Patent attributes
A head-up display system suitable for an aircraft. The head-up display including an image source arranged outside the desired field of view of an observer and where the intensity of symbols of the image source are modulated differ depending on their perceived position relative to the horizon line. A light source is arranged for providing light to an image source which is arranged to modulate the light of the light source thereby creating an image for the head up display. A brightness control unit have inputs for vehicle pitch- and roll angle, and a calculator configured to calculate, based on the pitch and roll angles, the current position in the image of a virtual horizon line, corresponding to the real horizon line as perceived by the observer, and for controlling the brightness of symbols above the virtual horizon line to be different from the brightness of symbols below the line.
