Digital Speedometer and Odometer
Unlike the analog speedometer, the digital speedometer is operated by
a vehicle speed sensor. It puts out electrical pulses to be processed
by the computer. The computer turns on segments of a display to form
numbers, which is the speed of the car.
The digital odometer chip can be replaced if it is defective without
replacing the entire speedometer cluster, but a new odometer will
register zero mileage. If the entire cluster has to be replaced,
however, the old odometer chip can be transferred to the new cluster,
displaying the current mileage, because the chip retains the mileage
in its memory.
As far as the instruments of a car, new devices are being considered
which allow certain information, for example, the vehicle's speed, to
be displayed by creating an image on the windshield. The image would
appear to be some distance ahead of the car, so that the driver need
not re-focus his eyes to read it. The so-called heads-up display
device would therefore allow the driver to be able to monitor his
speed and other functions of the car without having to scan downwards
from his forward view.