HUD Windshield Coating for Polarized Sunglass Visibility
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Solution Overview
Problem
Conventional automotive heads-up displays (HUDs) suffer from ghosting due to multiple reflections caused by index mismatches in windshields, and drivers wearing polarized sunglasses cannot see the HUD image effectively due to primarily s-polarized radiation reflection, necessitating a solution to enhance p-polarized radiation reflection and improve visibility.
Innovation Solution
A laminate with enhanced p-polarized radiation reflecting properties, incorporating multiple layers such as metal functional and sacrificial metal layers, phase adjustment layers, and an overcoat, achieving at least 70% luminous transmittance and 10% p-polarized reflectivity, along with a polarized filter to allow p-polarized radiation to pass through.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional windshield structure is used, then manufacturing is simpler and cost is lower, but ghosting occurs due to multiple reflections from index mismatches
Solution Approach 1:
The patent extracts and eliminates the root cause of ghosting by removing the index mismatch interfaces through a integrated coating structure. Instead of adding complex wedge layers, the invention uses a single continuous coating applied to one glass ply that eliminates multiple reflection sources, thereby taking out the harmful reflection interfaces while maintaining simple manufacturing.
Solution Approach 2:
The patent employs composite material structures by combining specific coating materials (such as metal oxides, polymers, or nanocomposites) with the glass substrate to create a integrated windshield structure. This composite approach provides both optical functionality (reducing ghosting) and structural integrity without requiring additional separate components.
2Device complexity
If conventional windshields reflect primarily s-polarized radiation, then the structure is simpler, but drivers wearing polarized sunglasses cannot see the HUD image
Solution Approach 1:
The patent changes the optical parameter of polarization reflection by designing the coating structure to reflect p-polarized radiation instead of s-polarized radiation. This is achieved by controlling the coating thickness, refractive index, and angular characteristics to shift the polarization state of reflected light, thereby enabling HUD visibility for drivers wearing polarized sunglasses without complicating the overall windshield structure.
Solution Approach 2:
The patent applies local quality by creating specific zones or patterns in the coating with different optical properties. The coating is designed to have particular polarization-selective reflection characteristics in the HUD projection area while maintaining other desired properties in different regions of the windshield, allowing targeted improvement of HUD visibility without affecting overall windshield performance.
3Adaptability or versatility
If additional coatings are applied for solar control and antenna functionality, then these functions are added, but a third reflection occurs creating a third ghost image
Solution Approach 1:
The patent merges multiple functions (solar control, antenna functionality, and ghosting reduction) into a single integrated coating structure. Instead of applying separate coatings that would create additional reflection interfaces, the invention combines these functionalities in one continuous coating layer or multi-layer structure applied to a single glass ply, thereby eliminating the third ghost image while maintaining all desired functions.
Solution Approach 2:
The patent creates a universal coating structure that simultaneously provides solar control, antenna functionality, and ghosting reduction. This multi-functional coating is designed to perform multiple roles: controlling solar radiation transmission, enabling antenna operation through conductive properties, and eliminating parasitic reflections, thereby reducing the need for separate specialized coatings.
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 laminate effectively projects a HUD image visible to drivers wearing polarized sunglasses by enhancing p-polarized radiation reflection, reducing ghosting, and ensuring high luminous transmittance and reflectivity.
Implementation Method 1
An enhanced p-polarized reflective coating is located over at least a portion of at least one of the surfaces of the first ply and/or the second ply. When the laminate is contacted with radiation from a radiation source, the radiation having p-polarized radiation, at an angle of 60° relative to normal of the laminate, the laminate exhibits a luminous transmittance using standard illuminate A (LTA) value of at least 70% and a reflectivity of the p-polarized radiation of at least 5%
Implementation Method 2
along with a polarized filter to allow p-polarized radiation to pass through
Implementation Method 3
the laminate exhibits a luminous transmittance using standard illuminate A (LTA) value of at least 70%
Data Source
AI summary
A laminate including a first ply having a first surface and a second surface, where the first surface is an outer surface of the laminate; a second ply having a third surface facing the second surface and a fourth surface opposite the third surface, where the fourth surface is an inner surface of the laminate; an interlayer between the plies; and an enhanced p-polarized reflective coating positioned over at least a portion of a surface of the plies. When the laminate is contacted with radiation having p-polarized radiation at an angle of 60° relative to normal of the laminate, the laminate exhibits a LTA of at least 70% and a reflectivity of the p-polarized radiation of at least 10%. A display system and method of projecting an image in a heads-up display is also disclosed.