An official document that describes how the emerging LED lighting technology has affected the design of the recent Audi models, becoming an important styling element, and how LEDs will change the vehicle’s lighting concept in the next future.

Audi Pikes Peak quattro concept

Five years ago, at the North American

International Auto Show in Detroit, Audi presented the Pikes Peak quattro concept study.

This SUV, which provided the inspiration for today’s Audi Q7, had the world’s first

fog lights equipped with high-performance light-emitting diodes.

Integrated into the

broad bumper as striking strips of light, the fog lights were also aesthetically pleasing and very

popular with the public. Soon thereafter, the 12-cylinder Audi A8 went into series production as the world’s

first vehicle with LED daytime running lights.

Today all new Audi

models are recognizable at a glance thanks to LED daytime running lights, not only during the day but also at night.

Each Audi has its own personality in terms of lighting: the Audi A4 has a sweeping light strip which expresses elegance, while that of the Audi R8 radiates strength and dominance.

The LED technology

A light-emitting diode, or LED, is a semiconductor device –

just a square millimeter in size – which can convert electrical energy directly into light with a very high efficiency.

Audi Q5 – Technical illustrations of the LED lighting units

The first LED headlights introduced with the Pikes Peak

concept generated 18 lumens per watt.

For the sake of comparison, an ordinary household light bulb generates

about 20 to 25 lumens per watt. A modern passenger vehicle’s xenon headlights, on

the other hand, are very energy-efficient and create some 80 lumens per watt.

Audi Shooting Brake Concept

The next generation of

white high-performance LEDs will hit the market next year with 100

lumens per watt, thus surpassing the efficiency of xenon lights for the first time.

Today’s xenon and LED headlights are four times more energyefficient

than halogen headlights.

By 2018, LED technology should be about eight

times more efficient than halogen light. In addition, LEDs excel due to their practically indefinite service life and react up to ten times more quickly than traditional

incandescent bulbs.

“Light-emitting diodes are similar to

computer chips. Every two years there’s an increase in output of about 30 percent,” explains Berlitz, “and we’ll soon be able to create so much light with LEDs that

entirely new applications will become possible.”

Digital light , as Berlitz calls this new light technology, can be made more or less bright

electronically and precisely adapted to a driver’s needs. Audi developers are

convinced that future generations of headlights will react to weather conditions, a

vehicle’s speed, the distance between vehicles, and potentially dangerous objects.

Developers tightly bundle several light-emitting diodes to create modules known as LED

arrays.

These arrays are extremely flat, very compact and require much less space

than conventional light sources such as halogen bulbs or xenon burners.

Because of

this, and thanks to reflectors as well as sophisticated electronic controls, it is possible

to realize very complex lighting functions in the tightest of spaces. Cornering light, for

example, has traditionally been executed via complex mechanical means in

headlights.

Energy Efficiency

LEDs can also reduce a vehicle’s fuel

consumption. Vehicles’ conventional low-beam headlights, taillights, and license-plate

illumination consume some 200 watts – which the alternator must constantly

generate.

By comparison, a mere 15 watts is required to power the new Audi A4’s

LED daytime running lights, that equates to a decrease of about 0.2 liters of

fuel per 100 kilometers and about 4 grams fewer CO2 emissions per kilometer.

This advantage will be more and more evident when daytime running lights become mandatory in the European Union

in May 2011.

LED lights in design

The tiny light sources present designers with spectacular opportunities. Stefan Sielaff,

Audi’s Head of Design, explains: “LEDs unlock the door to unrealized design

possibilities for exterior design and interiors alike.”

For example, a number of lightemitting

diodes can be combined to create various shapes, which can ultimately result

in a distinctive visual appearance.

The taillights of the Audi A6 Avant are likely the

best-known example of any tail end. These light-emitting diodes in a ring-shaped array have become every bit as instantly recognizable as the sweeping LED daytime

running lights at the front end of the Audi A4.

Audi A6 Avant

Headlights naturally play a pivotal role in a vehicle’s light design. An appealing front end with one-of-a-kind lights makes a car as well as its personality and the brand recognizable at a glance.

Sielaff adds: “LED daytime running lights epitomize this fact.

Every light design is different, yet there’s no mistaking that every single vehicle is an

Audi.

"Our daytime running lights cemented the visible persona of Audi models on the

road and hone our progressive, sporty design.”

Today different configurations of LED daytime running lights now permit distinct

differences among the Audi models – even in the dark.

A strip of light can be

designed to underscore a vehicle’s character, just as eyeliner emphasizes an eye.

This fundamentally alters the body language of Audi models.

“The lighting configuration of yesteryear – the radiator grille along with the round lights – called to

mind the face of a friendly bear,” notes André Georgi, Senior Designer of Lighting

Systems.

“The LED daytime running lights for the A Series, e.g. on the A4

and A5, look determined, elegant, and dynamic.

