The function of any visual display is to communicate information to the desired level of accuracy. Most displays used in the vehicle must provide instant data but the accuracy is not always important. Analog displays can provide almost instant feedback from one short glance. For example, if the needle of the temperature gauge is about in the middle then the driver can assume that the engine temperature is within suitable limits.
A digital read-out of temperature such as 98 ° C would not be as easy to interpret. This is a good example of why even when digital processing and display techniques are used, the actual read-out will still be in analog form. Shows a display using analog gauges.
6 shows an instrument display using digital representation. Numerical and other forms of display are, however, used for many applications. Some of these are as follows
Traffic information
Over 25 years have passed since we first watched James Bond use a tracking device, which showed a moving blip across a screen on the dashboard of his Aston Martin. Advances in computer technology and GPS systems have turned this into reality. In California, many motor vehicles have been equipped with a gadget called the Navigator, which helps drivers get to a destination by displaying their vehicle’s location on a glowing green map.
The Navigator, introduced by a company known as Teak, is an electronic road map that calculates the position by means of dead reckoning. Data from a solid-state compass installed in the vehicle’s roof and from sensors mounted on its wheels are processed by a computer and displayed on a dashboard screen. The car’s position is represented as a fixed triangle on a map, which scrolls down as the car moves forward and rotates sideways when it turns.
Toyota already offers a computerized dashboard map on an expensive model sold only in Japan, but many manufacturers are considering fitting these devices in the near future. Jaguar, as part of a project called ‘Prometheus’, in conjunction with other manufacturers, has developed a computerized system that picks up information from static transmitters. This system gives directions and advanced warning of road junctions, signposts, and speed limits
Light-emitting diode displays
If the PN junction of a diode is manufactured from gallium arsenide phosphide (Gasp), the light will be emitted from the junction when a current is made to
LED displays are tending to be replaced for automobile use by the liquid crystal type display, which can be backlit to make it easier to read in the daylight. However, LEDs are still popular for many applications.
Liquid crystal displays
Liquid crystals are substances that do not melt directly from a solid to the liquid phase, but first pass through a par crystalline stage in which the molecules are partially ordered. In this stage, a liquid crystal is a cloudy or translucent fluid but still has some of the optical properties of a solid crystal.
The LCD has many more areas of potential use and developments are ongoing. In particular, this type of display is now good enough to reproduce pictures and text on computer screens.
Vacuum fluorescent displays
A vacuum fluorescent display (VFD) works in much the same way as a television tube and screen. It is becoming increasingly popular for vehicle use because it produces a bright light (which is adjustable) and a wider choice of colors than LED or LCD displays.
This shows that the VFD system consists of three main components. These are the filament, the grid, and the screen with segments placed appropriately for the intended use of the display. The filament forms the cathode and segments the anode of the main circuit.
Last word
The glass front of the display can be colored to improve its readability and aesthetic value. This type of display has many advantages but the main problem for automobile use is its susceptibility to shock and vibration. This can be overcome, however, with suitable mountings.
