The New York Times-20080127-So Efficient- L-E-D--s Are Now Fashion Plates- Too

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So Efficient, L.E.D.'s Are Now Fashion Plates, Too

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IN recent seasons, a new fashion accessory has become a must-have for the debutants of the auto-show circuit. No automaker introduces a new concept car, it seems, before dressing it up with L.E.D. jewelry.

Light-emitting diodes are replacing the car's trusty glass light bulbs much as compact fluorescents are replacing Edison's ancient incandescents in home lamp sockets. L.E.D.'s are longer lasting, more compact and consume less electricity.

Familiar as indicator lamps and later in powerful flashlights, the solid-state lights first found their way into cars as brake lights, an ideal application because L.E.D.'s illuminate more quickly than traditional lamps with wire filaments. Even if the difference is measured in milliseconds, L.E.D.'s can alert drivers sooner and help to prevent rear-end collisions.

Until recently, however, they have been about 10 times as expensive as traditional lights, according to LEDs magazine, a trade publication.

Now that is changing. Luxury cars are using the diode lamps in abundance, and they have already migrated onto more affordable vehicles.

L.E.D.'s have finally become cheap enough that we can spread the goodness around, said J Mays, group vice president for design and chief creative officer of the Ford Motor Company. Lincoln, Ford's premium brand, has broad bands of L.E.D.'s on the rear of some of its models. You have to have a way to handle them, said Mr. Mays. We have one for Lincoln that will reveal itself, he added, referring to future models.

L.E.D.'s offer bold possibilities for signaling brands and vehicle personalities.

Designers have developed a sweet tooth for L.E.D. eye candy. Younger designers in particular see the lamps as a token of the future and as high-tech jewels. They are deployed across every concept car -- from the face of the new Ford Explorer America concept to the turn signals of the Hummer HX, a design study for a smaller new model that would compete with the Jeep Wrangler.

Now L.E.D.'s are found in the taillights of most luxury cars: in the circular constellations of red stars in Infinitis, in bold horizontal bands on the liftgate of the Lincoln MKX crossover wagon, in a quartet of brand-signaling bands on BMWs and as hints of tailfins on the Cadillac DTS.

They have also begun to show up at the front end of cars as daytime running lights and turn signals.

Lexus offered the first L.E.D. headlight on the LS 600h L. Now Audi is able to claim the first all-L.E.D. lighting package for the front of a car: high and low beams of the R8 V-12 TDI Concept's headlights as well as running lights and turn signals.

L.E.D.'s appeal to engineers because in most cases they will outlast the cars in which they are mounted. And they use less energy -- a big attraction because the electrical systems of today's cars are already stretched to support entertainment systems, power steering and electronic controls.

But designers like L.E.D.'s for other reasons: they offer a whole new world of expressive possibilities.

They look very high-tech and precise and accurate, said Stefan Sielaff, Audi's head of design. This is part of our Audi design philosophy.

Precision and technology are important components of Audi's design theme, and its motto, vorsprung durch technik, or progress through technology. The Audi motto takes on visual expression in L.E.D.'s. The diode lamps, Mr. Sielaff said, also take up less space and give designers more flexibility in placing them.

The R8 lights are made by Automobile Lighting, a division of Magneti Marelli, a leading auto parts supplier based in Italy.

The Audi A5 coupe and the newest A4 have different arrangements of L.E.D.'s, more tubular in shape.

Each car needs a personality with lights, Mr. Sielaff said. I have an expert team doing nothing but light design. You do not just draw a pretty curve and see if it can be built. It takes working with engineers who know light itself, and the manufacturer of the lights and so on.

The first practical light-emitting diode, which was red, was developed in 1962 by Nick Holonyak Jr., an electronics professor who wanted to make a transistor do something he could see. Professor Holonyak, now the John Bardeen Professor of Electrical and Computer Engineering and Physics at the University of Illinois, soon realized the advantages: for each watt of electricity, L.E.D.'s produced more lumens, or units of light, and lasted longer than conventional incandescent or fluorescent light bulbs.

The diodes make possible all sorts of electronic wonders; they are used, for instance, in the superthin screen of the new Apple Air laptops. Another variation, called organic L.E.D.'s, hold the promise of being flexible -- future screens or lights may roll up like scrolls.

In headlights, L.E.D.'s make a light that is closer to daylight than traditional lamps, Mr. Sielaff said. The R8's lights have a color temperature, a measure of the light's hue, that is toward the blue end of the scale, at about 6,000 degrees Kelvin. Even brilliant rivals like the bluish xenon lamps measure below 4,000 degrees Kelvin, meaning they are yellowish. Blue lights improve contrast, make it easier for drivers to distinguish objects at night, and cut driver fatigue.

In the Audi R8's front lamps, a complex array of diodes is arranged in front of curved reflectors in a pattern that Audi engineers liken to a pine cone. Another portion of the lamp takes inspiration from the shell-like roofs of the Sydney Opera House. The complex taillights comprise more than 50 L.E.D.'s with various functions. Even the engine compartment, a carbon fiber container for the dramatically presented R8 powerplant, is lighted by L.E.D.'s.

Headlights are the eyes of a car, of course. But now the eyes need not be round like eyes. They can be narrow slits or twists, like the Ford Explorer America concept.

At their most extreme, L.E.D.'s can be deployed as stars or bits of eye candy, sweet and irresistible. But they can also be deployed in tubular fashion, like raspberry frosting from a baker's frosting bag. An example of using L.E.D.'s almost to draw is visible in the Mazda Taiki concept car, with headlights and taillights that bend and swoop to follow the body's shape, or the Mazda Furai, where the headlights are onion shaped.

The arrival of halogen lighting inspired lamp designers to all sorts of creativity, from the Tizio lamp to the dramatic creations of Ingo Maurer, recently displayed in the Provoking Magic exhibit at the Cooper-Hewitt National Design Museum in New York. New technology for automotive lights is likely to spur a similar burst of creativity.

[Illustration]PHOTOS: BRIGHTER: L.E.D. lights at the Detroit auto show, clockwise from left: Audi R8 V12 TDI concept; Mazda Furai; Ford Explorer America; Lincoln MKX; Hummer HX. (PHOTOGRAPHS BY BRIDGET BARRETT FOR THE NEW YORK TIMES; MIKE CASSESE/REUTERS; STAN HONDA/AGENCE FRANCE-PRESSE -- GETTY IMAGES (AUDI, MAZDA))