Focus: Interior Lighting

Infiniti QX Inspiration, blue underlighting in the Volkswagen ID.3, OLEDs shine through high-pressure water-cut perforations in the leather of the door cards in the Cupra Tavascan

Looking beyond the lounge

The end of the age of speed is having a profound effect on the way car designers are thinking about interiors, and especially their lighting. Previously, focus was on the driver: the switchgear and cockpit were angled and lit to ensure very little got in the way of single-minded concentration on the road ahead.

“Before, you wanted to go as fast as possible, like a jet fighter,” Klaus Bischoff, head of design, Volkswagen, told Interior Motives at the Frankfurt auto show, where he was unveiling the compact, electric ID.3. “Now it starts to be more relaxed. The car is taking on more responsibility so that after a stressful day, this is your private room. We want to give the people the feeling you’re home. Lighting is one way we play with that.”

Semi-autonomous technology allows for a smidgeon less concentration at the wheel, and electric motors replace engine noise, thus bringing the focus into the cabin. The car-as-living-room analogy is incomplete, however; rather than just a space to relax, the car of the future needs to adapt to the mood we’re in. Depending on the level of autonomy, the car will be called on to act as office, bedroom, lounge, or even kitchen. It needs to wake us up in the morning, relax us in the evening, keep us alert, reconnect us with the outside world – and generally help us stay sane. To do all this, lighting will have to play a key role.

The basic light technology to achieve this is already here: the RGB (red, green, blue) LED. “The light source is relatively easy, it’s what comes after that are the innovative parts,” says Ana Bizal, head of lighting innovation pre-development and development of lighting technology, Hella. “You’ve millions of colours, different intensity levels, different materials – [but] how to bring this into a story line to add value, this is the point.”

Faurecia-Hella demonstrator, ambient lighting in the BMW 7 Series, by Webasto Group, Hella’s reading lamps in the Audi A8

Premium positioning

Light is “one part that creates the next premium,” said Marc Lichte, head of design, Audi, in Frankfurt. “In the past, it was leather and chrome, and that’s what we thought of as premium luxury. In the future, it’s something different: it’s about the materials, about the fabrics, and also about how to use the light to create a different atmosphere. It’s about wellbeing.”

The ability to alter where the light is coming from is key to changing that atmosphere. “For the office feeling you need to have overhead lighting – cold, very focused,” says Ana Bizal. “For the living room, you don’t want a headlamp in your face, but maybe you want the light to come as if from nowhere.”

Hella was responsible for the overhead lights giving seven different reading zones in the current Audi A8, but Bizal says that’s just the start. Light positioning is also key to flattering a car’s occupants, she adds. “Nobody looks good with overhead lighting – you need to have light spread vertically, so that you look pretty,” she says. “It’s the difference between looking like a zombie or [the model] Heidi Klum.”

To illustrate its thinking on interior lights, Hella teamed up with Faurecia to create a show car – based on a Renault Espace – that demonstrates a possible future for lighting and materials. In this concept, first displayed at the 2018 Paris motor show, the cabin tone is set by a diffused overhead light that shines as though it is coming from the length and breadth of a panoramic sunroof. This is achieved by placing hidden LED strips along the sides that light up the fabric, spreading the light through the cabin. The car is said to be semi-autonomous, with a steering wheel that retracts when it reaches an autonomous zone such as a motorway. At the same time, hidden lights from the roof, from the footwell, and from inside slim door pockets change colour to more relaxing, warmer tones. The lights in the footwells even flicker, suggesting a fireplace.

Fibre optics for Karma

For Karma Automotive, its first in-house concept car was an opportunity to showcase innovative 3D printing and lighting techniques. The Karma SC-1, a sleek two-seat roadster, was designed to reflect the California spirit in which it was conceived; stepping in, one immediately notices the ambient lighting, made up from LEDs and diffusers and found in the armrest cavities in the doors and in the recess areas around the seats. A second look then reveals more subtle lighting that invites a closer inspection. LED lights run along the key lines in the cockpit and are also employed to balance the positive and negative spaces in the cabin.

