Compound HUD Glazing With P-Polarized Ghost Image Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing head-up display (HUD) systems in vehicles suffer from ghost images due to S-polarized light reflections and high thermal radiation transmission, leading to increased production costs and reduced visibility, especially when using wedge films for angle compensation.
Innovation Solution
A composite pane for HUDs utilizing P-polarized radiation with a reflective coating of an electrically conductive silver-based layer and dielectric layers, combined with a second coating to reduce thermal radiation, eliminating the need for wedge films and improving TTS values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If S-polarized light is used for HUD projection, then the image can be projected onto the windshield, but ghost images appear due to reflections at both air-to-glass and glass-to-air transitions
Solution Approach 1:
The patent changes the polarization parameter from S-polarized to P-polarized light. P-polarized light at angles close to the Brewster angle experiences minimal reflection at the glass surface, eliminating the ghost image problem while maintaining HUD visibility. The projector is configured to emit P-polarized radiation at an angle of incidence between 45° and 75°, preferably close to the Brewster angle for the specific glass type.
Solution Approach 2:
Instead of using a wedge-shaped interlayer to geometrically offset the ghost image, the patent creates an optical copy solution by using P-polarized light that naturally avoids reflection at the glass interface. This eliminates the need for the wedge film while achieving the same goal of preventing ghost images.
2Object-generated harmful factors
If wedge films are used to eliminate ghost images, then the ghost image problem is solved, but production costs increase significantly
Solution Approach 1:
The patent extracts and removes the wedge film from the windshield structure. By using P-polarized light, the harmful reflection effect is eliminated without requiring the wedge-shaped interlayer, thereby reducing manufacturing complexity and cost while maintaining the ghost image-free performance.
Solution Approach 2:
The patent replaces the physical wedge film structure with an optical solution using P-polarized light. This substitution eliminates the need for expensive wedge films while achieving the same functional result of preventing ghost images through optical principles rather than geometric structure.
3Illumination intensity
If the windshield has high light transmission, then visibility is good, but too much thermal radiation is transmitted through the glazing
Solution Approach 1:
The patent employs a composite coating structure consisting of multiple dielectric layers with different refractive indices. This composite structure selectively reflects P-polarized visible light for HUD projection while allowing thermal infrared radiation to pass through, achieving both high visible light transmission and thermal energy blocking. The coating includes at least one dielectric layer with refractive index 1.9-2.2 and at least one with refractive index 1.4-1.7.
4Object-generated harmful factors
If P-polarized radiation is used for HUD projection, then ghost images are eliminated, but the windshield requires a reflective coating which may affect thermal properties
Solution Approach 1:
The patent uses a composite dielectric layer structure that is spectrally selective. The coating reflects P-polarized visible light (400-700 nm) for HUD projection while being transparent to thermal infrared radiation (>700 nm). This allows the windshield to maintain good thermal properties without compromising the P-polarized light reflection needed to eliminate ghost images.
Solution Approach 2:
The reflective coating is applied only in the HUD projection area rather than across the entire windshield surface. This localized application minimizes the impact on thermal radiation transmission while providing the necessary P-polarized light reflection for ghost image elimination in the specific region where HUD projection occurs.
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 provides high reflectivity for P-polarized radiation, reduces ghost images, and enhances TTS values by up to 5%, maintaining optimal visibility and thermal comfort without increasing production costs.
Implementation Method 1
The first coating is suitable for reflecting P-polarized radiation and comprises precisely one electrically conductive silver-based layer
Implementation Method 2
the radiation of the HUD projector is P-polarized
Implementation Method 3
a second coating for reducing the transmission of total thermal radiation through the composite pane
Implementation Method 4
A measure of the total transmitted thermal radiation through the pane is described by the so-called TTS value
Implementation Method 5
a first pane and a second pane, which are bonded together via a thermoplastic intermediate layer
Data Source
Figure 1~2
Figure 3A~3B
Figure 4~5
AI summary
The present invention relates to a composite panel for a head-up display, at least comprising a first panel (1) having a first surface (I) and a second surface (II), a second panel (2) having a first surface (III) and a second surface (IV), and a thermoplastic intermediate layer (3), which is arranged between the second surface (II) of the first panel (1) and the first surface (III) of the second panel (2), a HUD area (B), and a first coating (20) for reflecting P-polarized radiation and exactly one electrically conductive layer (21) based on silver, wherein a second coating (30) is provided for reducing the total transmitted thermal radiation.