LED technology is on the way to the European marketplace as manufacturers such as Visteon complete R&D projects

“Technological breakthroughs mean LEDs can now be used for front headlights, giving significant safety, maintenance and vehicle styling advantages”

The end could be near for the electric light bulb in cars as manufacturers move ever-closer to launching the first set of light-emitting diode (LED) front headlamps on a production car. Already used for brake and rear signalling lights and internal lighting in many vehicles – in Europe more than 80% of new cars include some LED components – LED headlights incorporating the dipped beam, main beam, indicator, position light and daytime running light functions are starting to feature in concept cars exhibited at motor shows.

Now, following Halogen (filament bulbs) and Xenon headlights, LED technology is expected to reach the marketplace in Europe within two years as experts at leading manufacturers Hella, Valeo and Visteon complete their research and development projects.

At this year’s Frankfurt Motor Show, Renault’s sports utility vehicle concept, the Egeus, featured “boomerang”- shaped LED headlights incorporating low and high beam, progressive bending light, daytime running lights and turn indicators, developed by Valeo. The company says: “With their small size, powerful light emission, extreme reliability, low energy requirement and record lifespan, LEDs are the technology of the future for automotive lighting. With a light colour close to that of daylight, this technology increases visual comfort and road visibility.

“The electronic LED control unit adapts the quantity of light and orientation of the beam according to the driving conditions. On a winding road, the direction of the beam is electronically managed by a specific function, while on the motorway, the diodes are activated and controlled automatically to provide optimal range without dazzle at all times.”

However, LED technology is not new and is in use everywhere – from traffic signals to surgical lights. But it is only recently that technological breakthroughs mean that it can be used for front headlights, giving significant safety, maintenance and vehicle styling advantages. LEDs light up about 250 milliseconds quicker than bulbs. This does not sound a lot, but at about 60mph it is the equivalent of seven metres in distance – perhaps the difference between seeing and being seen and stopping safely or being involved in a crash.

LED headlamp prototype development has achieved the light equivalent on low beam of Xenon headlamps, which provide more than twice the light of Halogen bulbs whilst consuming half the power. Now, further improvements are promised to achieve the equivalent full beam light. With up to 17 individual LEDs to make one headlamp – many light sources must be arranged to provide necessary night-time and poor weather visibility to create a beam pattern for high beam, low beam, daytime running lights and front fog lights – an ultra-white beam pattern can be generated by aiming each LED as needed.

The electronic LED control unit adapts the quantity of light and orientation of the beam according to driving conditions

“LEDs are long-lasting, having a life span of more than 50,000 hours, which means the headlamps can outlive the life of the vehicle”

An LED is a compact, solid-state semiconductor device that converts electrical energy directly into light. LEDs are mercury-free and need less power, which makes them an environmentally-friendly and highly-efficient light source.

LEDs are also long-lasting, having a life span of more than 50,000 hours – compared to as little as 300 hours for a bulb – which means the headlamps can outlive the life of a vehicle. For drivers this means lower maintenance costs. Depending on configuration, LED-based front lighting sources require up to 40% less power than tungsten bulbs. This allows carmakers to apply the saved energy to other safety or comfort features, say manufacturers. LED-based headlamps are also up to 55% thinner than their non-LED counterparts, which frees up valuable space in the engine compartment or in the grille to add styling options.

Visteon, for example, believes that the introduction of LED front lighting systems could revolutionise car front design and could help designers to “break out of the box” of the traditional, two headlamp front-end design approach. Since LED front lamps do not require a single packaging unit – or “capsule” – car designers could potentially conceal the lights in the grille design so that no lighting source is recognisable during daylight hours, it is suggested. Apart from low power, another issue that has delayed the fitment of LEDs by vehicle manufacturers has been cost, as such technology is more expensive than a light bulb. However, in relation to LED use in high-mounted centre brake lights, a faster system performance has over-ridden cost concerns.

LEDs generate more light than bulbs and as demand increases manufacturing costs will fall — the focus on safety will overcome initial price concerns. Finally, with the production line fitment of LED headlights just around the corner, only regulatory approval is required. By 2008, European Commission approval is expected to have been given for LEDs to be used in front fog lights and on both low and high beam – permission has already been given for LED use for front signalling and daytime running lights.

Initially, LEDs could be combined with both Halogen and Xenon lighting for some front lighting applications in the near future. But, eventually LEDs will dominate, meaning that the days of the conventional light bulb in cars will be numbered.