The good old “light bulb”, in other words the thing that my physics teacher always corrected to “lamp” with an annoyed look on his face (and which burnt your fingertips when you unscrewed it), seems almost ancient today. At least at home. Hardly anyone still buys conventional power wasters; there are enough alternatives. In vehicles the technology isn’t following as fast because of other requirements – but it’s following none the less. Today LEDs are everywhere, from back to front. But what are they and what can they do? In the last part of our little history of light we summarized the different stages.
The principle of the light emitting diode is known. The same physics teacher who looked annoyed when someone said bulb also mentioned something about semiconductors with p layers and n layers later on. In actual fact, since as early as the 80s there have been areas of application for small LEDs which emit light if a voltage is applied to them. Mostly in red, yellow, green and orange because of their nature. And with a long life, very low energy consumption and less heat than their filament counterparts. In 1992, Cadillac first used LED technology in the third braking light, and this technology has been on a roll ever since. Just one year later an American physicist developed the blue light emitting diode and all of a sudden any light color was possible in theory.
While in the beginning brightness still left a lot to be desired – because with increasing current the lifetime of the components was also reduced significantly – the first rear lights, brake lights and indicators were developed in LED technology from the start of the new millennium. In 2004, Audi was the first manufacturer in the world to use white LEDs as daytime running lights in its A8 W12 sedan. The first real LED front headlights made an appearance in a Lexus in 2007, and in 2008 the Audi R8 had the first full LED headlights with combined dipped beam and high beam. Since then almost all manufacturers have been following suit, with production prices also reaching acceptable levels for small and mid-range vehicles.
What makes LED technology so sexy? On the one hand, the low energy consumption compared to filament lamps which mainly heat their surroundings. This results in a lifetime that is more than three times as long, and that alone justifies the higher price. But what’s more interesting is the combination of LED clusters (matrices) with intelligent measuring and control electronics. This allows for a combination of, say, 24 individual LEDs to shine always at full power as a headlight. When a car approaches, the electronics only switch off the LEDs that dazzle the driver of the oncoming car. So the object is basically masked out. And there’s always more light on other parts of the road so obstacles and hazards can be recognized earlier. Brilliant.
For the Golf VI with standard halogen headlights, the Osram team has specifically developed brand new LEDriving XENARC headlights which also contain a healthy portion of LEDs. Probably best to say goodbye to the light bulb now. After all, my physics teacher has also retired by now, but nobody is thinking of retiring the LED anytime soon.