Andre Franco Luis, director of interior design at Karma, explains: “The LED lights are made of individual strands of 0.5mm Versalume fibre optics. This allows not only thin strips of lights, but also a remarkable integration of interior surfacing and lighting.”

Panels of 3D printed materials are crafted according to the ergonomic needs of the passengers in a particular area. These areas appear ‘quilted’ with diamond and chevron patterns. LED strands are integrated to varying degrees with these patterns, allowing for a jewel-like quality to the interior surfaces, or a new kind of quilted material with threads of light woven into interior surfaces.

Karl Smith

Hyundai 45 concept, with diffused natural light from a slatted louvre-blind effect, and a band of lighting running around the cabin, Kia Telluride concept’s overhead ‘light therapy’ console

Wellness and wellbeing

The idea of light as a function of wellbeing is being explored by car designers, mirroring airlines’ experimentation with light therapy to reduce the effects of jet lag. Kia’s Telluride SUV concept (2016) included a large wing-shaped LED panel on the roof facing the passengers, said to reduce jet lag; this connected to smart sensors in the seat, meant to detect fluctuations in the occupants’ wellbeing. Hyundai similarly played with this idea of light’s healing properties for the 45 coupé concept shown at Frankfurt this year.

The idea behind the 45’s interior was to recreate that living room feeling, partly by using light. “A lot of new automotive interiors are getting cluttered with technology, with glass and metal, and can look cold and artificial and industrial. We wanted to retain this feeling we call natural warmth,” says Hak Soo Ha, Hyundai’s interior design director. “A lot of car companies started out having accent lighting, but I think we can take it a lot further.”

The natural element in the 45 comes from materials such as bamboo fibre and wool, but also from daylight. Hyundai subtly played with this by using slats across the glass roof to reduce the glare and produce patterns across the seating, a little like the effect from louvre blinds in a living room on a sunny day. The other key lighting effect is produced by a continuous band of light running around the car at door-pocket height, amplified by a strip of clear bio-resin. The strip blends two tones, one at the front of the car, another to the rear, to produce different moods as a kind of light therapy. “It taps into your subconscious and conscious sides of the brain, and monitors feelings and emotions and biorhythms,” says Soo Ha.

Rather than using seat monitors as in the Telluride, the 45 is said to monitor the drivers’ social-media status updates to discover their mood, and then change the lighting accordingly. Light intensity is another tool: if your commute is completely in the dark in winter, for example, the 45 would create its own sunrise by gradually brightening the interior lights. “Even if you never see the sun on that day, you can start your biorhythm by artificially – but very naturally – intensifying the lightness,” says Soo Ha.

Hiding the tech

Another feature of the 45 which is becoming more popular is using light to identify buttons that would otherwise be hidden behind the dashboard fabrics, a feature Hak Soo Ha calls “fully manufacturable”. The idea [above] is to create simplicity and not overwhelm the driver, and is becoming more common as lighting and materials suppliers team up, much as Hella and Faurecia have done. “No one can do it alone,” says Hella’s Ana Bizal, citing the need to get the material surface texture exactly right to allow the light effects to function properly.

The technology to do this is being enabled by touch sensors made by the likes of Germany’s Kurz Group, which integrates them with lights [below] and enables not just on/off ability but also more graduated control such as volume; and by Yanfeng Technology, which has even developed a slider-style touch-sensitive light graphic. The ability to make such buttons disappear gives designers more freedom: for example, the Bentley EXP 100 GT concept [see p06] features seat control switches that follow the seat as it moves forward, i.e. when switching into driver mode after a spell of autonomous control.

The ‘disguise material’ to achieve this is becoming sought after as manufacturers seek to evolve in their shift to offering more high-tech electric cars. “One reference is the Model 3 from Tesla, which has a clean intuitive dashboard with fewer buttons and knobs,” says Mike Godwin, director of automotive LED marketing, Osram. Not everyone likes the single-screen approach however, making disguised buttons appealing, both for keeping a design clean and for retaining traditional switchgear.

