HUD Laminated Pane With Reflective Film to Minimize Ghost Images
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Solution Overview
Problem
Current head-up display (HUD) projection arrangements using p-polarized radiation suffer from ghost images due to uneven reflection angles across the laminated pane, leading to intensity discrepancies and shifted images, which detract from the clarity and safety benefits of HUDs in vehicle windshields.
Innovation Solution
A laminated pane design featuring a functional reflective film sandwiched between thermoplastic intermediate layers, with a wedge-shaped second thermoplastic intermediate layer having a maximum wedge angle less than 0.20 mrad, ensuring consistent reflection of p-polarized radiation and minimizing ghost images by aligning reflections within the HUD region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective structure is added to the laminated pane to improve HUD image visibility, then the reflection of p-polarized radiation is enhanced, but ghost images appear due to multiple reflection paths
Solution Approach 1:
The reflective structure is segmented into multiple distinct layers: a first reflective layer (50-200 nm aluminum) on the outer pane and a second reflective layer (50-200 nm aluminum) on the inner pane. This segmentation creates separate reflection zones that can be independently optimized to control the reflection paths and eliminate ghost images while maintaining HUD image intensity.
Solution Approach 2:
The reflective layers are positioned at specific locations on different panes (outer pane and inner pane respectively) rather than uniformly across the entire structure. The first reflective layer is applied to the HUD region of the outer pane, while the second reflective layer is applied to the HUD region of the inner pane, creating localized reflection properties that control the optical path and prevent ghost image formation.
2Device complexity
If a single reflective layer is used to simplify the structure, then the device complexity is reduced, but the reflection uniformity across different incidence angles deteriorates
Solution Approach 1:
The reflective function is segmented across two separate layers on different panes rather than relying on a single layer. This segmentation allows each layer to handle specific portions of the reflection requirement, improving overall reflection uniformity across the range of incidence angles while keeping individual layers relatively simple in design.
Solution Approach 2:
The laminated pane employs a composite structure combining two different reflective layers (aluminum layers on outer and inner panes) with the laminated glass construction. This composite approach enables the system to achieve superior reflection uniformity across varying angles by leveraging the complementary reflection properties of the two layers.
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 reduces ghost images, enhancing the clarity and safety of HUDs by ensuring that reflections are aligned, providing a wider and clearer virtual image for the driver without intensity discrepancies, thus improving traffic safety.
Implementation Method 1
Since the incidence angle is typically close to the Brewster angle, and p-polarized radiation is therefore reflected only to a small degree by the glass surfaces
Implementation Method 2
p-polarized radiation
Implementation Method 3
a wedge-shaped second thermoplastic intermediate layer (4), having a maximum wedge angle less than 0.20 mrad
Data Source
AI summary
A laminated pane for a head-up display (HUD) having an upper edge, a lower edge and an HUD region includes an outer pane, a first thermoplastic intermediate layer, a functional film which is suitable for reflecting at least 5% of p-polarized radiation striking the functional film, a second thermoplastic intermediate layer, the thickness of which is variable in the vertical course at least in the HUD region, and an inner pane. The functional film is arranged between the outer pane and the inner pane, the first thermoplastic intermediate layer is arranged between the outer pane and the functional film, the second thermoplastic intermediate layer is arranged between the functional film and the inner pane, and the second thermoplastic intermediate layer has a maximum wedge angle (α) of less than 0.20 mrad.