HUD stands for Heads-Up Display. Heads-Up displays operate by projecting an image, usually from an LCD onto a piece of glass or for instance, onto the windshield of a car above the instrument cluster. They are becoming widely used in automotive applications to display information such as speed, fuel gauge and driver assistance warnings. The image is usually projected in parallel with the drivers line of sight, as if it were floating on the road in front. This allows the driver to remain focused on the road at all times.
The LED driver in the backlight of the LCD controls the luminous intensity of the HUD. It is important that these LED Drivers have a wide dimming range so the HUD's luminous intensity can vary throughtout the day, or as needed.