ABSTRACT
For many decades, automobiles and many other road vehicles had used essentially the same basic technology for their drive systems and passenger cabins, apart from a gradually evolving stream of improvements to performance and passenger comfort. In the past 20 years or so, however, far more advanced vehicle technology has started to take a major hold. Almost all low power panel/instrument illumination lights in vehicles, originally using old-fashioned tungsten filament lamps, are now replaced by light-emitting diodes (LEDs). LEDs are compact, have far greater reliability, are more rugged and consume far less power. LEDs have also, for several years, been the lamp of choice for medium power vehicle side lights and as intermittent indicators for direction change or braking. For many years, LEDs were not bright enough to replace the main vehicle headlights, which require intense sources to provide their closely collimated light beams.
