ST and Audi to Develop OLED Brake Lights

Customisable vehicle exterior lighting might display animations or warning signs

ST and Audi have announced a joint project to develop organic light emitting diode (OLED) technology for vehicle exterior lights.

The project aims to develop OLED lighting that will allow lighting patterns to be customised and animated, by controlling hundreds of OLEDs at a time. This will complement Audi’s styling for future vehicles but should improve safety, too – imagine vehicles warning other drivers of hazards in the road ahead such as stationary traffic or localised ice.  

ST and Audi are working together on a project to develop OLED systems for automotive exterior lighting (Image: ST Microelectronics)

Audi has been using OLED in its vehicles since 2016 when it used the technology in the rear lights of the Audi TT RS. OLEDs are particularly attractive since they have a flat light source, making the lighting effect much more homogenous than for point sources like LEDs. OLEDs feature continuous dimming, that is, they can be dimmed to any brightness level. They are suitable for use in vehicle exterior lighting since they don’t cast shadows and don’t require any optical components like light guides or reflectors. Further, OLEDs exhibit excellent contrast and very small gaps between segments. The OLEDs’ stack of cathode, emissive layer and transparent anode can be as thin as 1mm.

Customizing lieghting design and to be used for Car-to X-communication

The first demonstration of the results from the joint project came at the International Symposium on Automotive Lighting (ISAL) in Darmstadt, Germany at the end of September. Audi unveiled a new digital OLED technology at the show.

While previous generations of Audi’s OLED technology featured four segments, the new version has more than 50 segments. This, combined with OLEDs’ continuous dimmability, means the same hardware can produce a variety of lighting designs.

The new Audi technology features more than 50 OLED segments for automotive rear lighting (Image: Audi AG)

As part of Audi’s ISAL demo, ST built a control system for the OLEDs which allowed the brightness of individual pixels to be continuously adjusted. It used a high-speed communication layer embedded in the actuator IC that was specifically developed by ST for lighting applications.

ST has been a member of Audi’s Progressive Semiconductor Program (PSCP) since 2012, with the partnership initially focusing on emissions, safety, security, infotainment and comfort.

Sally Ward-Foxton is a Correspondent for EETimes and EETimes Europe