European carmakers are further ahead than the Americans with this technology, Godwin believes, but there’s work to be done before widespread adoption can be achieved. “I think it will comes to production but it needs a haptic feedback, a feeling of touching the surface that isn’t there, and that’s a whole other gamut of things that need to evolve,” he says.

Playful, precise – or purifying

Cleanliness of on-demand ride-share vehicles is a significant user concern, and the Yanfeng XiM20 demonstrator vehicle [IM: Spring 2019] showcases the application of UV light to sanitise air and surfaces in a cabin, said to kill up to 99.9% of bacteria on directly-targeted surfaces. Yanfeng’s antimicrobial Wellness Pod leverages technologies already used in medical environments and can be mounted as an overhead console or concealed within the interior; it vents UV-C light for air sanitisation (of bacteria and viruses) and sweeps blue light over the surfaces in a 30-minute process during downtime. This can be monitored and controlled via a smartphone app, and combined with scent diffusion.

Lighting is applied for an interactive ambient effect in the snug rear section of the XiM20’s cabin, where adaptive low-resolution multi-coloured patterns can be gesture-controlled and customised using sensor technology from partner firm IEE. An infrared stereo camera captures movement in the cabin, data is fed to Yanfeng’s smart cabin controller, and light is projected accordingly from the textile headliner. “It’s reading the whole space,” explains Tim Shih, VP of design and user experience, Yanfeng Technology. “It can see where you’re looking, and with time, it can develop an algorithm, reading the whole volume and reacting accordingly. The gesture controls are like drawing on the surface, drawing with light, or you can project [an image of] the scenery outside, the environment you’re in.”

“The car can recognise mood and status and match the ambient lighting effect,” adds Dr. Yanning Zhao, engineering manager for product innovation, based at Yanfeng’s European R&D centre in Neuss, Germany. “As well, you can use the ‘activeSkin’ [underlit textiles] as a display for abstract information – not HD content, but sufficient for abstract information. This reduces cognitive load, gives a soft feeling, and can help keep kids in the rear seats occupied. There are some functions such as simple games; you don’t want big displays shouting at you, but it is a normal display surface.”

More precise, higher-resolution underlighting is then seen embedded in the smart surfaces such as the wood of the XiM20’s large table-style IP, which replaces conventional black screens to communicate information and incorporate touch-sensitive controls. This “secret OLED effect” also reduces cognitive load, Zhao explains, and “the combination of lighting effects and switching functions, backlit icons and capacitive touch combined, is dynamic. They [the icons] can be different colours, and there is haptic feedback which gives the feeling of a switch or button.”

For production vehicle applications, surfaces including real or artificial leather can be underlit in areas such as door cards, icons only illuminating when they are needed, i.e. when a hand comes close to adjust seating or to switch driving modes, or to give alerts, such as blind spot warning or warning that it is not safe to open a door. “You can change the sharpness of the display icons and illumination, for a soft light effect,” says Zhao, “and combine other soft surfaces and different translucent materials. It’s a very scalable technology, and you can manipulate the translucency. The challenge is that in an interior, you have a lot of dark surfaces where optic transmission is very low, so light translucency is very low. We can get lighter icons depending on the use case, and are continuing discussions on applications for brightness, i.e. higher luminescence for switching functions than for ambient – which can also save on the cost of LEDs.” She further points to a simulated sliding switch with graded colours, well-suited to functions such as audio controls.

For purely decorative effect, Yanfeng has been developing backlit layered glass surfaces [pictured below] with patented anti-chip foiling and a laminated safety layer like that of windshields, which could be used on the IP, doors or centre console. “We can go to multiple layers,” says Radisa Göritz, engineering manager, product innovation. “We can have inserts of metal, wood, stone; [embedded] fabrics or screen-printing can add decorative aspects; and sandblasting on the surface for 3D effects. We can do edge lighting, or embed clusters of LEDs into the glass or its background, have warning lights under the glass, and add capacitive touch, mechanical buttons and displays. There is high potential to contain all this in the glass, and it is absolutely mass production-designed.”

