Polarization Rotary Interlayer for HUD Ghost Image Reduction
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Solution Overview
Problem
Conventional windshields with HUD systems experience ghost or double images due to secondary reflections, which are not effectively addressed by existing solutions like dielectric coatings or tapered interlayers, and these solutions often compromise adhesion or optical quality, and are not suitable for multiple vehicle types or driver heights.
Innovation Solution
An interlayer comprising a plasticized poly(vinyl acetal) polymer with a polarization rotary optical film, such as a half wave plate, between two polymer layers, where the optical film is disposed between the polymer layers and includes a phosphate plasticizer, enhancing optical quality and reducing ghost images across various vehicle types and driver heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a dielectric coating is applied to the windshield surface to reduce ghost images, then the ghost image brightness is reduced, but the coating interferes with interlayer adhesion to glass substrates causing optical distortion
Solution Approach 1:
The patent introduces a polymer interlayer as an intermediary substance between the glass substrate and the dielectric coating. This interlayer serves as a mediator that prevents direct contact between the coating and glass, thereby maintaining adhesion while still allowing the coating to function in reducing ghost image brightness. The polymer layer acts as a buffer that preserves the functional relationship between components without direct bonding.
2Object-affected harmful factors
If a tapered interlayer with constant wedge angle is used to align reflected images to a single point, then ghost images are reduced for a specific driver position, but the solution is not effective for multiple driver heights and vehicle types
Solution Approach 1:
The patent transitions from a static, fixed wedge angle design to a dynamic, variable wedge angle design. The interlayer now incorporates multiple regions with different wedge angles that can adapt to different driver positions and vehicle types. This dynamic configuration allows the system to optimize ghost image reduction for various driving conditions rather than being locked into a single geometric parameter.
Solution Approach 2:
The patent applies the principle of local quality by creating different wedge angle regions within the interlayer. Each local region has a specific wedge angle optimized for particular driver positions or vehicle configurations. This spatial variation in geometric properties allows the single interlayer component to serve multiple functions and adapt to diverse application scenarios.
3Ease of manufacture
If the windshield has uniform and consistent thickness to simplify manufacturing, then manufacturing is easier, but secondary reflections create ghost images that degrade optical quality
Solution Approach 1:
The patent employs composite material structure by combining the polymer interlayer with dielectric coating materials in a multi-layer configuration. This composite approach allows the system to maintain the manufacturing simplicity of uniform thickness while introducing functional layers that optically interfere with secondary reflections. The composite structure integrates the ease of manufacturing with the optical performance requirements.
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 significantly reduces or eliminates ghost images by optimizing the refractive indices and polarization conversion, providing improved optical, acoustic, and visual properties while maintaining adhesion and handling efficiency.
Implementation Method 1
An interlayer comprising a plasticized poly(vinyl acetal) polymer with a polarization rotary optical film, such as a half wave plate, between two polymer layers
Implementation Method 2
The solution significantly reduces or eliminates ghost images by optimizing the refractive indices and polarization conversion
Data Source
AI summary
An interlayer comprising a first polymer layer, a polarization rotary optical film and optionally a second polymer layer, and multiple layer panels formed from such interlayers. The panels may exhibit desirable optical properties, including, for example, less image “ghosting.” when used as part of a heads-up-display (HUD) display panel for use in automotive and aircraft applications.