exterior and interior Led LightingThe Audi A6 is available with three different headlight variants and three different lighting

packages for the interior. The full-LED headlights, which employ the very latest lighting technology

to illuminate the road ahead with a brightness resembling daylight, are a particularly innovative

feature. The LEDs used for the interior lighting add a touch of class with special lighting scenarios,

while LED rear lights put the final touch to the unmistakable appearance of the Audi A6.

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ExtErior lighting

It has become something of a tradition at Audi that the brand’s cars cut a very spe-cial figure out on the road with an unmis-takable night design. With the Audi A6, however, new standards have been set for the design, sophistication and efficiency of vehicle lighting. It is available with three different headlight variants, with customers able to choose between halo-gen, xenon and LED headlights, 1.

Full-lEd hEAdlights

The full-LED headlights on the Audi A6 consist of high-performance LEDs, a series of powerful control units which are networked with the rest of the vehi-cle, precision-designed lens and reflec-tor systems, as well as a housing that has been perfectly conceived down to the finest detail. To keep the headlight unit ventilated and for general thermal management, there is a fan which pre-vents the electronics and light sources from overheating and boosts the con-vection rate.

For optimum light distribution with low beam on there are four one-chip and five two-chip LEDs, which are housed in a total of nine precisely aligned reflector/lens modules. The full-LED headlights in the Audi A6 take night-time driving safety into a whole new dimension.

There is a fully automatic stepper motor for instantaneously adapting the light dis-tribution to the vehicle load levels and any pitching body movements when accelerating and braking. The automatic motorway light increases the range of vision on widened country roads and motorways, with stepper motors raising the light/dark boundary when travelling at higher speeds. Visibility is improved when driving at night by the high-beam light produced using three four-chip LEDs in a free-form reflector system. The LED static cornering light produced by a single four-chip LED illuminates the way ahead highly effectively when turning off the road in bends or into dark narrow streets or courtyard entrances.

To prevent oncoming traffic from being dazzled when entering countries where traffic drives on the other side of the road, the headlights can be switched to tourist mode from the “MMI” system’s “CAR” menu. This light function is realised by deactivating the three asymmetric LED headlight range modules. This does away with the need to either visit the workshop to have mechanical headlight components modified or to mask certain areas of the headlight lens.

All-wEAthEr light

The novel all-weather light is produced with the aid of several electronic and electro-

dipl.-ing. stEphAn BErlitz is responsible for the Development of Lighting Electronics and Lighting Technology innovations at AUDi AG

in ingolstadt (Germany).

dipl.-ing. (Fh) romAn horst is responsible for illumination Electronics in the Audi A6 at

AUDi AG in ingolstadt (Germany).

dipl.-ing. (Fh) toBiAs schwAB is Team coordinator in interior Lights

Development at AUDi AG in ingolstadt (Germany).

dipl.-ing. michAEl mAyEr is responsible for roof Module

Electronics Development within the area of convenience Electronics

Development at AUDi AG in ingolstadt (Germany).

dipl.-ing. (Fh) mArkus mEiEr is responsible for interior Lights

Development for the A6 within the area of interior Lights Development

at AUDi AG in ingolstadt (Germany).

AUThors

1 Exploded diagram of LED headlight

219January 2011 Audi A6

mech anical components. By activating the LEDs appropriately at the same time as adjusting the light/dark boundary by means of the stepper motors, the degree of back-glare when driving in fog and rain is reduced. The road verge is illuminated for a greater distance as well to further increase driving comfort. The introduction of the all-weather light meant that the previous 55 watt halogen fog lights could be omitted on the Audi A6 too. This solution offers considerable benefits. Firstly, there is no colour conflict between the colour tempera-tures of the daylight-like full-LED headlight (5500 K) and the yellowish halogen fog light (3000 K). The difference in energy consump-tion between all-weather light and fog lights is another important point to remember: when the two conventional fog lights are switched on, it drains the energy supply of an additional 110 watts or so of power. The all-weather light, on the other hand, is gen-erated by simply modifying the light distri-bution, meaning that there is no additional power burden. Lastly, the installation space that is freed up in the bumper can be used for the radar sensors for the “adaptive cruise control” (ACC). The new installation posi-tion notably enhances the performance of the ACC system.

lEd turn signAls

The familiar combined LED daytime run-ning light/sidelight function is now supple-mented by an LED turn signal function. The headlight unit in the Audi A6 is therefore characterised by the same, highly homoge-nous appearance using thick-wall technol-ogy for all three lighting functions, and makes optimum use of the available instal-lation space. The daytime running light/sidelight is made up of 24 white LEDs. The turn signal is also generated by 24 LEDs, although these glow yellow. InGaN (indium gallium nitride) LEDs are used for this pur-pose, where the yellow light is produced by phosphorous conversion of blue LEDs. This type of LED has a far lower rate of degrada-tion than conventional AlInGaP (aluminium gallium indium phosphide) LEDs.

