Head-up-Display
The head- up display (HUD; literally " head -up display " ) is a display system in which the user can maintain his head position and viewing direction, because the information is projected in its field of view. The users include pilots, more recently, motorists and others.
Introduction
For pilots of combat aircraft such systems already exist since the 1940s. In Germany they were known as reflex sight ( target device ). Some thirty years later created systems that could be called complex windscreen projectors. Typical feature for a windscreen projector, the second disc in the cockpit, can be projected onto which various information. Today, the head-up display is the single most important indicator in the cockpit. The HUD displays information from a variety of sources, such as avionics, radar and weapons systems, all in a compact, manageable form. For the head- up display, the pilot has a selection of different modes available which he can choose depending on the particular job or the state of his mission. Each mode supports the pilot in a very specific task, be it for example in navigation, the use of different missiles or during the landing approach.
In the 1980s and 1990s, there were at General Motors in the U.S. in different car models a black and white head-up display with fixed displays are not configurable, in which the driver such as the current speed always had in view without the view turn of the road will need to. Even with Nissan, there were already some models, such as the Nissan 240SX.
From 2001, a color display came in the Corvette from General Motors for the first time used.
As the first European manufacturer BMW brought a system developed by Siemens VDO Automotive AG Head -up display in the automobile sector in a large scale in the presented in 2003 5 Series and 6 Series model ranges on the market in 2005, followed by PSA with the Citroën C6.
Meanwhile, head-up displays with different manufacturers on offer.
Cabinets older arcade machines often include a head-up display, as this by shifting the heavy picture tube in the socket with the center of gravity of the machine moves down and the machine is more durable. Instead of a semi-transparent glass plate a normal mirror is installed in the line of sight of the player. With the introduction of TFT screens in the slot machine technology, this application has become rare.
In current computer games general status indicators with head-up display, however designated, which do not belong to the virtual environment, but are statically positioned at the edges of the visual field. Other computer programs are increasingly being equipped with head-up displays.
Operation of a head-up display
Head -up displays are generally composed of an imaging unit, an optical module and a projection screen.
The imaging unit generates the image. The optics module with collimator and diversion directs the image on the screen. This surface is a reflecting, light- transmitting plate. The user of the windscreen projector thus provides the mirrored information to the imaging unit while the real world behind the disc. In aircraft engineering small special picture tubes are used which generate the appropriate image. Picture tubes produce a very large luminosity, thus will not require any additional light source.
The virtual image produced can be projected so that it can be detected with one eye ( monocular ) or both eyes ( binocular ). Binocular HUDs have a higher visibility range than monocular. The virtual image is always projected into infinity. The pilot of a jet adjusted before starting with the height adjustment of his seat to look through the HUD.
As a light source LEDs are used today. The brightness of the image is controlled in dependence on the ambient light on a photo sensor. The image is generated by a high-resolution color TFT display. In CRTs two different techniques for image representation can be used. One is the bright oscillographic (vector ) representation and on the other it is the television technology (row ) representation.
Information content of a head- up displays
The important information in a HUD can be divided into:
- Static information and
- Contact analogue information.
Static information
Static information are those that are always in the view of the driver at the same location. Examples are the vehicle speed and the engine speed. The driver has the feeling that the information on a vertical plane can be seen in for example to the bonnet. On the plane there are such things as height and speed, or the weapons load. This is quite different, depending on which mode the avionics system is being used (navigation, radar or, for example near a dogfight ).
Analog Contact Information
Contact Analog information display elements that are the driver appears in its current view so that he feels as if they are an integral part of the environment. Thus, a navigation arrow appear as if he were lying on the street. In the case of safety distance beam, this means that the driver's speed dependent, a bar is displayed in the windshield area, indicating him how much distance he must stick to the vehicle ahead. In combat aircraft already optically visible target is additionally marked by a luminous circle, for example. This indicates that the sensor systems of the machine (radar, IR) have detected the target and accompany it. Plus a host of other information relating to the target will still be displayed (projection, distance, friend - foe identification ).