COVER STORY
HEADS UP D
Ying Xiong weighs up the pros and cons of different head-up display solutions for transportation purposes
ashboards in vehicles play an essential role in ensuring the driving is safe and smooth by providing relevant
data such as speed, RPM, oil level, warnings, and so on. But as more and more data are presented on multiple screens in vehicles, critical information can sometimes become swamped or difficult to see. Moreover, glancing between the dashboard and the road can be dangerous, especially when drivers need to focus and keep their heads up.
HEAD-UP DISPLAYS FOR DRIVERS The ability of head-up displays (HUDs) to reduce distraction by showcasing critical information in front of the driver explains why they have
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become increasingly popular in the transportation industry of late. There are two main head-up display technologies: projected HUD and emissive HUD.
PROJECTED HUDS The typical projected HUD solutions include TFT-/micro-LED-display HUD and DLP projector HUD. TFT-/micro- LED-display HUD uses two mirrors to project the images generated from a micro-LED display, while DLP projector HUD consists of a DLP projector, DLP optics, and HUD optics. One major advantage is that the
focal point is adjustable, e.g. 3 metres ahead of the vehicle. Eyes refocus more quickly when the driver’s attention switches from the road to the projected display. The projected content can
be rich and colourful, and the solution is mature as it has been available and tested in the automotive market for years. In terms of disadvantages, the setup
is complex and occupies lots of space (typically 7-10 litres) in the dashboard. A special windscreen/coating is also required and the viewing angles are limited. To complicate things further, the
projector shakes when the vehicle shakes, resulting in blurry images, and they do not work with vertical windows and windscreens, making them unsuitable for buses, RVs, trucks or vans in most cases.
EMISSIVE HUDS As emissive display technologies advance, some are becoming alternative solutions for creating next- generation head-up displays that do not require projected systems. The emissive display technologies that can be used for HUDs include micro-LED, TOLED, and Lumineq in-glass displays.
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