A head-up display or heads-up display—also known as a HUD—is any transparent display that presents data without requiring users to look away from their usual viewpoints. The pilot being able to view information with the head positioned "up" and looking forward, instead of angled down looking at lower instruments.
Although they were initially developed for military aviation, HUDs are now used in commercial aircraft, automobiles, and other applications.
· VIDEO GENERATION COMPUTER.
IT CONSIST OF CONVEX LENS or CONCAVE MIRROR with a Cathode Ray Tube, light emitting diode, or liquid crystal display at its focus. This produces an image where the light is parallel
The combiner is typically an angled flat piece of glass located directly in front of the viewer, that redirects the projected image from projector in such a way as to see the field of view and the projected infinity image at the same time.
The computer provides the interface between the HUD (i.e. the projection unit) and the systems AND data to be displayed .COMPUTER generates the imagery and symbology by the projection unit .
HUDs are split into four generations reflecting the technology used to generate the images.
§ First Generation—Use a CRT to generate an image on a phosphor screen, having the disadvantage of the phosphor screen coating degrading over time. The majority of HUDs in operation today are of this type.
§ Second Generation—Use a solid state light source, for example LED, which is modulated by an LCD screen to display an image. These systems do not fade or require the high voltages of first generation systems. These systems are on commercial aircraft.
§ Third Generation—Use optical waveguides to produce images directly in the combiner rather than use a projection system.
§ Fourth Generation—Use a scanning laser to display images and even video imagery on a clear transparent medium.