Farah Alkhalisi

Meet the micro-LED

The SmartVIZ project is exploring the application of micro-LEDs (µLEDs) said to be brighter, more robust and more efficient than current OLED technology. Osram Opto Semiconductors is working with Fraunhofer IISB (Institute for Integrated Systems and Device Technology, Erlangen, Germany) and ASM AMICRA Microtechnologies of Regensburg on high-resolution transparent visualisation of imagery for automotive interiors. SmartVIZ, funded by the Bavarian state, began in November 2018 and intends to present a demonstrator prototype in November 2021. “Since µLED technology can produce extremely high luminance in a wide dynamic range, it can play a key role for future mega-trends such as augmented reality applications,” Osram said in a statement.

The first phase of the project will look at designing efficient µLED light sources; it will then look at their handling on a sub-component level; and then move to final assembly. It will create red, green and blue µLED structures which act as high-luminance image micro-pixels, said to require “in-depth studies of the underlying principles that are in part entirely different to today’s macro LED chips.” It will also research transparent substrates for thin-film transistors (TFTs) to give ultra high-resolution surfaces that will only be filled with content when the µLEDs are active.

Projections in the Volkswagen ID.3, Jaguar Land Rover’s next-generation 3D AR HUD, VR concept from Luxoft

Dynamic guidance

Semiconductors, as supplied by firms such as Osram, are needed to make control of lights smarter, either singly or in groups: useful when making lights more dynamic, whether for providing a more emotional experience or to help give information.

Volkswagen’s ID.3 demonstrates how light can simply, yet usefully, inform the driver without relying on screens. A strip of light positioned right below the windscreen delivers dynamic instruction such informing the driver when it’s safe to change lane, indicating when to brake, and when to move lanes to follow the navigation route. This is part of a lighting system VW calls ID.light, and it represents a step up from simple light-based warnings such as blind-spot indication lights on the wing mirrors. Once cars are able to operate autonomously in certain zones, ways are needed to alert the driver that the zone is ending, and that they need to be alert enough to take over; intelligent lighting such as ID.light will be adapted to achieve this.

This is a production interpretation of the projections and display concept seen in the ID Concept [IM: Autumn 2016] and reflects the growing use and influence of AR and VR – a strong theme at CES 2019 from suppliers such as Luxoft [concept pictured, right], and under development at Jaguar Land Rover, which is working with the the Centre for Advanced Photonics and Electronics (CAPE) at the University of Cambridge on an immersive 3D head-up display that could, in a future autonomous vehicle, stream movies as well.

Physical projection

Hak Soo Ha at Hyundai pictures another use of light: to project a dot somewhere around the beltline, to indicate which way is home just after you get into the car. He says it would give drivers reassurance in a disorienting location, and give a physical focus that the sat nav can’t offer.

Projecting light to give information is another trend we’re seeing more of – for example, the Hella/Faurecia Espace uses a roof-mounted projector to display a welcome message on the seats. This is similarly seen in some shared-car concepts; the Audi AI:ME [IM: Summer 2019] greets its passengers, for example [right], and the Yanfeng XiM20 [IM: Spring 2019] has a ‘bulletin board’ illuminated interior panel [above, right].

Another car using projection is the Mercedes-Benz Vision EQS concept [left and above] seen at the Frankfurt show: this envisages using projection rather than backlit materials to display temporary ‘buttons’ on the dashboard. The Vision EQS in fact showcases much of the technology mentioned on previous pages; for example, a ‘light belt’ surrounding the entire cabin changes colour according to mood, and can also be used as a dynamic information communicator. It also features buttons within the trim to change the lighting mood, or open or close the windows.

Interior light therefore is heading far beyond its long-held role of illuminating the interior and dials. Even when invisible, it can play a part via gesture control. Whether it really can improve our mood on a dark wet commute home remains to be seen, but as relaxation becomes a new battleground, especially among the premium automakers, the humble LED is certainly working harder than it has ever done before.