HUD Windshield Wedge Angle Minimization
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Solution Overview
Problem
Conventional head-up display (HUD) projection arrangements face challenges in minimizing ghost images due to the reflection of projector images on both surfaces of the windshield, requiring complex and expensive production of wedge-shaped thermoplastic films with large wedge angles.
Innovation Solution
A projection arrangement for HUDs featuring a windshield with a thermoplastic intermediate layer having a variable thickness in the HUD region, achieving a maximum wedge angle of less than 0.3 mrad, produced by stretching a film of constant thickness, which allows for a larger projection distance and reduced ghost image issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a large wedge angle is used in the thermoplastic film to minimize ghost images, then the ghost image problem is reduced, but the production complexity and cost increase significantly
Solution Approach 1:
The patent changes the wedge angle parameter from the conventional large value (typically 0.5 mrad or more) to a small value (less than 0.3 mrad). This parameter change resolves the contradiction by demonstrating that small wedge angles are sufficient to minimize ghost images in contact analog HUDs with large projection distances, while being much simpler and less expensive to produce than large wedge angle films
Solution Approach 2:
The patent applies the principle of partial action by using only the minimum necessary wedge angle (less than 0.3 mrad) to achieve adequate ghost image minimization. Instead of using the conventional excessive wedge angle (0.5 mrad or more), the patent shows that a smaller, partial amount is sufficient for contact analog HUDs with projection distances of at least 5 m, thereby simplifying production while maintaining effectiveness
2Object-affected harmful factors
If a large wedge angle is used in the thermoplastic film, then ghost images are minimized, but the production cost increases due to complex extrusion processes
Solution Approach 1:
The patent changes the wedge angle parameter to a small value (less than 0.3 mrad), which fundamentally alters the manufacturing approach. Small wedge angle films can be produced using standard extrusion dies with simple adjustments, whereas large wedge angle films require complex wedge-shaped extrusion dies and precise temperature control, significantly reducing production cost and complexity
3Length of stationary object
If the projection distance is increased to at least 5 m for contact analog HUD, then the HUD region is enlarged and more optical information can be displayed, but the wedge angle must be precisely controlled to minimize ghost images
Solution Approach 1:
The patent changes the wedge angle parameter to a small value (less than 0.3 mrad) that is well-suited for large projection distances of at least 5 m. This parameter change reduces the sensitivity to manufacturing precision requirements compared to conventional small projection distances, as the smaller wedge angle provides a more forgiving tolerance range while still effectively minimizing ghost images across the enlarged HUD region
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 solution simplifies and economizes the production of HUD windshields while effectively minimizing ghost images and double images in transmission, enabling a larger projection distance and improved aesthetic and aerodynamic design.
Implementation Method 1
the thickness of the intermediate layer is variable, at least in sections, in the vertical course between the upper edge and the lower edge of the windshield... The angle between the two surfaces of the film is referred to as a wedge angle
Implementation Method 2
the projector irradiates a region of the windshield, where the radiation is reflected in the direction of the observer (driver), by which means a virtual image is generated
Data Source
AI summary
A projection arrangement for a head-up display (HUD) is presented. The arrangement has a vehicle windshield that includes an outer pane and an inner pane bonded to one another via a thermoplastic intermediate layer. The vehicle windshield has an upper edge, a lower edge, and an HUD region. The thickness of the thermoplastic intermediate layer in the vertical course between the upper edge and the lower edge varies, at least in the HUD region, according to a wedge angle. The arrangement also has a projector that is aimed at the HUD region to generate a virtual image at a projection distance of at least 5 m. According to one aspect, a vertical radius of curvature in the HUD region is at least 6 m and a maximum value of the wedge angle is less than or equal to 0.3 mrad.