HUD Glass Polarization Design to Eliminate Ghost Images
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional head-up display systems in vehicles suffer from double and triple image phenomena due to S-polarized projection light reflections, leading to unclear HUD images and poor visual comfort, especially when drivers wear sunglasses, and the presence of a transparent conducting layer exacerbates this issue.
Innovation Solution
A head-up display glass comprising an outer glass sheet, thermoplastic interlayer, and inner glass sheet, with a transparent conducting layer that includes multiple metal and dielectric layers, is designed to reflect a mix of S-polarized and P-polarized light, using a wedge-shaped interlayer to align images and reduce ghosting, while maintaining heat insulation and electric heating functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a transparent conducting layer is added to the head-up display glass for heat insulation and electric heating functions, then thermal comfort is improved, but the triple image phenomenon occurs making the HUD image more blurred
Solution Approach 1:
The patent changes the polarization state parameter of the projection light from S-polarized to P-polarized light. This parameter change causes the light to reflect differently at the glass surfaces and transparent conducting layer, eliminating the offset between multiple reflected images and solving the triple image phenomenon while maintaining heat insulation functionality
Solution Approach 2:
The patent converts the harmful reflection effect that causes multiple offset images into a beneficial single clear image by using P-polarized light. The same transparent conducting layer that causes the triple image problem with S-polarized light becomes effective for heat insulation without causing image offset when P-polarized light is used
2Ease of manufacture
If S-polarized projection light is used for head-up display, then the projection device can be easily manufactured, but double image phenomenon occurs leading to poor visual comfort
Solution Approach 1:
The patent changes the polarization parameter of the projection light from S-polarized to P-polarized. This single parameter change resolves the double image phenomenon caused by differential reflection at glass interfaces, while P-polarized light maintains compatibility with existing projection device manufacturing
3Adaptability or versatility
If P-polarized light is used for projection, then drivers wearing sunglasses can see the HUD image, but the projection device complexity increases
Solution Approach 1:
The patent changes the polarization parameter to P-polarized light, which has different transmission characteristics through sunglasses compared to S-polarized light. This allows HUD images to be visible to drivers wearing sunglasses, and the complexity increase is minimal as it primarily involves optical parameter adjustment rather than major device redesign
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 effectively eliminates ghost images, improves visual comfort and driving safety by ensuring clear HUD images even with sunglasses, and maintains thermal and visual comfort through reduced ghost image brightness and improved heat insulation.
Implementation Method 1
The projection light can also be reflected by the transparent conducting layer to form a third offset image
Implementation Method 2
The thermoplastic interlayer has a wedge shape
Data Source
Figure 1~2
Figure 3
AI summary
The present application relates to a head-up display glass and a head-up display system. The head-up display glass includes an outer glass sheet, a thermoplastic interlayer, and an inner glass sheet that are laminated together, and further includes a transparent conducting layer. The transparent conducting layer includes a first metal layer, a second metal layer, a third metal layer, and a fourth metal layer that are sequentially laminated together, with thicknesses satisfy 0.7≤Ea4/Ea1≤1.2. The head-up display glass has a reflectance of at least 15% to projection light incident from the fourth surface at an angle of incidence of 65°, and 40% to 80% of the projection light is S-polarized light and 20% to 60% of the projection light is P-polarized light.