Under the microscope: Head-up display: Keeping your eyes on the road

Feb 2, 2018
Stuttgart/Amsterdam

The optional head-up display is a new feature in the A-Class. Important information is projected onto the windscreen directly in the driver's field of vision, reducing distraction from the traffic situation. There is also less eye fatigue for the driver, as the eyes do not constantly have to refocus between close-up and long-distance vision. Also new in this vehicle class is configuration via the head-up display itself.

A system of lenses and mirrors projects a full-colour image measuring around 24 x 8 centimetres into the windscreen. It appears to float above the bonnet at a distance of around 2.5 metres. The resolution of more than 60 pixels per degree of viewing angle ensures a needle-sharp image. The driver can adjust the height of the virtual image so that it can be easily viewed. In vehicles with seat memory function this feature stores the individual settings.

The head-up display is activated using the left touch-control button in the steering wheel. It is configured via a settings menu in the display itself, a first in this vehicle class. The driver is able to configure the display according to personal preferences and priorities. Depending on the equipment level and personal settings, it shows e.g. navigation instructions, vehicle speed, speed limits or the settings for cruise control or Active Distance Control DISTRONIC.

A light sensor located near the top edge of the roof automatically adjusts the brightness of the head-up display to the exterior lighting conditions. Brightnesses of 12,000 cd/sq. m. plus can be achieved on sunny days. Since the contrast ratio is better than 1000:1, the system produces a high-quality display even in the dark.

To avoid double images caused by reflection at the outer and inner boundary surfaces of the windscreen, this includes a wedge-shaped composite membrane if the vehicle is equipped with the head-up display. It superimposes the secondary image, which is produced on the outer surface, onto the primary image. The head-up display was already taken into consideration during the design of the new dashboard, and the appropriate space was allowed for it.

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