The Psychology of Automotive LED Lighting

By Carolyn Mathas

When we think of automotive lighting, our first thoughts often go to high-performance headlamps, bold taillights, and running lights that create strong branding statements. While these trends continue, LEDs are also used as general ambient lighting. What started out as an indicator light application has given way to slick-looking backlit displays, practical-minded occupancy detection and all manner of ambient lighting based on attempts to affect occupant mood, the time of day, and other environmental factors.

Here, ambient lighting refers less to instrument panel lighting than to the indirect interior illumination that gives the driver a sense of orientation and spaciousness as well as feelings of safety, comfort, and even a sense of pride in value. Ambient lighting delivers an emotional atmosphere and, according to carmakers, ties together exterior and interior lighting conditions for the driver for decreased levels of driving fatigue.

Ambient lighting is now incorporated into innovative turn- and brake-lighting applications, backlit displays, occupancy detection, night vision, and more. Lighting can actually make us feel differently about our driving and ourselves. Ambient lighting makes a statement as well as an impact on the driving experience.

Figure 1: Ambient lighting is now incorporated into innovative turn- and brake-lighting applications, backlit displays, occupancy detection, night vision, and more.

The Psychology of Color and Light

People are used to evaluating the color of light in home and office. There is a real impact and psychological effect of warm or cool lighting in our environment that relates to eye fatigue, wakefulness, circadian rhythms and mood. For example, yellow light is seen as warm and pleasant, while bright white light is seen as clean and efficient. Automakers have determined that color and lighting can go much deeper than a mere visual impression.

A variety of emotions can be encouraged with certain hues. BMW engineers and the Lighting Engineering Group at Ilmenau University of Technology in Munich conducted a benchmark study on automotive interior lighting in 2009. The study involved a series of questions answered by participants after driving a real but stationary car with ambient lighting in a simulated environment. Tests performed involved changes in lighting color, luminance and the position of lights in a simulated driving environment. The emotional states of the participants were gauged at the beginning and end of the tests.

Elements within the study included design aspects (such as shape and material) and design principles (such as intended sportiness or luxury.) Purely functional aspects were also considered. Some participants were exposed to blue lighting and others to orange. The results showed that the blue lighting appeared brighter than orange lighting; drivers were able to find automotive control buttons and knobs easier in blue light, and blue lighting also gave drivers a better feeling of their orientation in low-light conditions. The downside of blue lighting was that it was considered "uncomfortable." In comparison, orange ambient lighting gave the perception of luxuriousness and better quality. With increasingly brighter levels of light, participants became more distracted and asked to be able to control it.

Results also found that carefully designed ambient lighting can decrease night-driving fatigue and is important for brand identity. Ambient lighting was shown to enhance night-driving safety and increase appreciation of the vehicle. The study indicated that ambient lighting can enhance the perception of spaciousness and quality of materials.

The Benefits of Automotive Ambient Lighting

Today, ambient interior lighting can be adjusted to the point of becoming a fashion statement; primarily only in high-end vehicles from Audi, Cadillac, Infiniti, Jaguar, Mercedes-Benz, and BMW. However, this technology continues to work its way down the chain to lower-cost models, albeit slowly.

LED ambient lighting was used initially as a cosmetic feature. While gentle ambient lighting can make a car's interior more attractive and affect consumer quality perceptions, many believe it can also increase driver safety. Most ambient lighting today reflects a light source off interior surfaces and is designed to help the driver see when he or she enters or exits the vehicle, manipulate driving controls, and impact mood, alertness and comfort.

But lighting must be functional as well as attractive. The number of lights, visibility inside and outside of the vehicle, level of distraction, driver alertness, immediate access to electronics, and the use of varying colors need to be at the forefront of a designer's mind as functional design aspects.

Today's Applications

LEDs are used in ceiling dome and map lights, backlit instrument panels, displays, controls, gear sticks and in door-panels to assist the driver as he or she enters, exits, and operates the vehicle. Interior lighting provides indirect illumination and provides a "wow factor" for design.

To date, many studies have researched the effects of lighting on mood, emotion and perception in buildings. Several studies exist on the effects of lighting on vision or safety in automobiles, but to date, a BMW study from 2009 has provided the most information regarding the psychological effects of automotive ambient lighting. Mercedes, Jaguar, and Land Rover are using LED ambient lighting to differentiate their vehicles. Mercedes offers a choice of seven colors with five dimming levels and four diming zones.

LEDs are also evolving with technology as exterior automotive headlamps. LED in headlamps have not only greatly lengthened life and increased efficiency. LEDs are much more flexible than incandescents in how they are able to automatically adapt to surrounding ambient light, and they are so small and light weight that they can be mounted with adhesives, screws, clamps, solder, or via any means that enables heat to adequately and evenly dissipate away from the LED. Newer, tougher semiconductor materials such as Galium Nitride (referred to as a "wide band gap" material ) enable operation at higher temperatures and with greater energy efficiency than LEDs of just 10 years ago.

LEDs have not only enabled specific customization of ambient interior lighting for color, brightness, intensity, and automatic adjustment to environmental changes, but exterior-use LEDs offer the same features in very high power, high brightness LED lighting a range of colors, too. For example, OSRAM Opto Semiconductors offers a broad selection of LEDs and modules that identify precise color, like the OSTAR Headlamp Pro: "The color coordinates of the LEDs correspond to the white field of ECE/SAE, in which the red component of the LED is greater than 5%...." LEDs are a technology that enable specifications for something we take for granted every day...light...and specifications enable designers to influence the automotive experience in precise, repeatable ways.

Figure 2: The OSRAM OSTAR Headlamp Pro LED has scalable brightness, adapts to ambient conditions, and mounts many ways, including soldering to a flexible printed circuit board as shown.

Looking Ahead

Future studies on automotive lighting may include the impact of lighting color and examine the extent to which ambient lighting helps or hinders tasks such as navigation. As more "things" become connected in the ever-increasing Internet of Things, it is likely that lighting will have a role to play, too.

The effects of ambient lighting are real and thanks to LEDs can be precisely specified and repeated, yet they must be weighed carefully against driver safety. So far, the automotive industry assumes that drivers will turn off or adjust lighting that disturbs or distracts. Interactive technology is working its way into lighting, however, as systems interact automatically to sense and adjust automatically. Automotive lighting can adjust automatically to save energy or offer a more comfortable experience by adjusting backlighting, indication, or styling based on the external environment as sensed by other automotive systems. For example, if the airbag is deployed, the internal lighting in the car might turn on to full brightness. Or if everything is fine but the car is operating only on battery, interior lights might dim even further to save energy or act as a warning. Changing interior lighting based on pre-set instructions from a smartphone app (based on GPS location or time of day) are entirely possible. Further advances in underlying technologies of automotive system communications with lighting, as well as improvements in the already-flexible LEDs themselves, will also have an impact not yet appreciated. Certainly, the trend for creative automotive lighting shows no signs of slowing down.

References

• i Wide Bandap
• ii OSRAM OSTAR Headlamp & Headlamp Pro - Details on Handling, Mounting and Electrical Connection, by OSRAM Opto Semiconductors.