The amalgamation of all lighting func-tions within a minimal amount of space combined with the most exacting stand-ards in terms of lighting technology, homo-geneity and design places a whole new set of demands on optical calculation, thermal management, packaging and tooling.

lEd rEAr lights

The two-part LED rear lights, 2, put the final touch to the unmistakable appearance of the Audi A6, both during the day and at night. The LED electronics are character-ised by intelligently designed light activa-tion and diagnosis. Although the life of an LED is considerably longer than that of an incandescent bulb, there is an integral fail-ure detection control to monitor LED opera-tion. The analogue electronics inside the rear light ensure that the individual lighting functions are activated correctly and the required light values maintained, as well as monitoring the individual LEDs.

The tail light is formed by a total of 60 LEDs. Homogeneity and luminous power represent a particular challenge for the lighting technology and design. The light emitted by the LEDs is diverted via 60 reflectors that have been aligned with one another and then distributed through a diffusion lens. The result is a lighting effect that clearly distinguishes the new Audi A6 both within the Audi portfolio and from its competitors.

The brake light and turn signal functions are no less elaborate in their design, with 50 red and 56 yellow LEDs respectively ensuring that all signals from the new Audi A6 can be clearly seen by traffic behind.

intErior lighting

Interior comfort and ambience are increas-ingly becoming a key differentiating factor for car manufacturers’ more luxurious vehicle classes. Interior lighting packages

and ambient lighting concepts make a major contribution to this. The challenge facing the manufacturers here is to empha-sise the portion of interior ambience that is registered subconsciously in order to heighten the customer’s perception of it. Ultimately, the aim is to evolve ambient lighting and interior lighting scenarios into desirable and brand-specific equipment features.

lEd intErior lighting

Unmistakable premium character and sporty travel comfort are the pillars of the interior lighting concept for the Audi A6. Illuminated LED door sill trims, LED cour-tesy lights and lighting scenarios welcome the driver and their passengers, seemingly beckoning them into the vehicle. Under-stated ambient lighting strips in the doors and in the centre console that use indirect LED optical fibres lend the cabin a sense of size and breadth in the dark. Audi uses a cool white colour temperature of 5500 K for all LED interior light sources, which resembles daylight and has a high spectral blue component. As this colour means that the eyes have to adapt less to the brightness, even small doses are enough to make the driver pay more attention when switching their gaze between the road and the interior. Another positive side effect of LED light is that it clearly stands out from the light given off by a conventional bulb. If the “premium LED lighting package” is selected, all other interior light sources are matched for light colour too. This means that LED technol-

2 Two-part LED rear light

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ogy is also used for all the lights which have a function, such as the footwell, vanity mirror and door pocket lights.

By introducing LED technology into the cabin, Audi is extending its approach of establishing and standardising lighting innovations and light design beyond the headlights and rear lights into the interior too. One of the main advantages of LEDs for interior lighting is their compact size compared to conventional lighting tech-nology. This means that they can be fitted into the smallest installation space, for example as a light source for door lighting strips, 3. Whereas previously it was the available space that dictated the position of an ambient light, now design consider-ations can take priority, allowing the interplay between light and form to be orchestrated to perfection.

lighting scEnArios

One of the most striking new features com-pared to the outgoing A6 are the lighting scenarios that form part of the premium LED lighting package’s scope of functions: when the vehicle is unlocked, the interior light spreads from the driver’s seat via the front passenger seat to the rear seats, thereby illuminating the entire cabin. The footwell lighting and the ambient lighting

in the doors are activated too. This stag-gered switch-on of low-level lighting pro-duces the effect of a wave of light expand-ing through the vehicle. With the “coming/leaving home” function, the combined courtesy/door handle lights are addition-ally activated to illuminate the area around the vehicle and the door handles.

When a door is opened, the interior light focuses on the seat next to it, lighting it up (“welcome light”). To maintain a basic level of brightness in the vehicle interior, the surround lighting for the centre console is switched on at a low setting and the ambient lighting in the doors is activated.

When the vehicle is locked, the interior light recedes again, starting from the rear seats and moving back to the front pas-senger seat then the driver’s seat before finally “disappearing” into the steering wheel. Only the courtesy lights in the door handles stay on, supplementing the rest of the exterior lighting and controlled by the “coming/leaving home” function.

With a luminosity in excess of 30 Lux from the LED reading light, homogenised and directed at the relevant seat with opti-mum light distribution, passengers can enjoy the sort of easy, fatigue-free reading that cannot be achieved with conven-tional lighting technology. At the same time, it is important that high-perform-

ance LEDs are operated efficiently and in the optimum power range. Any power and voltage fluctuations in the vehicle’s electrical system provoked by recupera-tion phases, for instance, also need to be compensated for. The improvements in light efficiency during a vehicle’s service life require continuous adaptation of the electronics. Thermal management and electrical power management are funda-mental to energy and light efficiency as well as long LED life in the interior too.

The range of interior lighting packages for the Audi A6 is structured to reflect its premium character. There are two pack-ages, one an extension of the other, which the customer can choose from if they wish to upgrade the already high-quality stand-ard specification. The first lighting package supplements the standard features with LED ambient lighting strips in all doors, entry lights on the rear doors and courtesy lights in the exterior mirrors. The second package – the premium LED lighting pack-age – replaces the conventional lighting technology in the interior light module with LEDs and extends the ambient light-ing features to include indirect surround lighting for the centre console and illumi-nated door sill trims, illumination of the map pocket in the front doors, as well as the welcome scenario described above.

3 interior ambience

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