Windshield Wedge Profile With Reflective Polarizer for HUD Ghost Reduction
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Solution Overview
Problem
Existing heads-up display (HUD) systems in vehicles suffer from ghost images due to reflections from the inner and outer surfaces of the windshield, which reduce the clarity and perceived brightness of the intended virtual image, and current methods require customized thickness profiles or expensive anti-reflective coatings.
Innovation Solution
A standardized windshield wedge profile combined with a weak reflective polarizer is used to reduce ghosting over a larger range of viewing angles, utilizing a reflective polarizer between glass layers to selectively reflect and transmit polarized light, and a wedge-shaped thickness profile to align reflected image rays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflective polarizer is embedded in the windshield, then ghost image reduction is improved, but device complexity increases
Solution Approach 1:
The reflective polarizer is embedded within the windshield laminate structure, nesting the optical component inside the existing glass layers. This integration approach reduces the need for separate external components while maintaining ghost reduction functionality.
Solution Approach 2:
The reflective polarizer acts as an intermediary layer between the interior and exterior glass surfaces, mediating the reflection of ghost images while allowing the main HUD image to pass through. This intermediary component selectively manages different light paths.
2Manufacturing precision
If customized thickness profiles are used, then ghost reduction precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies precise thickness parameters for the reflective polarizer layer and its spacing from glass surfaces (e.g., 0.001-0.006 inches). By standardizing these parameters, the solution achieves consistent ghost reduction performance without requiring customized thickness profiles for each windshield.
Solution Approach 2:
The standardized reflective polarizer embedding approach can be applied universally across different windshield designs and orientations. This multi-functional solution works for various HUD configurations without requiring customization, simplifying manufacturing while maintaining precision.
3Reliability
If anti-reflective coatings are applied, then ghost reduction is improved, but cost increases
Solution Approach 1:
The reflective polarizer is a relatively low-cost, standard optical component compared to specialized anti-reflective coatings. By using this more economical component embedded in the windshield, the solution achieves ghost reduction without the high manufacturing costs associated with custom coatings.
Solution Approach 2:
The solution changes the approach from surface coatings to an embedded layer with specific optical properties. The reflective polarizer's standardized parameters and availability make it a cost-effective alternative to expensive anti-reflective coatings while achieving similar or superior ghost reduction performance.
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 ghosting across various windshield orientations and viewing angles, maintaining image legibility without the need for customized designs or expensive coatings, enhancing HUD image clarity and durability.
Implementation Method 1
the reflective polarizer reflects at least 15% of the incident light having a first polarization state, and transmits at least 60% of the incident light having an orthogonal, second polarization state
Implementation Method 2
the reflective polarizer reflects at least 15% of the incident light having a first polarization state
Implementation Method 3
For at least one first location within the predetermined region of the active display region, the emitted image may include a first emitted image ray emitted from the first location and incident on the outermost first major glass surface of the windshield at an angle of incidence greater than about 60 degrees
Data Source
AI summary
A heads-up display includes a windshield with a standardized wedge profile and an embedded reflective polarizer and a display. The reflective polarizer is disposed between, and spaced apart from, opposing outermost first and second major glass surfaces of the windshield. The heads-up display forms a virtual image for viewing by the eye of a passenger. An image emitted by the display may include a first image ray emitted from a predetermined region of the display and incident on the outermost first major glass surface of the windshield at an angle of incidence greater than about 60 degrees, with at least 90% of the incident first emitted image ray polarized in a plane of incidence of the first emitted image ray.