c6a6 LED headlights (from audi press)
06-29-2005, 01:06 PM
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c6a6 LED headlights (from audi press)
i have a lot more photos, but here are some teasers:
<img src="http://pictureposter.audiworld.com/54140/at050015.jpg">
<img src="http://pictureposter.audiworld.com/54140/at050043.jpg">
Lighting up the dark â€" improving road safety with intelligent lighting technology
AUDI AG
Stephan Berlitz, Head of Advance Development/Lighting
Technology Concepts
Manfred Hofbauer, Head of Headlight Development
Innovations in lighting technology always stem from the launching of new light sources. Halogen bulbs were followed by xenon headlights, then xenon lights in conjunction with pivoting headlights. These developments brought a steady improvement in road illumination for the driver. Audi adaptive light with pivoting xenon plus headlights is currently the most effective way of illuminating the road surface. Only Audi offers the additional feature that every car equipped with xenon plus headlights â€" whether fixed or pivoting â€" has separate integral daytime running lights. These bring additional safety by making sure that the car in question is always seen more easily by other road users. Pedestrians and oncoming vehicles can easily spot the car in daylight in all traffic situations, avoiding hazards as a result of it being overlooked. And the next leap in development is already waiting in the wings: LED headlights will open up yet more new horizons.
Yet lighting technology components are subject to strict specifications worldwide: ECE regulations in Europe and Japan, and FMVSS specifications in the USA. The development of a new lighting technology can only reach the market successfully if it is constantly checked against the international regulations. This explains the existence of committees that bring together vehicle and component manufacturers and representatives of government departments and research bodies. Drawing up standards nevertheless takes a very long time. Following its official release, Audi will make the new technology available as soon as possible and it already has potential applications up its sleeve.
Daytime running lights â€" bringing together safety and design
Starting with the twelve-cylinder Audi A8, the daytime running lights function has gradually been introduced in many models over the past year and a half.
Driving with the lights on during the daytime improves safety, as a car can then be seen much more easily by other road users, especially if it is of a subdued colour or if there is little contrast with its surroundings. In Scandinavian countries, all passenger cars are required by law to have daytime running lights; this is because twilight conditions are encountered much more commonly in those latitudes.
Research findings compiled by the SWOV Institute for Road Safety Research and the Dutch Institute for Road Safety (TNO Automotive) on behalf of the European Commission were published at the end of last year: new findings on the role of perception in accidents in conjunction with a renewed analysis of 24 older studies on the subject of daytime running lights indicated potential for avoiding up to 3,000 road deaths by the use of daytime running lights throughout Europe.
The background to this safety gain is the fact that vehicles are difficult to see even in daylight on shadowy roads or when camouflaged by their background, and are therefore spotted only very late or overlooked altogether. It is known from accident analyses that spotting other road users late or not at all accounts for 50 percent of daytime accidents, with the figure actually rising to 80 percent at junctions.
Based on the principle that lighting effects attract attention, vehicles equipped with daytime running lights are perceived more swiftly, identified as vehicles more easily (especially at the periphery of the field of vision) and their speed assessed more safely. Along with designed-in pedestrian protection measures in the forward structure, daytime running lights are thus verifiably one of the most effective protective measures. That explains why this issue is being promoted so forcefully by the VBG accident insurance association for clerical employees.
Daytime running lights are also already in use in Canada as well as in Scandinavia. Driving with the lights on during the daytime has also been officially recommended in Switzerland since the start of 2002. In Italy, it has been obligatory for two-wheeled vehicles and those using motorways to switch on the lights during the daytime since June 2002. In France, an official recommendation was made in autumn 2004 to drive with the lights on during the daytime on out-of-town roads.
Driving with dipped headlights is a rapid solution that is available to every driver. However, a large portion of the electrical energy is used for the unnecessary illuminating of the road, whereas only the diffused light above the light/dark boundary is used to enhance ease of identification for other road users. The law moreover requires the exterior lights, comprising the dipped headlights, sidelights, tail lights and licence plate light, to come on as a complete set. This results in high energy consumption, which in this instance is around 160 W, equivalent to an additional fuel consumption of around 0.2 litres per 100 kilometres. This is as unacceptable for reasons of operating cost as it is from an environmental viewpoint. The second major drawback of simply using the dipped headlights is the fact that conventional bulbs are not designed for this permanent load.
