Optical Advantages of Thin Window Hybrid Windshields 2018-01-0468

The adoption of head-up displays (HUDs) is increasing in modern automobiles. Yet integrating this technology into vehicles with standard windshield (WS) laminates can create negative effects for drivers, primarily due to the thickness of glass used. The double ghosting in HUD images is typically overcome by employing a wedged PVB between the two glass plies of the laminate. Another solution is to reduce the thickness of the glass without impacting the overall windshield toughness. Although this still requires the use of a wedged PVB to eliminate HUD ghosting, the thinner glass provides opportunity to increase the image size. However, reducing the thickness of a soda-lime glass (SLG) ply or plies in a conventional soda-lime glass (SLG) laminate can significantly impact the robustness of the laminate to external impact events.

This paper will review how a hybrid laminate made from one ply of a relatively thick SLG and a second ply of relatively thin, chemically-strengthened glass, will not only improve the windshield robustness but simultaneously provide better optical performance for HUD applications. Exemplary thin, chemically-strengthened glass can be fusion-formed and demonstrates superior optical and surface qualities compared to float-formed SLG, and typically exhibits greater damage resistance than SLG. When used in a windshield, these lightweight hybrid laminates offer enhanced HUD performance and require a smaller wedge angle. The thickness and wedge angle reduction reviewed in this paper have a significant impact on the ghosting of objects observed in transmission through the windshield. While thick laminates with panoramic shapes suffer from degraded night vision, the use of hybrid laminates significantly reduces the ghosting in transmission. Hybrid laminates can help OEMs move towards more elaborate windshield shapes and assist in improving the vehicle’s aesthetics and aerodynamics.