Bright lights, bold look

Engineered polymers and LEDs pave the way for advances in automotive lighting. Automotive OEMs use distinctive styling cues to differentiate their vehicles from the competition. While body styling continues to be a priority, automotive lighting is beginning to emerge as a key design element. Advances in lighting technologies, the desire for distinctive designs and incorporation of color combine to give lighting assemblies bold new looks. Outer lenses for automotive headlamps have typically been molded from polycarbonate (PC) resin. PC is also increasingly used for inner lenses. PC is well suited for automotive lighting thanks to a combination of high-impact strength, clarity, thermal stability, heat resistance, and ease of injection molding for complex lens designs. But such recent advances in lighting as light-emitting diodes (LEDs) are complicating the process of picking materials and creating innovative designs. Fortunately, PCs continue to evolve with new grades that are up for the task. Over the last few years, LEDs have worked their way into automotive lighting — as tail lamps and CHMSLs (center high-mount stop lamps) where PCs serve in bezels and housings. Now LEDs are going into headlamps. The 2007 Cadillac Escalade headlamp assembly, for example, features a row of seven amber LEDs packaged behind amber inner sidemarker lenses molded from Makrolon PC. The headlamp outer lens and chrome bezel are also made from Makrolon PC. This application is significant in that it signals a bright future for LED technologies in such uses. In fact, white, high-brightness LED (HB-LED) lumen output has steadily risen to a point the bulbs are used on commercial vehicles behind PC lenses in forward lighting day-time running lamps. Automotive OEMs and lighting suppliers are taking the next step: Transforming LEDs from a point light source into a legal beam pattern, thereby paving the way for HB-LEDs in vehicle forward