Automotive Engineer

LED lighting technology is becoming more widespread as OEMs look to improve light quality and functionality.

Compared to xenon technology, which offers a colour temperature of 3,000K, LEDs can provide 5,500K, giving better visibility to drivers. But the technology also allows OEMs to offer functionality that can improve driver comfort and safety. Adaptive headlighting, linked to the vehicle’s navigation system, can control beam range and placement, depending on road types.

The technology has been used primarily in performance vehicles such as the Audi R8 sportscar, but is moving to more mainstream vehicle segments.

LEDs are simply semiconductors which generate light by electron flow within the gap width of the semiconductor. Although expensive compared to more traditional light sources, LEDs offer good durability and also reduce energy consumption. 

Tier One suppliers such as Hella, which developed the technology for the Audi R8, are having to meet increasing demand from OEMs for LED headlights.

The R8’s headlamps integrate an adaptive front lighting system that includes functionality such as motorway and adverse weather lighting – adapting the headlights to the driving situation. Additionally a tourist light is integrated, which can switch the light distribution according to GPS data, so the headlights change for use in either right- or left-hand drive countries.

High-precision tooling and manufacturing methods are necessary to ensure the relative position of the light distribution. On the Audi R8, low beam is generated with four different light patterns: far field with 15° cut off, far field with horizontal cut off, basis range and broad field illumination.

As OEMs look more closely at ways to make vehicles more efficient, the number of vehicles that use LEDs will grow. More functionality will be integrated, including vertical cut-off lines to generate a glare-free high beam without blinding oncoming drivers. And the cost of the technology will fall as OEMs and Tier Ones benefit from economies of scale.

1.Cornering light LED module
The cornering light LED module consists of a four-chip LED and is activated during tight cornering manoeuvres, during activation of the direction indicator below 40km/h and as part of the adverse weather light function to improve side road illumination.

2.Daytime running light, position light, direction indicator integratedLED module
Consisting of 44 light optics, divided into 22 white LEDs and 22 yellow LEDs. The white LEDs are dimmed to position thelight. Heat sinks are attached by a carrying frame with plastic springs.

3. Lowbeam cover and LED modules
Ten plastic lenses are used for low beam, which include far field, basis and broad field illumination. The low-beam function usesfour one-chip LEDs and six two-chip LEDs. The far field is an indirect projection module with a shutter while field modules are direct projection systems.

4.High beam/motorway LED module
Two four-chip LEDs are used for the reflector high-beam light function, and one four-chip LED is used for the motorway function which is activated above 110km/h and linked to the GPS navigation system.

5.Low beam-carrier frame and cover frame
The component includes a horizontal adjustment of the cut-off line. Both parts are made from high-precision plastic.

6.Low and high beam harness
The high-power converter drives all lighting functions and adapts the electrical current flow to meet the maximum allowed temperature of the LEDs and the LED light class coding.

7.LED module carrier frame
Supports all LED modules in the headlight. It allows the vertical adjustment of all light functions according to the chassis of the vehicle. An exchangeable fan is mounted which guides air flow to the heat sinks of all the LED modules, generating a constant air flow within the headlamp for cooling.