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LIVONIA, MI – Light-emitting diodes, the tiny, energy-saving devices that are displacing incandescent lamps in many automotive applications, now illuminate 90% of center high-mounted stop lights (CHMSLs) in the U.S. and about 15% of the combination taillights.
But supplier 3M Automotive has developed a unique way to package LEDs that could send the latter penetration rate skyward by saving weight, space, electricity, material and, perhaps most importantly, money.
Taillamps relying on LEDs currently can require dozens of diodes to generate the necessary illumination. 3M’s new Uniform Lighting Lens needs as few as four standard LEDs to do the same job.
The key element of ULL is the micro-patterned polycarbonate inner lens that absorbs the light and distributes it more uniformly, allowing the surface to glow like molten steel.
The ’13 Buick Enclave is the first production vehicle to use the technology.
ULL requires less space and can be packaged in thin-profile light modules. The technology also frees stylists to think unconventionally because the automotive-grade polycarbonate is thermoformable and can accommodate custom shapes.
For instance, the word “RAM” could be pressed into the lens of the taillamp for the owner of a Chrysler fullsize pickup truck.
“We’re seeing auto makers trying a lot of interesting things in the area of lighting,” says Jeff Boettcher, new business development manager for 3M Automotive.
“Some of them are mixing incandescent lights with LEDs, because it allows an OEM to create a unique appearance to identify their brand driving down the road,” he says. “They want the ability to identify a car in the evening and during the day.”
In many LED taillamps, the diodes are positioned to shine directly toward the lens.
But with the ULL design, 3M achieves smooth, even illumination by positioning the LEDs in the center of a reflective chamber capped by the polycarbonate inner lens.
With so few LEDs, the lighting cavity can be extremely thin. A working prototype carries a depth of less than 1 in. (25 mm) while many lighting cavities in production today are three times as deep, says Brian Ostlie, senior technical manager-lighting for 3M Automotive.
With four LEDs, the ULL is as bright as any other production taillamp, Ostlie says. But adding a few more LEDs significantly increases brightness if more is necessary to meet photometric requirements.
As LEDs have gained popularity in automotive applications, they have come down in price. At one time, the diodes carried a steep cost premium over incandescent lamps, but today they are about 30%-50% more expensive, Ostlie says.
3M declines to discuss overall cost savings because the polycarbonate lens is merely one piece in a complex light assembly marketed by Tier 1 suppliers directly to auto makers. Pricing is hashed out at that level.
But the ULL should carry a lower cost because there are fewer LEDs, which requires a smaller circuit board and fewer capacitors and resistors.
There are a number of potential customers for the technology.
“With the general trends in signature lighting, there are lots of people interested in this technology,” Boettcher says.
3M displayed ULL at its 2012 Transportation Summit hosted at the supplier’s offices here. In addition to automotive, the event highlighted technologies for commercial and recreational vehicles and the military and aerospace sectors.