The SWOV / TNO study recommends separate daytime running lights as the best option, because these offer significant advantages compared with all other solutions particularly with regard to bulb operating life and added fuel consumption. At the end of 2004, this study met with an extremely positive reception from the highest-level traffic experts group of the European Parliament. Even the German representatives â€" who until then had been avowed opponents of daytime running lights â€" came out in favour of their mandatory fitting on new vehicles and retrofitting of the existing vehicle population.
Daytime running lights are realised in a particularly innovative way in the twelve-cylinder Audi A8: five white 1 Watt light-emitting diodes in a cloverleaf-pattern reflector generate the necessary light values from minimal energy input. The daytime running lights can be dimmed and therefore also double up as the sidelights. The pure white colour of the light underlines their exclusive appearance and harmonises perfectly with the light colour of the gas-discharge headlights.
In order to transfer the safety gain from daytime running lights to other car lines as well, starting with the new Audi A6 the auxiliary driving lights were replaced by daytime running lights. The daytime running lights are integrated into the xenon plus headlights in place of the auxiliary driving headlights (headlight flasher). This can be achieved because the xenon plus headlights generate the low beams and high beams from the same module. A super-long-life version of 21 W is used for the bulb for daytime running lights. In conjunction with dimming to 90 percent, the bulbs achieve operating lives that correspond to that of the vehicle itself. The energy balance of 38 W is very low, and the resulting extra fuel consumption of 0.05 litres per 100 kilometres only verifiable in theory. This solution has now been adopted in the Audi A4 and in all other A8 models. All further Audi model lines will gradually be given daytime running lights in the near future.
To give the customer the option of switching the daytime running lights off when driving in countries where they are not required by law, they can be deactivated: in the Audi A6 and A8 this is done via the MMI, and in the A4 and A3 car lines via a supplementary switch near the light switch.
Over and above the technical aspects already implemented, daytime running lights offer considerable scope for new departures in design. The minimum area of 40 cm2 called for by law for daytime running lights need not necessarily be of a round shape. Slender-design daytime running lights involving, for instance, the use of LEDs and optical fibres can involve solutions that enhance the vehicle's design and give it a distinctive outward appearance, whether as daytime running lights or as sidelights for driving at night time. This results in a genuine synthesis of safety and design.
Another solution is to combine two functions in a single reflector, for instance for the daytime running lights and high-beam headlights. This permits a very efficient use of space coupled with a dynamic design, with small-area lens apertures for the headlights.
Emergency braking lights
Whereas there is little need to identify the vehicle's tail end in daylight, an emergency braking situation cannot be signalled too clearly due to the impending risk of a rear-end collision. Emergency braking is signalled by the interplay of several sensors and control units.
The latest-generation standard-fit ESP identifies the emergency braking application and transmits a corresponding signal to the rear lights. In addition to the LED brake lights, the hazard warning lights are then activated. Drivers of vehicles following on behind automatically interpret the familiar signals of hazard warning flashers and brake lights as an "emergency stop". The function does not need to be explained or taught, and thus actively improves safety for following vehicles by alerting them early to the hazard situation.
There are several factors involved in the way the emergency braking situation is indicated. It should not be initiated too late, nor too early if the driver is merely driving in a sporty manner. The parameters to be evaluated are the rate of deceleration, the duration and intensity of braking, activation of brake assist, the location and number of any wheels locking, and of course the resumption of acceleration.
The calculation is performed in the latest-generation ESP control unit. The signals for the wheel sensors, brakes, yaw sensor etc. are processed accordingly. If emergency braking is identified, a signal is sent via a data bus and the rear lights are energised. This all takes place within a matter of milliseconds.
