Head-up displays in motor cars

Head-up displays (HUDs) are widely used in military aircraft to project a CRT display into a pilot´s line of sight as he looks out of the aircraft cockpit. The HUD focuses the display image near to infinity to avoid the pilot having to refocus his eyes from viewing the outside world to read the display. A combiner plate is located between the pilot and the cockpit window to reflect the displayed image into the pilots´ line of sight. Initial research into extending the use of HUD technology to motor cars is described. The potential benefit of a HUD to the driver is discussed, and some of the factors to be considered in the design of practical systems. Suitable technologies for the display source, projection optics, and combiner are considered. Integration of the combiner into the car windscreen may be required in practice. Advantages offered by the use of a holographic optical element as the combiner are discussed