LEDs Gaining Ground in Automotive Applications

The light-emitting diode (LED), a relative newcomer to thecentury-old automotive lighting market, may finally be gaining ground on thevenerable incandescent bulb.

A new breedof brighter, less costly, more efficient LEDs are making their way into a widevariety of automotive applications, ranging from center high-mount stop lamps(CHMSLs) and turn signals to vehicle cockpits and headlights. Moreover,applications for the technology are growing in unexpected ways. The 2010 FordMustang, for example, will use an LED-based feature called MyColor, whichallows drivers to customize the interior lighting of the Mustang to suit theirmoods. Similarly, Kia Motors' Soul has employed LEDs in its sound-reflectingspeaker lamp (watch a video of it),which responds with variable light to the beat of the music that's playing onthe stereo.

"More andmore automotive functions are using LEDs," says Viren Merchant, engineeringmanager for exterior electronics at VisteonCorp., a tier-one automotive electronics supplier. "In the beginning, its wasjust CHMSLs. Now it's everything from backup lights to rear fogs to daytimerunning lights."

Engineerssay the growing popularity of these electronic lights, which are based onthe semiconductor diode, is the result of several trends. Newer, brighterdesigns are said to be about 10-20 times more powerful than the products offive years ago. A few LED products now offer in excess of 50 lumens/W – insome cases as much as 100 – whereas many products a few years ago offered lessthan five. Meanwhile, electric vehicles and hybrids need power-efficientlighting, which boosts the appeal of LEDs. At the same time, the cost of LEDshas gradually dropped over the last five years.

"Five yearsago, there were no LED headlights," says Richard Vaughan, design manager in theInnovation Group for Visteon. "Today, LED headlights are optional on somehigh-end cars. And as the cost continues to come down, we'll see theproliferation of the technology in less expensive models."

To be sure,less than 2 percent of headlights are estimated to use LED technology today. Butsuppliers say that more than 80 percent of Asian cars use LED-based CHMSLs. Similarly,more than 70 percent of European cars and about half of North American cars are employingLED-based CHMSLs. On the exterior of the vehicle, automakers are also usingLEDs in daytime running lamps and parking lights, as well as the high- andlow-beam headlights.

In anticipationof increased use of LEDs in headlights, OsramOpto Semiconductors rolled out the OstarHeadlamp LED in November. The product is equipped with one to fivesemiconductor chips, in an effort to make it usable in a variety of differentheadlamp sizes and shapes. Depending upon the number of chips used, the unitproduces from 1 to 25 lumens at 700 mA (one chip) to 1,000 lumens at 1 A (fivechips).

Tier-onesuppliers say the design flexibility of the LED is a key to its growingpopularity. LED packages can be altered to incorporate different numbers ofchips, as well as different shapes and sizes. Automakers such as Cadillac, for example, have used thatflexibility to create unusually shaped CHMSLs and tail lamps.

"It's a wayto communicate to the consumer," Vaughansays. "Designers can achieve the shapes and length patterns that consumers cansee and identify."

In thatsense, LEDs are helping automakers create greater brand awareness, in theinterior, as well as the car's exterior. Osram, for example, has rolled outLEDs of various colors – including ice blue, blue lagoon, sky blue and bluegreen – which enable automakers to tune the interior color to match theirbrand. In an even bolder step, Ford isemploying the technology in MyColor, a system that allows drivers to change theinterior colors to match their moods.

"It tunes,not only the instrument cluster, but the whole ambience of car," says MikeGodwin, director of visible LED products for Osram Opto Semiconductors.

The idea,Godwin says, is to use LED technology to enhance a car model's image. "They usethe idea of color-on-demand to create a brand color," he says. "Their cockpitor their cupholder can illuminate in whatever way they want."

Tier-onesuppliers and LED makers alike say that LED adoption in automotive interiors isgrowing fastest of all. "Every interior request for a quote we've received fromevery manufacturer around the world the last two years has had some aspect ofLED ambient lighting to it," Vaughansays.

With theexpected proliferation of hybrids and electric vehicles, LED use is expected togrow faster still over the next decade. On those vehicles, where power is at apremium, engineers are more likely to disregard cost differences and reach forLED technology. "It saves about 400-430 Watts of power across the interior ofthe vehicle, and about 20 Watts on the interior," Godwin says.

At the sametime, engineers who want more brightness per W are getting that, too. InApril, Philips Lumileds rolled out the Luxeon RebelES, said to be the world's first high-efficacy power LED specified todeliver a minimum of 100 Lumens per W. The new product joins earlierLumileds entries that offered 30, 42 and 50 lumens. The new breed of brighterproducts is expected to take LEDs into exterior applications, such as red stoplamps, where they've been used sparingly before.

"Five yearsago, a red LED was one to five lumens," Merchant says. "Today, you can easilyget mid-20s in a red LED."

For now,most of the success of LEDs is being realized in luxury- and mid-levelvehicles, engineers say. Cadillac's Escalade, as well as selected Lexus andAudi vehicles, are employing LEDs across the board in high-beam, low-beam,daytime running lamps and parking lights. But as prices continue to drop andautomakers move to more energy-efficient vehicles, LEDs are expected to migratetoward entry-level cars.

"Incandescent bulbsaren't going away in the foreseeable future," says Merchant of Visteon. "But wedo know that LEDs are here to stay."