manage polarized light components.
Implementation Method 1
the dielectric multilayer film having a property that selectively reflects/transmits light in a desirable polarizing direction or with a desirable wavelength
Implementation Method 2
dielectric multilayer film having a property that selectively reflects/transmits light in a desirable polarizing direction
Implementation Method 3
dielectric multilayer film having a property that selectively reflects/transmits light in a desirable polarizing direction or with a desirable wavelength
Data Source
AI summary
The information display apparatus has a housing with an opening and a transparent cover formed on the opening, the includes image-light generating means configured to housing generate image light that displays the image information and an optical system configured to allow a driver of the vehicle to recognize image information based on the image light from the image-light generating means as a virtual image in front of the windshield. When S-polarized light on the windshield is assumed to be a first polarized wave while polarized light that orthogonally crosses the S-polarized light in a polarizing direction is assumed to be a second polarized wave, the image-light generating means is configured to generate the image light made of the first polarized wave, and a transmittance/reflectance control means blocks a part of the first polarized wave and the second polarized wave of incident external light entering the housing from the opening.