Laminated Windshield Structure for Brighter HUD Images
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Solution Overview
Problem
The use of HUD devices in vehicles leads to a double image phenomenon, where the main image and sub image appear shifted, causing discomfort and difficulty in viewing the image light.
Innovation Solution
A windshield configuration is introduced, featuring an inner glass plate with higher visible light transmittance and a thinner thickness than the outer glass plate, along with an interlayer containing a reflective film that increases the luminance of the image light. This configuration reduces the attenuation of image light and enhances visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective film is disposed on the interlayer to reflect image light, then the visibility of the main image is improved, but a double image phenomenon occurs causing discomfort
Solution Approach 1:
The patent applies local quality by creating asymmetric optical properties between the inner and outer glass plates. The inner glass plate has higher visible light transmittance and smaller iron oxide content to reduce sub-image formation, while the outer glass plate has lower transmittance and higher iron oxide content to minimize reflection. This localized differentiation of material properties resolves the double image issue while preserving main image visibility.
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the iron oxide content and thickness of the glass plates. The inner glass plate has total iron oxide (T-Fe2O3) of 0.01-0.5 wt% and thickness of 0.5-2.0 mm, while the outer glass plate has T-Fe2O3 of 0.1-1.0 wt% and thickness of 1.0-3.0 mm. These parameter optimizations adjust the optical characteristics to suppress sub-image visibility while maintaining main image luminance.
2Object-affected harmful factors
If the inner glass plate has higher visible light transmittance to reduce sub image, then the sub image visibility is reduced, but the overall light transmission increases
Solution Approach 1:
The patent converts the potentially harmful effect of high light transmission into a benefit by strategically positioning the high-transmittance inner glass plate. The inner glass plate's high visible light transmittance (70-90%) allows sufficient light to reach the reflective film for main image formation, while its specific optical properties prevent sub-image formation. The outer glass plate's lower transmittance compensates for overall light control.
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 proposed solution effectively inhibits the discomfort caused by the double image phenomenon, improving the visibility of the image light by increasing its luminance and reducing the visibility of the sub image.
Implementation Method 1
a reflective film having a reflective surface capable of reflecting the image light, and a luminance of the image light reflected by the reflective surface is increased
Implementation Method 2
the inner glass plate has a visible light transmittance larger than a visible light transmittance of the outer glass plate
Implementation Method 3
at least one of the first bonding layer and the second bonding layer contains an ultraviolet absorber and/or an infrared absorber
Data Source
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AI summary
The present invention is a windshield configured to make image light from a head-up display device attached inside a vehicle enter from an inclined direction, including an inner glass plate disposed on a vehicle interior side, an outer glass plate disposed opposite the inner glass plate on a vehicle exterior side, and an interlayer that bonds the outer glass plate and the inner glass plate to each other, wherein the interlayer includes a reflective film having a reflective surface capable of reflecting the image light, and a luminance of the image light reflected by the reflective surface is increased.