HUD Windshield Wedge Angle Profile for Ghost Image Reduction
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Solution Overview
Problem
Conventional head-up displays in vehicles suffer from ghosting and double imaging issues due to the reflection and refraction properties of laminated windshields, where optimizing for one effect often worsens the other, and existing solutions fail to adequately address both issues across varying driver eye positions.
Innovation Solution
A projection arrangement for head-up displays featuring a windshield with a thermoplastic intermediate layer having a variable wedge angle that increases from top to bottom, combined with a modified vertical radius of curvature profile where the maximum curvature is positioned above the HUD reference point, effectively decoupling ghost image and double image effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a wedge angle is introduced to compensate for ghost images in reflection, then ghost image visibility is reduced, but double image effect in transmission is increased
Solution Approach 1:
The patent applies a non-linear wedge angle profile that varies locally across the windshield surface, with different wedge angles in different vertical zones. This allows optimization for ghost image compensation in the HUD area while minimizing double image effects in other regions, particularly by reducing the wedge angle at the top edge of the windshield.
Solution Approach 2:
The patent changes the wedge angle parameter across different regions of the windshield, transitioning from a constant wedge angle to a variable wedge angle profile. Specifically, the wedge angle is reduced at the top edge compared to conventional designs, which simultaneously addresses both ghost image compensation and double image reduction.
2Ease of manufacture
If a constant wedge angle is used throughout the film, then manufacturing is simplified, but the solution is optimized for only a single viewing position
Solution Approach 1:
The patent implements a non-linear wedge angle profile where the wedge angle varies in the vertical direction, with different angles optimized for different eye positions. This allows the windshield to accommodate multiple viewing positions while maintaining reasonable manufacturing complexity through a systematic gradient approach.
3Object-affected harmful factors
If the wedge angle increases from top to bottom to reduce ghost images, then ghost image compensation is improved, but double image effect is intensified
Solution Approach 1:
The patent applies a non-linear wedge angle profile that varies locally across the windshield surface, with different wedge angles in different vertical zones. This allows optimization for ghost image compensation in the HUD area while minimizing double image effects in other regions, particularly by reducing the wedge angle at the top edge of the windshield.
Solution Approach 2:
The patent changes the wedge angle parameter across different regions of the windshield, transitioning from a constant wedge angle to a variable wedge angle profile. Specifically, the wedge angle is reduced at the top edge compared to conventional designs, which simultaneously addresses both ghost image compensation and double image reduction.
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
This configuration significantly reduces ghost images and double vision occurrences, providing improved visibility for drivers by optimizing the wedge angle and curvature profile to accommodate different eye positions and enhance image clarity.
Implementation Method 1
images are projected onto the windshield, reflected there and perceived by the driver as a virtual image
Implementation Method 2
Due to the refraction behavior of the two panes of glass, objects viewed through the pane can also appear as a double image
Data Source
Figure 1~2
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AI summary
The present invention relates to a projection arrangement for a head-up display (HUD), at least comprising a vehicle windscreen (1), comprising an outer pane (2) and an inner pane (3) which are connected to one another by way of a thermoplastic intermediate layer (4), with an upper edge (O) and a lower edge (U) and an HUD region (B), wherein the vehicle windscreen (1) has an installation angle in the range from 55° to 75° and wherein the outer pane (2) and the inner pane (3) each have a thickness of at most 5 mm; and a projector (5), which is directed to the HUD region (B) and generates a virtual image which an observer (6) situated within an eyebox (E) is able to perceive, wherein the windscreen (1) has an HUD reference point (G) where a central beam (M) propagating between projector (5) and centre of the eyebox (E) is incident on the inner pane (3), the thickness of the thermoplastic intermediate layer (4) in the vertical profile between the upper edge (O) and the lower edge (U) being changeable, at least in portions, with a wedge angle (α), wherein the wedge angle (α) is changeable, at least in the HUD region (B), and wherein the windscreen (1) has a vertical radius of curvature (R), which is changeable in the vertical profile (V) between the upper edge (O) and the lower edge (U) through the HUD reference point (G), wherein the maximum of the vertical radius of curvature (R) is situated above the HUD reference point (G) in the portion (V') of the profile (V) between the upper edge (O) of the windscreen (1) and the lower edge (BU) of the HUD region (B).