"The lights on the Audi Q5 and Audi

Q7 appear especially broad and powerful.

"And the LED daytime running lights on the

R8 symbolize the horns of a bull charging full speed ahead, bursting with vigor and pride.”

The Audi R8 is the spearhead of Audi’s light

strategy and is optionally available with the world’s first all-LED headlights.

In addition

to the daytime running lights, the turn signals as well as low-beam and high-beam

headlights are all executed by means of light-emitting diodes.

Huhn explains: “A lot of people

initially viewed this development as a mere marketing gimmick. Yet everyone who has

seen these lights in action is not only astonished by the excellent output, but also

thrilled with the homogenous distribution of light and the agreeable, daylight-esque

color of the light."

Audi’s light strategy also benefits from something quite different, namely a

psychological phenomenon: “Bright light created by small, compact light sources is

unpleasant for the human eye. The combination of headlights and LED daytime

running lights enlarges the light source, thus eliminating a nuisance,” explains Georgi.

Ideas and visions

From left to right: Dr. Wolfgang Huhn, Head of the Light and Visibility

Department, André Georgi, Senior Designer Lichtsysteme and

Stephan Berlitz, Head of Lighting Technology and Electronics

At Audi the

design process is initiated by developing and defining a vehicle’s character. The light

designers and engineers from Technical Development play a hands-on role in this

process from the word go. For example, one of the engineers – fittingly nicknamed “The Bridge” by his colleagues – works right in the middle of the Design Department.

Conversely, a lot of the technically relevant headlight components are designed by

Technical Development. This close rapport ensures that the departments confer with

one another every day.

As a vehicle’s exterior takes shape, the proportions of the headlights and the taillights

are defined. Georgi says: “It’s a truly intensive process for us to develop new

headlights; every idea and every vision from Technical Development and Design

come together.”

Audi’s light designers turn to industrial design and architecture when they require

inspiration for new ideas.

In fact, more and more architects are integrating high-tech LEDs into their plans for new buildings, thus joining a worldwide shift toward energy-efficient lighting.

Experts forecast that LEDs, energy-efficient and maintenance-free

sources of light, will also become the first choice for indoor lighting.

Another source of inspiration for light designers is nature.

“Nature often shows us the way, allowing us to learn just how simply and effectively

processes can be executed," explains the light designer Georgi.

The most recent

example of this is the taillights we developed for the Audi A1 Sportback Concept, which was inspired by the

lattice structure of a dragonfly’s wing.

The design of the taillights impressively

demonstrates the relative simplicity required to construct a very large, stable and light

surface.

Georgi says: “With our bionic design, we transferred this constructional

conception to the Audi A1 concept’s taillights, which needed to be lightweight

because they are integrated in the tailgate.”

The headlights of the Audi A1 Sportback Concept are an additional illustration of nature permeating Audi design.

Reminiscent of an open pine cone, reflector shells arranged successively in

concentric circles harness the light of each individual diode to create lighting which is

powerful and consistent.

The headlights in the middle, on the other hand, are shaped

like blossoms.

The future

Stephan Berlitz, Audi Head of Lighting

Technology

and Electronics

Audi developers think that the future generations of headlights will provide "the right light for every driving situation".

Huhn explains: “We’re striving to

create intelligent headlights and taillights which think and anticipate in the interest of

enhancing a driver’s safety and comfort.”

For example, there are already high-beam

headlights in pre-series development which will allow drivers to navigate roads at

night without temporarily blinding oncoming drivers.

This is made possible by a

variable distribution of light: An electronic system continuously calculates the distance

to any approaching vehicles to ensure that the road ahead is ideally illuminated at all

times – without irritating oncoming drivers.

Interior lighting

LEDs also present new opportunities for interior lighting. Similar to interior

architecture, lighting scenarios are imaginable which would make it safer to operate

the vehicle at night, render the interior considerably roomier, or impart a certain

atmosphere.

The optional interior lighting package with ambient lighting in the Audi A8 is an example. It gives the

possibilities for customizing the interior lights: the driver can dim the light and

configure various lighting profiles via the MMI.

André Georgi, Senior Designer of Lighting System at Audi

These profiles respond as appropriate

to certain driving situations – when a vehicle’s interior is illuminated by lighting within

cities, for example, or becomes dark on unlit rural routes.

When it comes to the lighting in vehicle interiors, developers are confronted with few

limits. Safety and comfort are top priorities.

Berlitz explains: “Think of a mountain hut

at night. As you’re passing through an alpine meadow, you spot the warm light

glowing through the hut’s windows. The light triggers that same cozy sensation you

feel when you arrive home.”

“Just imagine: You press a single button on your remote control

and the entire vehicle springs to life. The ‘headlight eyes’ awaken and an inviting light

fills the vehicle’s interior as if to say: Welcome home!”

(Source: Audi)