Tapered Windshield Interlayer for Multi-Height HUD Ghost Reduction
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Solution Overview
Problem
Conventional methods fail to provide polymeric interlayers that reduce the HUD projection system, as they are optimized for a single driver height, leading to ghost images for taller or shorter drivers.
Innovation Solution
A windshield with a polymeric interlayer having a HUD region with a tapered vertical thickness profile that includes variable angle zones, minimizing ghost images for drivers of all heights by adjusting the wedge angle profile within 0.10 mrad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a constant wedge angle is used in the interlayer, then the ghost image is minimized for a single driver height, but ghost images appear for drivers of different heights
Solution Approach 1:
The interlayer transitions from a static constant wedge angle to a dynamic variable wedge angle profile that continuously changes across the HUD region. This allows the optical path to be adjusted for different driver eye positions, eliminating ghost images for drivers of varying heights while maintaining clear HUD visibility
Solution Approach 2:
Different regions of the interlayer are assigned different wedge angles tailored to specific driver eye positions. The HUD region is divided into zones with progressively varying angles, where each zone optimizes image alignment for particular viewing heights, providing localized optimization across the entire windshield area
2Measurement precision
If dielectric coating is applied to minimize ghost images, then secondary image brightness is reduced, but adhesion between polymeric interlayer and glass substrates is interfered with
Solution Approach 1:
The polymeric interlayer itself serves as an intermediary optical element with variable wedge angle, replacing the need for dielectric coatings. This eliminates the adhesion problems caused by coatings while achieving ghost image reduction through the engineered thickness variation that controls light reflection paths
Solution Approach 2:
The optical function previously achieved by dielectric coatings (reflectivity control) is replaced by a mechanical/geometric solution - the variable wedge angle profile of the interlayer. This geometric approach manipulates light paths through refraction and reflection controlled by thickness variation, substituting chemical/coating-based optical control with physical structural control
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 windshield effectively reduces reflected double image separation for drivers of varying heights, ensuring clear HUD image visibility regardless of driver height.
Implementation Method 1
A windshield with a polymeric interlayer having a HUD region with a tapered vertical thickness profile that includes variable angle zones, minimizing ghost images for drivers of all heights by adjusting the wedge angle profile within 0.10 mrad
Data Source
Figure 1
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Figure 3
AI summary
A tapered interlayer and windshield employing the same are provided. Unlike conventional windshields, which are optimized to reduce ghost images for a single driver height, the windshields of the present invention may exhibit reduced ghosting for drivers of multiple heights, including very tall or very short drivers, while also providing desirable image clarity for average-height drivers. Windshields as described herein may be used in a variety of applications, including automotive, aircraft, marine, and recreational vehicles that employ HUD projection systems.