Click Image to Enlarge
In order to facilitate the use of LEDs, OSRAM designed the Joule system as a standardized system to replace a traditional light-bulb-and-socket setup.
Hella’s LED array for a headlamp includes seven LEDs with five chips controlling them is an improvement over the typical 1:1 chip-to-LED ratio found in most applications. The company is working on systems to control up to 80 LEDs with only a handful of chips to create a multitude of lighting scenarios.
The 2010 Mustang, seemingly, has many moods. The car can be imbued with shades of green, icy blue, dark blue, orange, red, and white. Ford calls this ambient lighting system "MyColor," a premium option now in its second generation, which uses an electronic "palette" to mix and match the lighting of instrument cluster, front and back footwells, cup holders, and doors to essentially "personalize" the interior.
This is one—some might say limited—future for light emitting diodes (LEDs) in cars. That is, using solid-state lighting as an option to customize a specific car brand or even particular vehicle. More than mere ornamentation, LEDs provide an energy benefit: the lighting system saves the car an estimated 10.5 gallons of gas a year. Still, the interior is not exactly the LED future that many dream about. That version illuminates a car with LEDs from headlamp to tail lamp, from side markers to turn signals, from LED-enabled infrared sensors that manage advanced safety systems like lane departure warnings to smart highbeams that can tell the difference between a deer and a kid on a bike.
And there is potential this could occur. New emissions standards could help push more LEDs to the fore and a European Union (EU) mandate requiring all vehicles sold there to have daytime running lamps by 2011 could further democratize the technology. LED-powered daytime running lights (DRLs) are 75% more efficient than the standard versions, according to a recent study. (See box at end of article.)
But before OEMs can completely customize their vehicles with LEDs, the industry will first have to institute far more standardization to lower costs.
The Bulbs and the Breakthroughs
LEDs are semiconductor devices that emit visible light when a relatively small amount electric current passes through them; they typically use less than a quarter of the energy of an incandescent bulb. And depending on how it's calculated, an LED bulb has at least a 10,000-hour lifetime and some claim up to 50,000 hours, while an incandescent bulb's life is around 1,200 to 1,500 hours.
This, too, is well known: LEDs, in high-power applications such as headlights, cost double or even triple that of a conventional unit. With Japan viewed as an early LED adopter in both luxury and some mid-market models and the EU following closely behind, the North American market is increasingly the focus for LED makers. Yet David Hulick, global product marketing manager at OSRAM Sylvania's Automotive LED Systems Strategic Business Segment (sylvania.com), doesn't overstate the opportunities. LEDs, Hulick is fond of saying, are important for energy efficiency, but don't carry the same obvious air-clearing impact to the public that fuel injection did in sidelining the carburetor two decades ago.
"Certainly, LEDs will become the major light source for some applications, but conventional halogen and incandescent lighting will be with us for a long time, based on the infrastructure and the fact that…there is nothing wrong with them," he says.
LEDs now dominate the tail and center-mounted brake light markets. What's more, LED backlighting in the instrument panel currently exceeds more than 50%, and a July 2009 Frost & Sullivan forecast estimates that number will jump to 80% by 2015. The same survey predicts LED headlamps will reach 26% of the market by 2015, mainly by cutting into the 66% share that halogen lamps enjoy (as of 2007). Yet LED headlamps will not approach price parity with the 20-year-old xenon high-intensity-discharge (HID) systems until 2025 or even beyond, the study goes on to report.
OSRAM designed the Joule system
LED cost decreases will only follow power efficiency improvements, Hulick says. OSRAM is on a trajectory of 50% system efficiency gains annually over the next five years. The company is focusing on a family of "plug-and-play" LED systems, called "Joule," designed to easily replace a traditional light-bulb-and-socket setup. The systems give OEMs such as Ford, which has been using them since 2005 in tail lights among other applications, the option of adding LEDs in secondary or tertiary model production runs or model refreshes, instead of investing in the engineering to accommodate LEDs at the beginning of development. OSRAM is working with multiple OEMs and Tier Ones in developing headlamp systems using the Joule product in forward lighting.
"These systems are replaceable, scalable, and minimize the technology disruption of using LEDS," Hulick says. "Because the LED you bought five years ago may no longer be available now."
At OSRAM competitor Philips Color Kinetics, Ingolf Sischka, product manager aftermarket-Philips Automotive Lighting North America (lighting.philips.com/us_en/index.php?main=us_en&parent=us_en&id=us_en&lang=en), says the chemistry of the LED is where the biggest potential energy leaps still remain. In Philips' most recent consumer-focused replacement bulb, the EcoVision, the company changed the argon, krypton and xenon recipe by significantly upping the amount of xenon, which has increased the light output with less wattage.
