Rudy Ramos, Mouser Electronics
A friend and I recently went on an evening cycle ride, and because I knew we would be riding in the dark for part of the time, I took my CatEye OptiCube light with me. It was attached to my front handlebars, meaning that when I steered my bicycle around corners, it was always lighting up the section of path or road I was heading toward. Consequently, I always knew what lay ahead.
As we were riding, I realized that what I was experiencing was similar to the adaptive front-lighting systems (AFS) that car manufacturers are starting to use in increasing numbers.
Using Lighting to Improve Safety
It is estimated that 90 percent of all the decisions we make while we are driving are based on information that our eyes send to our brains. Driving in darkness significantly affects our ability to judge distances accurately, making it more difficult for us to make the best possible decisions.
To improve safety after dark, car manufacturers are therefore looking at how to use lighting to improve visibility for drivers and thereby give them a greater awareness of whatís around them.
A key part of this drive is to replace traditional halogen or high-intensity discharge (HID) lamps with LEDs. LED technology has developed significantly over the last 10 years, LED-based lighting has matured enough for many automakers to use for all of their automotive exterior and interior lighting needs.
The advantages of LEDs are many, and their characteristics make them perfect for automotive lighting: they are compact, reliable, heat-tolerant, highly energy-efficient, and can switch on and off at high speeds. Consequently, they give vehicle designers new opportunities to improve passenger safety.
For instance, LEDs are ideal for AFS, because they can be placed in or on many parts of the vehicle. It is also possible to change the shape and intensity of the LEDís beam in response to prevailing conditions.†Daimler AG, for example, is using LED technology to power itís Mercedes-Benz LED Intelligent Light System (ILS).
Dynamic Automotive Lighting
All drivers will be familiar with switching between dipped-beam headlights (the standard night-time setting, suitable for use when there are other vehicles around) and full-beam ones (for lighting up the road farther ahead when thereís no other traffic). In most cars, this is done manually, but manufacturers are developing systems to automate this switching, using light sensors in the vehicle.
Moreover, by using LEDs, it is possible to offer more than two brightness settings, because this type of light can easily be dimmed.
A likely scenario would, therefore, be for car makers to design lights that vary smoothly between dipped-beam and full-beam. This capability could, for example, automatically raise the beam in line with the carís speed. After all, the faster you are going, the more time you need to react to something ahead, and the better illuminated it is, the more chance you will have of reacting most appropriately.
Like the light on my bicycle handlebars, car makers are changing their headlight designs to respond to the steering angle. This is done by bringing together data from sensors located around the vehicle, including some in the steering wheel and others that look at the road ahead. This gets combined with information on the car’s speed, its pitch relative to the road, and its turning rate. These insights enable the car to rotate the headlight beam horizontally to give the driver the best possible view of what lies ahead.
Moreover, the headlights are not the only part of the story: other, strategically positioned lights can be automatically switched on to improve visibility as the car approaches and turns corners.
New Generations of LED-Based Vehicle Lighting
A long-term player in the automotive lighting market is Lumileds, now the leading lamp supplier to the auto sector, found in a third of vehicles sold globally.†Lumileds has launched two AFS product lines: the Lumileds LFMH/A LUXEON F LEDs and the Lumileds LAFL LUXEON Altilon LEDs.
Lumileds LUXEON F LEDs
These are 1.9 mm by 2.3 mm high-power LEDs, see figure, are designed to help AFS and other functional intelligence systems, matrix applications and light guides. LUXEON F lamps are available in different colors and can be used for AFS dipped-beam and full-beam purposes, front fog lights, parking lights, daytime running lights and indicator lights.
Tested for use at up to 85įC, the LUXEON F lights meet ECE and SAE color specifications, while offering finer granularity than other systems present in the market.
The F lightís compact footprint enables denser designs, and with the package being undomed, it can achieve exact optical control. Moreover, the low forward voltage and some of the industry-lowest thermal resistance means less space is required for heatsinks.
Lumileds LUXEON Altilon LEDs
The Altilon LEDs are all about delivering bright white light for forward-facing lighting. Created with ease of optical design, manufacturing, and assembly in mind, their 1A drive current means each package delivers high light output. Consequently, vehicle makers do not need as many of these LEDs in their designs as they might otherwise.
Able to withstand temperatures up to 150įC, the Altilon range offers very low thermal resistance, which again means heatsinks can be kept small. Moreover, like the LUXEON F, Altilon LEDs meet ECE and SAE color specifications and offer finer granularity than existing systems in the market.
This range uses advanced phosphor technology and is available in either 1 x 2 or 1 x 4 configurations, both with or without spade lugs. Production part approval process (PPAP) documentation is available, and the Altilon LEDs are AEC-Q101C compliant.
Join the Future of Automotive Lighting
New LED technology from companies such as Lumileds, combined with AFS and other smart vehicle lighting systems, means it is an exciting time for automotive lighting designers. Are you ready to become part of this worldwide community thatís changing the way we see our cars?
About the Author
Rudy Ramos is the project manager for the Technical Content Marketing team at Mouser Electronics and holds an MBA from Keller Graduate School of Management. He has over 30 years of professional, technical and managerial experience managing complex, time critical projects and programs in various industries including semiconductor, marketing, manufacturing, and military. Previously, Rudy worked for National Semiconductor, Texas Instruments, and his entrepreneur silk screening business.