LED lamps on cars have been around for over twenty years but have only recently featured as a technology used for front lamps. They first appeared in the mid-1980s for use in hi-mount stop lamps, but since then the Light-Emitting Diode (LED) has made steady inroads into replacing the conventional incandescent bulb for automotive lighting. Designers always want to seize the opportunities that any new technology offers for new solutions that simply weren't possible before and lighting is a key area for them to explore.
We've seen LED front lamps on concept cars for some years now but the crossover into production cars has been limited. Audi are the frontrunners, and the firm is now using LED running lamps as a key part of the frontal signature on each of their models. This enables the identity of an A4 to be very different than that of an A5, A8 or TT, for example. Volvo will adopt a similar strategy from 2009 but other automakers are holding back. For main headlamps, only the Audi R8 and Lexus LS600h L use LEDs - and both are high-cost models made in small volumes.
For rear lamps the advantages of LEDs were clear: the ultra-fast on-off illumination meant they offered useful improvements for safety and the much smaller bulb pockets meant they could be packaged more easily. The Maserati 3200GT and the BMW E46 3 series coupé were some of the earliest adopters of LED tail lamps, followed by cars such as the Peugeot 307CC and Jaguar XJ series.
Other advantages of LED lamps include much longer bulb life and lower power consumption than conventional bulbs, and for these reasons we've seen the basic form of LEDs becoming standard fitment for commercial vehicle taillamps and marker lamps. In the future, these benefits will be increasingly important for hybrid or electric vehicles in order to preserve battery power.
But main headlamps on production cars remain a problem. Why?
There are two big disadvantages: cost and heat issues. Indeed, the intense heat issues are a real barrier to wider use of LEDs as main headlamps. Compared with running lamps or rear lamps, a dipped beam or main headlamp is much brighter and generates far more heat. Lamp suppliers such as Hella, Valeo, Lumileds and Osram Sylvania are devising complex systems to remove the heat, including fans, air-conditioned cabin air and water cooling, but these add hugely to costs and complexity for mass production lamps.
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