There are several ways in which the emergency brake application can be represented. The signal must be simple, to permit its swift, reliable recognition by following vehicles. It must moreover capture the attention and draw the eyes to the rear lights. A flashing signal has proved to be the most effective way of achieving this. Audi therefore combines familiar signals: flashing hazard warning lights as a familiar, clear indication of an unusual situation, in combination with the brake lights and the raised third brake light.
This signals that the brake has been applied. The vehicle behind is thus alerted early and swiftly to the hazard even if the driver is not constantly staring at the rear end of the vehicle in front. This is because the emergency braking information is transmitted for an appropriate period of time thanks to an integrated, variable after-run period. In normal braking situations, the vehicle always has a large brake light area available. Audi thus assures the same high standards of safety in everyday traffic even with the integral emergency brake lights.
The next development steps for such networked safety functions are already in the pipeline. LED headlights and intelligent rear lights, which are for instance networked with a light sensor, will represent the next innovation leaps.
Intelligent rear lights â€" adapted to the situation
As the next step in making the vehicle's tail end easier to spot after dark, Audi is working on intelligent rear lights. These will be able to adapt to the prevailing ambient light conditions.
The rear lights are the driver's means of communicating with the vehicles behind. The signals must therefore be clear and easy to see, without being distracting or even irritating. The rear lights are simultaneously an important design feature of the vehicle. This provides the framework for future technical concepts and their visual appeal.
Audi's aim is to render the rear fog light superfluous in the foreseeable future. In future it will be possible to automate this rear-end function, which is often forgotten or used incorrectly, with the aid of intelligent electronics. The brightness of such an adaptive rear light is modified in line with the prevailing ambient conditions, thus rendering the rear fog light superfluous. The light intensity is at its highest in fog or spray, and at its lowest when conditions after dark are clear. A rear light consisting of light-emitting diodes serves as the basis for this innovation.
The light intensity of the LEDs can easily be modified across a wide area by varying the power supply. Further conditions of their adoption in production are reliable ambient recognition and the use and interlinking of redundant signals.
Differentiation between daytime and night-time light levels is already permitted by law. The prevailing ambient brightness can be picked up by a light sensor and the light intensity of the tail, brake and turn indicator lights adapted. At night, a light intensity around one-third lower than at present is used, as the eyes adjust to the dark. During the day, the level is three times the present value to compensate for the higher ambient brightness caused by sunlight. This ensures that turn indicating or braking can be recognised even if the sun is shining directly on the rear lights.
A further area of development is technology integrated into the lights that senses dirt and the visibility range. Its purpose is to register ambient conditions such as fog, spray, rain and snow, detect whether the lenses are dirty and even measure the distance and speed of vehicles following on behind. This data is used to realise rear lights that adapt intelligently to the light intensity, checking the plausibility using the vehicle data from the light and rain sensor, steering angle sensor and speedometer signal.
In the event of contamination or poor visibility, the light level is increased; as vehicles behind get closer, the intensity of the fog light is reduced to the same level as the tail lights. The ambient data gathered can be made available to other safety systems via a data bus in the vehicle.
Variable light level control has already been submitted to the relevant European committees for type approval, and its statutory licensing is expected in 2007.
LED headlights â€" visible innovation
LED headlights use white high-performance light-emitting diodes instead of incandescent lamps or xenon lamps as their light source. LEDs occupy less space and can also be arranged with greater versatility, creating fresh scope for styling and front-end design.
Their main advantages are the very long operating life, high efficiency (their power consumption is half that of incandescent bulbs), a compact, sturdy shape, UV-free radiation, and low operating voltage.
The average operating life is twice that of the vehicle itself; it is no longer necessary to change bulbs, a process that therefore does not need to be taken into account when installing the lights. It is furthermore readily possible to vary the lighting current for situation-based applications.
The components for cooling are moved out of the visible range, to behind the light source. This, coupled with the lights' smaller visual appearance, means that much less installation depth is needed. The resulting considerable variability in height and depth creates scope for pedestrian protection concepts.
adaptive light (cornering light) could conceivably be offered as optional equipment in the form of additional LEDs that are electronically activated instead of mechanically pivoted.
