Liquid silicone rubber is again playing an important role in new headlamp designs.
The first was developed by automotive lighting specialist Hella KgaA Hueck & Co. of Lippstadt, Germany, which introduced Multibeam matrix LED high-beam headlamps with a single complex LSR molding incorporating 84 light guides. That light was featured on the 2016 Mercedes-Benz E-Class cars.
Now the 84-LED headlamps have been introduced on the Porsche Panamera. Steffen Pietzonka, Hella's head of global marketing for lighting original equipment, said Porsche is using the same LSR part as on the Mercedes E-Class.
Osram said Hella is working within the µ-AFS 12 times higher resolution micro structured LED chip-based advanced front lighting system project in development of new “Smartrix” matrix LED lighting, aimed at adaptive light distribution with even more compact headlamps.
Roland Fiederling, automotive portfolio manager at Osram Specialty Lighting in Munich, confirms that among new materials contributing toward smaller and more durable “glare-free highbeam” matrix modules, “the first major development success was substitution of traditional materials for the optics with innovative alternatives made from silicone.”
Fiederling said the great benefit of the new Smartrix module is “long-life silicone optics enabling a particularly small and compact lighting system.” He said the first single-row Smartrix system from Osram for narrow low‑profile headlamps will be available on cars in fall 2017 and that Osram is already working on a multi-row generation.
LSR has been the obvious optical lens choice, Fiedler says, as thermoplastics cannot withstand thermal loads above 150°C in compact lamp designs and also age more rapidly when exposed to light in the blue spectrum as used with today's LEDs. Although glass can withstand the heat, the production cost is much higher than when injection molding LSR.
Fiederling is well-qualified to talk about LSR characteristics, as Osram injection molds and assembles LSR optics in its Herbrechtingen, Germany, plant. He talks of the challenge of handling silicone when molding optics due to extremely low viscosity, “similar to water.” He added that this has been one reason why LSR has not previously been used as a standard automotive high-quality optical component material.