"The amount of light you get from certain power consumption, say one or two watts, is twice or three times more than what you got out of an LED two to three years ago," says Sischka. "The material chemistry and LED technology as a whole are still developing rapidly."
Pulling it Together
There are limited numbers of complete LED headlamp systems on the road, as most are paired with high-intensity discharge lamps (HIDs). Steffen Pietzonka, vice president of marketing for Hella KGaA Hueck & Co.'s Lighting Division (hella.com), says that is changing quickly as more HIDs will transition to LEDs, initially within luxury vehicle applications and with incandescents following suit, slowly. "We see in nearly every project coming to development for 2012 to 2013, nearly every headlamp will have at minimum a front signal function with an LED, mainly for daytime running lights and styling reasons," says Pietzonka, who adds he is aware of seven OEMs introducing 10 models with full headlamp LEDs in the U.S. and Europe, and another 10 to 13 models in Asia within the next four years. "We see in the future, the end consumer won't accept an LED with separate low- and high-HID beams."
That perspective is persuading Hella to both simplify the lamp package and experiment with alternative materials to reduce weight, while attempting to get more OEMs to buy into LEDs for smaller-scale exterior applications, such as fog lamps. For instance, the 2008 Cadillac Escalade Platinum, which included both low- and high-beam functions in one LED created by Hella, demonstrates the complexity. For just the low beam, the headlamp consisted of five lenses arranged underneath one another at the outer edge of the housing and two more for the high beam. Pietzonka says Hella is developing various thermoplastics that can perform the same function as glass lenses, but at 1/3 the weight. They're creating down-market LED headlamps that are less sophisticated and could go into midsize and compact cars by 2013.
Outside of LED headlights, Hella is designing ancillary exterior lighting systems, including a fog lamp for the 2010 Taurus, which uses a single, 1-watt LED. The company wants to apply the same concept to several other systems, including turn signals, side markers and DRLs, which is prompting a shift in how they're manufactured.
"All of these new designs are forcing us to move into new molding processes; so now you need to have two-shot injection molding machines to make them. In the lighting business, these are new techniques," says Carlos Visconti, vice president of NAFTA Product Development Lighting for Hella. "These pieces have to be perfect. If you have a bubble in the plastic and you throw light through the pipe, the bubble will completely distort the distribution of light."
Improved efficiency from the LED bulbs has downstream consequences for system integrators planning in five-year automotive program increments. "The efficiency gains have a very important impact on us and mostly on the headlamp manufacturers," says Max Austerer, of Continental (conti-online.com) AG's Body & Security Business Unit, which makes electronic control units (ECUs) for Tier One headlamp manufacturers. "As the LEDs get more efficient, it will mean less cooling power and fewer fans will be necessary." That's a good thing, but at the same time, "the bottleneck is there are only a few integrated circuits out there and they're very expensive," says Austerer. Continental has started designing its own integrated circuits for the ECUs that manage a wide range of LED power loads so engineers have more flexibility in integrating them with headlamp subsystems.
Chips and Future Apps
Chipsets may eclipse all other obstacles in getting LEDs into the car. In most applications today, there is a 1:1 ratio of chips to LEDs. That's not going to cut it long term for LEDs with more features. Hella is developing an array that places multiple LEDs on a single chip substrate to create hundreds of lighting distributions, including one that manages 80 LEDs from eight chips. "You need very good image processing and a camera to see if it's a tree, a human or just a box on the road," Pietzonka says. "That needs very, very good software and that's one of the main barriers at the moment."
At the same time, as LEDs become more capable and fewer chips are necessary. A single bulb may command a multitude of patterns. "I can envision an LCD projector that uses micro mirrors and you can address lighting pixels one at a time," OSRAM's Hulick says. "Imagination is the biggest obstacle right now. The industry has to be willing to do things differently and it isn't that easy."
Measuring the Change
A motivation for moving toward LEDs is improving fuel economy. How much LEDs can actually save in fuel costs was evaluated in a 2008 study by the University of Michigan’s Transportation Research Institute (UMTRI). The research looked just at power consumption of exterior lighting on passenger vehicles by comparing a traditional system using 100% incandescent and halogen light sources with a 100% LED system. The results showed that an all-LED system employing the current-generation systems would mean lighting power savings of about 50% at night to about 75% for daytime running lamps over a traditional system.
In a gas vehicle, a complete LED exterior system would save the driver between $5 and $17 in fuel costs per year, based on a 15,000-km annual driving cycle. For electric vehicles, however, the savings with LED lighting extend the range on each battery charge by up to 1%, or about one full battery charge per year.
But Brandon Schoettle, a research associate who co-authored the study, says an all-LED car would reduce the vehicle’s total carbon output by 1 to 2% a year, a significant improvement. “To have some seemingly left field part of the car help you save 1-2% on emissions is pretty exciting,” he says.