Headlights with white light-emitting diodes (LEDs) as the light source have been used in many Audi concept vehicles as a result of their sharp rise in luminous power. Based on advance development concepts, the headlights of the Audi Pikes Peak study and the main headlights of the Audi Nuvolari quattro and Le Mans quattro took this topic as their basis. The current development status was installed in the Audi allroad quattro concept, in close coordination with Audi Design. The headlights are fully roadworthy, with dynamic beam range adjustment and integrated daytime running lights and indicator lights, and are already being put through countless tests and road trials in a prototype setup.
Particular attention is being paid to how the LEDs are cooled, as the chip's current temperature of 120 °C must in no circumstances be exceeded because this would cause it to fail. In development vehicles, cooling elements took the form of very large, highly ribbed aluminium components. This represents one of the major technical challenges, as the costs, the weight of the system and the efficiency are still unacceptable.
The space requirements are also very high, partly negating one of the main advantages of the LED headlight, namely its very flat design. A solid aluminium element in the vehicle's front end would in addition be a serious drawback in light of the new standards on pedestrian protection. It furthermore needs to be integrated stylistically and aesthetically in an appropriate way.
The use of small special fans was therefore tested in the Audi allroad quattro concept in parallel with the development version of the vehicle. These fans achieve the same cooling effect by means of forced convection, with a much smaller cooling element.
Lights such as the LED daytime running lights in the twelve-cylinder A8 are already ready for type approval. The headlights will probably receive SAE type approved from the end of 2005, and the corresponding ECE type approval is expected from the end of 2007. The predicted light output of LEDs will then permit their technical realisation. LEDs will probably be able to match the light output of xenon headlights from 2008. In the long term, LED headlights are forecast to outstrip the market share of xenon headlights.
The hardware and software systems integration of lighting functions will have a decisive effect on competition. The first vehicle manufacturer to establish processes in which lighting engineers are brought together with systems architects will secure itself a major advantage. This will ultimately involve replacing electromechanical systems with software. For lighting technology, however, aesthetic appeal is more important than all technical innovations. Without an exclusive, evocative and attractive design, LED technology will not be able to dominate the market.
<img src="http://pictureposter.audiworld.com/54140/at050015.jpg">
<img src="http://pictureposter.audiworld.com/54140/at050043.jpg">
Lighting up the dark â€" improving road safety with intelligent lighting technology
AUDI AG
Stephan Berlitz, Head of Advance Development/Lighting
Technology Concepts
Manfred Hofbauer, Head of Headlight Development
Innovations in lighting technology always stem from the launching of new light sources. Halogen bulbs were followed by xenon headlights, then xenon lights in conjunction with pivoting headlights. These developments brought a steady improvement in road illumination for the driver. Audi adaptive light with pivoting xenon plus headlights is currently the most effective way of illuminating the road surface. Only Audi offers the additional feature that every car equipped with xenon plus headlights â€" whether fixed or pivoting â€" has separate integral daytime running lights. These bring additional safety by making sure that the car in question is always seen more easily by other road users. Pedestrians and oncoming vehicles can easily spot the car in daylight in all traffic situations, avoiding hazards as a result of it being overlooked. And the next leap in development is already waiting in the wings: LED headlights will open up yet more new horizons.
Yet lighting technology components are subject to strict specifications worldwide: ECE regulations in Europe and Japan, and FMVSS specifications in the USA. The development of a new lighting technology can only reach the market successfully if it is constantly checked against the international regulations. This explains the existence of committees that bring together vehicle and component manufacturers and representatives of government departments and research bodies. Drawing up standards nevertheless takes a very long time. Following its official release, Audi will make the new technology available as soon as possible and it already has potential applications up its sleeve.
Daytime running lights â€" bringing together safety and design
Starting with the twelve-cylinder Audi A8, the daytime running lights function has gradually been introduced in many models over the past year and a half.
Driving with the lights on during the daytime improves safety, as a car can then be seen much more easily by other road users, especially if it is of a subdued colour or if there is little contrast with its surroundings. In Scandinavian countries, all passenger cars are required by law to have daytime running lights; this is because twilight conditions are encountered much more commonly in those latitudes.
