Injection molded acrylic lenses are the centerpiece of a new generation of automotive headlamps developed by Magna International Inc. Introduced as standard on higher trim levels of the 2018 Chevrolet Traverse, Magna's D-Optic LED headlamps offer the efficiency gains of LEDs along with customizable styling options for automakers looking to differentiate their brand, the supplier says.
Magna engineers sought to simplify conventional optical systems in which multiple components — reflector, shield, lens — must be positioned very precisely, said Cole Cunnien, director of engineering for Magna's lighting group. They developed a system of pairing a precisely molded lens with a single 1x1 LED light source.
"The D-optic system is just one optic on top of the LED, so we eliminate the stackup with this," Cunnien said.
D-Optic lenses come in four unique "prescriptions," which can be combined in different configurations to meet specific performance requirements.
The Magna team chose acrylic over polycarbonate for its better stress resistance. The lenses are molded in a single shot, with part thickness varying from 1.5 millimeters to up to 18mm, and "the brittleness [of PC] caused us a lot of heartburn," Cunnien said.
They found a high-temperature grade of acrylic that enables the lens to be placed very close to the light source — within 300 or 500 microns — to maximize the amount of light captured from the LED. The material, which is formulated for lighting applications, is also used in the light pipe on the perimeter of the Traverse headlamp. Cunnien said the material provides good optical clarity but is sensitive to contaminants and fluctuations in moisture content.
Magna manufactures the headlamp assemblies at its new, 140,000-square-foot lighting facility in Plymouth, Mich. A specialized manufacturer in Indiana supplies the lenses, using highly polished tooling and laser degating. Each side of the lens is created using an insert — "put together like a jigsaw puzzle," Cunnien said — perfectly fitted to produce no flash.
The Traverse headlamp, which was custom-designed for Chevrolet, incorporates nine elements — nine individual lenses on top of nine LEDs. Magna's original proposal was for 10 elements, Cunnien said: four large lenses and six smaller ones. But for aesthetic reasons they were asked to produce a design with an odd number of large elements, resulting in the final configuration of three large lenses next to six smaller ones, which were tweaked to produce the same performance.
That design flexibility is a key advantage of the D-Optic system, Cunnien said.
"The automakers always want the ability to differentiate their products from others," he said. "... The modular nature of this, we can basically say, 'Here are your building blocks; you can put together your dream home however you want with these blocks.' "
The D-Optic system is pricier than a conventional headlamp assembly but, as is typical with optional upgrades, automakers bet on the customer's desire to set themselves — and their vehicle — apart. GM is offering the lamps as standard on the High Country and Premiere trim levels of the Traverse.
"They want to see something different. The technology has to look different," Cunnien said.
Magna's lighting group, based in North America, is working to expand globally as automakers increasingly consider global capability in selecting a supplier. The division currently has facilities in Canada, Mexico and the U.S. and will soon be establishing manufacturing in Asia and Europe, Cunnien said, offering headlamps, tail lamps and other lighting along with full systems integration.