Head-up display

From Wikipedia, the free encyclopedia

For other meanings of Hud, see HUD.

For the use of HUDs in computer and video games, see HUD (computer gaming).

HUD of a F/A-18C

HUD of a MiG-29

HUD in a Pontiac Bonneville showing a speed of 47 mph

A Head-Up Display, also known as a Heads-Up Display or simply HUD, is any type of display that presents data without blocking the user's view. This technique was pioneered for military aviation and is now used in commercial aviation, motor vehicle and other applications.

In civil aviation the HUD is known as a Head-Up Guidance System (HGS)

1 History
2 Types
3 Characteristics
4 Projection methods
- 4.1 Automotive and non-military applications
- 4.2 Experimental uses
5 See also
6 External links

[edit] History

Head-Up displays were pioneered for fighter jets and later for low-flying military helicopter pilots, for whom information overload was a significant issue, and for whom changing their view to look at the aircraft's instruments could prove to be a fatal distraction.

HGSs have been in use in commercial aviation since the 1970s, and are now in regular use, notably with Alaska Airlines.

Heads up displays have also been incorporated into automobiles, usually as a secondary display for the most important information from the gauges.

In 1988 the first [publicized or known] Heads up Display was installed by GM into a car built on their all new FWD configured W-body platform, a 1988 Oldsmobile Cutlass Supreme. This car served as the May 1988 Indianapolis 500's Pacecar following modifications to convert it to pacecar specification. An additional 50 custom convertible pacecar replicas commissioned by GM also featured the all new HUD, and were intended to be released to the public. These early HUD units were made by Hughes Aircraft Corporation, a GM subsidiary.

Since 1988 General Motors has offered the Heads Up Displays as an option on the 1989-1994 Oldsmobile Cutlass Supreme, 1989 to present Pontiac Grand Prix, and 1993 to present Pontiac Bonneville, and more recently the Buick LeSabre, Park Avenue, Rendezvous and Aztek.

During the 90's, Heads Up Displays were an option offered in Nissan models including the Silvia family of cars.

In 1999, Automotive HUD technology made a big quality leap with the Chevrolet Corvette. The new Corvette, which uses a HUD to display vehicle speed, engine RPM, Navigation and more, has proven the HUD to be one of its most popular options.

In 2000 Cadillac Premiered an optional night vision driving system as a secondary aid for drivers. It utilizes a monitor set in the dash that displays a generated night vision image of the road, using an infrared camera.

As of 2006 BMW now features the head-up display as an option on their 5 and 7 series vehicles, with more HUDs being anticipated from other European and Japanese OEMs.

[edit] Types

There are two types of HUD:

Fixed, in which the user looks through a display element attached to the airframe or vehicle chassis. Commercial aircraft and motor vehicle HUDs are of this type. The system determines the image to be presented depending on the orientation of the vehicle. The size and weight of the display system can be much greater than in the other type which is:
Helmet-mounted, or head-mounted, in which the display element moves with the user's head. This requires a system to precisely monitor the user's direction of gaze and determine the appropriate image to be presented. The user must wear a helmet or other headgear which is securely fixed to the user's head so that the display element does not move with respect to the user's eye. Such systems are often monocular. One use of this type of HUD is in the AH-64 Apache and in the Norwegian F-16 Fighting Falcons.

[edit] Characteristics

HUDs have in common the following characteristics:

The display element is largely transparent, meaning the information is displayed in contrasting superposition over the user's normal environment.
The information is projected with its focus at infinity. Doing this means that a user does not need to refocus his eyes (which takes several tenths of a second) when changing his attention between the instrument and the outside world.

[edit] Projection methods

The most common means by which current HUDs are implemented is to project the image onto a clear glass optical element ('combiner'). Traditionally, the source for the projected image has been a Cathode Ray Tube (CRT), however newer image sources based on micro-display technologies are now being introduced. Micro-display technologies that have been demonstrated include Liquid Crystal Display (LCD), Liquid Crystal On Silicon (LCOS), Digital Micro Mirrors (DMDs), Organic Light-Emitting Diode (OLED) and Laser.

Some experimental HUD systems work instead by directly writing information onto the wearer's retina using a low-powered laser (see virtual retinal display).

[edit] Automotive and non-military applications

Heads Up Displays have been available as optional equipment in a limited number of car models. They commonly display a digital display of speed in miles or kilometers per hour, and often have an English/Metric control for the displayed unit of speed. Many will include indicators for turn signals, high beams, and basic check gages warnings. More deluxe ones will include convenience indicators for the radio.

A HUD based system that projects a laptop monitor into the view of a vehicle driver also exists. Rather than being projected from below the dash like regular automotive HUDs, it is project from a projector mounted on the rearview mirror onto a special see through screen mounted on the upper center windshield. This device has been marketed to police agencies for use with in-vehicle laptops.

A motorcycle helmet HUD system has also been produced and is commercially available.

Chevrolet Corvette produces cars with HUD included.

[edit] Experimental uses

HUDs have been proposed or experimentally developed for a number of other applications, including:

overlaying tactical information onto the vision of an infantryman (such as the output of a laser rangefinder or the relative location of the soldier's squadmates)
continued experimentaion with HUDs in Automobile, by improving imagery and projections used, as well as types of displays. Questions abound, they are presently illegal in several jurisdictions (where laws prohibiting driver-viewable TV sets currently include HUDs). HUDs are likely to become more common in future vehicles.
In the James Bond story Licence Renewed, Bond's car, a Saab 900 turbo, was fitted with a HUD.
providing surgeons with an enhanced view, showing the results of x-rays or scans overlayed over their normal view of the patient, and thus allowing them to "see" structures normally invisible.
providing an interface for access to a universal network. Cory Doctorow elaborated on this concept in his book Down and Out in the Magic Kingdom.