Research findings compiled by the SWOV Institute for Road Safety Research and the Dutch Institute for Road Safety (TNO Automotive) on behalf of the European Commission were published at the end of last year: new findings on the role of perception in accidents in conjunction with a renewed analysis of 24 older studies on the subject of daytime running lights indicated potential for avoiding up to 3,000 road deaths by the use of daytime running lights throughout Europe.
The background to this safety gain is the fact that vehicles are difficult to see even in daylight on shadowy roads or when camouflaged by their background, and are therefore spotted only very late or overlooked altogether. It is known from accident analyses that spotting other road users late or not at all accounts for 50 percent of daytime accidents, with the figure actually rising to 80 percent at junctions.
Based on the principle that lighting effects attract attention, vehicles equipped with daytime running lights are perceived more swiftly, identified as vehicles more easily (especially at the periphery of the field of vision) and their speed assessed more safely. Along with designed-in pedestrian protection measures in the forward structure, daytime running lights are thus verifiably one of the most effective protective measures. That explains why this issue is being promoted so forcefully by the VBG accident insurance association for clerical employees.
Daytime running lights are also already in use in Canada as well as in Scandinavia. Driving with the lights on during the daytime has also been officially recommended in Switzerland since the start of 2002. In Italy, it has been obligatory for two-wheeled vehicles and those using motorways to switch on the lights during the daytime since June 2002. In France, an official recommendation was made in autumn 2004 to drive with the lights on during the daytime on out-of-town roads.
Driving with dipped headlights is a rapid solution that is available to every driver. However, a large portion of the electrical energy is used for the unnecessary illuminating of the road, whereas only the diffused light above the light/dark boundary is used to enhance ease of identification for other road users. The law moreover requires the exterior lights, comprising the dipped headlights, sidelights, tail lights and licence plate light, to come on as a complete set. This results in high energy consumption, which in this instance is around 160 W, equivalent to an additional fuel consumption of around 0.2 litres per 100 kilometres. This is as unacceptable for reasons of operating cost as it is from an environmental viewpoint. The second major drawback of simply using the dipped headlights is the fact that conventional bulbs are not designed for this permanent load.
The SWOV / TNO study recommends separate daytime running lights as the best option, because these offer significant advantages compared with all other solutions particularly with regard to bulb operating life and added fuel consumption. At the end of 2004, this study met with an extremely positive reception from the highest-level traffic experts group of the European Parliament. Even the German representatives â€" who until then had been avowed opponents of daytime running lights â€" came out in favour of their mandatory fitting on new vehicles and retrofitting of the existing vehicle population.
Daytime running lights are realised in a particularly innovative way in the twelve-cylinder Audi A8: five white 1 Watt light-emitting diodes in a cloverleaf-pattern reflector generate the necessary light values from minimal energy input. The daytime running lights can be dimmed and therefore also double up as the sidelights. The pure white colour of the light underlines their exclusive appearance and harmonises perfectly with the light colour of the gas-discharge headlights.
In order to transfer the safety gain from daytime running lights to other car lines as well, starting with the new Audi A6 the auxiliary driving lights were replaced by daytime running lights. The daytime running lights are integrated into the xenon plus headlights in place of the auxiliary driving headlights (headlight flasher). This can be achieved because the xenon plus headlights generate the low beams and high beams from the same module. A super-long-life version of 21 W is used for the bulb for daytime running lights. In conjunction with dimming to 90 percent, the bulbs achieve operating lives that correspond to that of the vehicle itself. The energy balance of 38 W is very low, and the resulting extra fuel consumption of 0.05 litres per 100 kilometres only verifiable in theory. This solution has now been adopted in the Audi A4 and in all other A8 models. All further Audi model lines will gradually be given daytime running lights in the near future.
To give the customer the option of switching the daytime running lights off when driving in countries where they are not required by law, they can be deactivated: in the Audi A6 and A8 this is done via the MMI, and in the A4 and A3 car lines via a supplementary switch near the light switch.
Over and above the technical aspects already implemented, daytime running lights offer considerable scope for new departures in design. The minimum area of 40 cm2 called for by law for daytime running lights need not necessarily be of a round shape. Slender-design daytime running lights involving, for instance, the use of LEDs and optical fibres can involve solutions that enhance the vehicle's design and give it a distinctive outward appearance, whether as daytime running lights or as sidelights for driving at night time. This results in a genuine synthesis of safety and design.
Another solution is to combine two functions in a single reflector, for instance for the daytime running lights and high-beam headlights. This permits a very efficient use of space coupled with a dynamic design, with small-area lens apertures for the headlights.
Emergency braking lights
Whereas there is little need to identify the vehicle's tail end in daylight, an emergency braking situation cannot be signalled too clearly due to the impending risk of a rear-end collision. Emergency braking is signalled by the interplay of several sensors and control units.
The latest-generation standard-fit ESP identifies the emergency braking application and transmits a corresponding signal to the rear lights. In addition to the LED brake lights, the hazard warning lights are then activated. Drivers of vehicles following on behind automatically interpret the familiar signals of hazard warning flashers and brake lights as an "emergency stop". The function does not need to be explained or taught, and thus actively improves safety for following vehicles by alerting them early to the hazard situation.
There are several factors involved in the way the emergency braking situation is indicated. It should not be initiated too late, nor too early if the driver is merely driving in a sporty manner. The parameters to be evaluated are the rate of deceleration, the duration and intensity of braking, activation of brake assist, the location and number of any wheels locking, and of course the resumption of acceleration.
The calculation is performed in the latest-generation ESP control unit. The signals for the wheel sensors, brakes, yaw sensor etc. are processed accordingly. If emergency braking is identified, a signal is sent via a data bus and the rear lights are energised. This all takes place within a matter of milliseconds.
There are several ways in which the emergency brake application can be represented. The signal must be simple, to permit its swift, reliable recognition by following vehicles. It must moreover capture the attention and draw the eyes to the rear lights. A flashing signal has proved to be the most effective way of achieving this. Audi therefore combines familiar signals: flashing hazard warning lights as a familiar, clear indication of an unusual situation, in combination with the brake lights and the raised third brake light.
This signals that the brake has been applied. The vehicle behind is thus alerted early and swiftly to the hazard even if the driver is not constantly staring at the rear end of the vehicle in front. This is because the emergency braking information is transmitted for an appropriate period of time thanks to an integrated, variable after-run period. In normal braking situations, the vehicle always has a large brake light area available. Audi thus assures the same high standards of safety in everyday traffic even with the integral emergency brake lights.
The next development steps for such networked safety functions are already in the pipeline. LED headlights and intelligent rear lights, which are for instance networked with a light sensor, will represent the next innovation leaps.
Intelligent rear lights â€" adapted to the situation
As the next step in making the vehicle's tail end easier to spot after dark, Audi is working on intelligent rear lights. These will be able to adapt to the prevailing ambient light conditions.
The rear lights are the driver's means of communicating with the vehicles behind. The signals must therefore be clear and easy to see, without being distracting or even irritating. The rear lights are simultaneously an important design feature of the vehicle. This provides the framework for future technical concepts and their visual appeal.
Audi's aim is to render the rear fog light superfluous in the foreseeable future. In future it will be possible to automate this rear-end function, which is often forgotten or used incorrectly, with the aid of intelligent electronics. The brightness of such an adaptive rear light is modified in line with the prevailing ambient conditions, thus rendering the rear fog light superfluous. The light intensity is at its highest in fog or spray, and at its lowest when conditions after dark are clear. A rear light consisting of light-emitting diodes serves as the basis for this innovation.
The light intensity of the LEDs can easily be modified across a wide area by varying the power supply. Further conditions of their adoption in production are reliable ambient recognition and the use and interlinking of redundant signals.
Differentiation between daytime and night-time light levels is already permitted by law. The prevailing ambient brightness can be picked up by a light sensor and the light intensity of the tail, brake and turn indicator lights adapted. At night, a light intensity around one-third lower than at present is used, as the eyes adjust to the dark. During the day, the level is three times the present value to compensate for the higher ambient brightness caused by sunlight. This ensures that turn indicating or braking can be recognised even if the sun is shining directly on the rear lights.
A further area of development is technology integrated into the lights that senses dirt and the visibility range. Its purpose is to register ambient conditions such as fog, spray, rain and snow, detect whether the lenses are dirty and even measure the distance and speed of vehicles following on behind. This data is used to realise rear lights that adapt intelligently to the light intensity, checking the plausibility using the vehicle data from the light and rain sensor, steering angle sensor and speedometer signal.
In the event of contamination or poor visibility, the light level is increased; as vehicles behind get closer, the intensity of the fog light is reduced to the same level as the tail lights. The ambient data gathered can be made available to other safety systems via a data bus in the vehicle.
Variable light level control has already been submitted to the relevant European committees for type approval, and its statutory licensing is expected in 2007.
LED headlights â€" visible innovation
LED headlights use white high-performance light-emitting diodes instead of incandescent lamps or xenon lamps as their light source. LEDs occupy less space and can also be arranged with greater versatility, creating fresh scope for styling and front-end design.
Their main advantages are the very long operating life, high efficiency (their power consumption is half that of incandescent bulbs), a compact, sturdy shape, UV-free radiation, and low operating voltage.
The average operating life is twice that of the vehicle itself; it is no longer necessary to change bulbs, a process that therefore does not need to be taken into account when installing the lights. It is furthermore readily possible to vary the lighting current for situation-based applications.
The components for cooling are moved out of the visible range, to behind the light source. This, coupled with the lights' smaller visual appearance, means that much less installation depth is needed. The resulting considerable variability in height and depth creates scope for pedestrian protection concepts.
adaptive light (cornering light) could conceivably be offered as optional equipment in the form of additional LEDs that are electronically activated instead of mechanically pivoted.
Headlights with white light-emitting diodes (LEDs) as the light source have been used in many Audi concept vehicles as a result of their sharp rise in luminous power. Based on advance development concepts, the headlights of the Audi Pikes Peak study and the main headlights of the Audi Nuvolari quattro and Le Mans quattro took this topic as their basis. The current development status was installed in the Audi allroad quattro concept, in close coordination with Audi Design. The headlights are fully roadworthy, with dynamic beam range adjustment and integrated daytime running lights and indicator lights, and are already being put through countless tests and road trials in a prototype setup.
Particular attention is being paid to how the LEDs are cooled, as the chip's current temperature of 120 °C must in no circumstances be exceeded because this would cause it to fail. In development vehicles, cooling elements took the form of very large, highly ribbed aluminium components. This represents one of the major technical challenges, as the costs, the weight of the system and the efficiency are still unacceptable.
The space requirements are also very high, partly negating one of the main advantages of the LED headlight, namely its very flat design. A solid aluminium element in the vehicle's front end would in addition be a serious drawback in light of the new standards on pedestrian protection. It furthermore needs to be integrated stylistically and aesthetically in an appropriate way.
The use of small special fans was therefore tested in the Audi allroad quattro concept in parallel with the development version of the vehicle. These fans achieve the same cooling effect by means of forced convection, with a much smaller cooling element.
Lights such as the LED daytime running lights in the twelve-cylinder A8 are already ready for type approval. The headlights will probably receive SAE type approved from the end of 2005, and the corresponding ECE type approval is expected from the end of 2007. The predicted light output of LEDs will then permit their technical realisation. LEDs will probably be able to match the light output of xenon headlights from 2008. In the long term, LED headlights are forecast to outstrip the market share of xenon headlights.
The hardware and software systems integration of lighting functions will have a decisive effect on competition. The first vehicle manufacturer to establish processes in which lighting engineers are brought together with systems architects will secure itself a major advantage. This will ultimately involve replacing electromechanical systems with software. For lighting technology, however, aesthetic appeal is more important than all technical innovations. Without an exclusive, evocative and attractive design, LED technology will not be able to dominate the market.
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