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THERE ARE plenty of reasons for more automotive lighting of the Light-Emitting-Diode variety. LEDs are more efficient than conventional incandescent illumination. They give stylists great opportunity for originality. They offer adaptive technology for reduced glare. And their prices are coming down.
But enhanced automotive lighting of the LED variety requires a change in government regulation. Adaptive automotive headlights are not yet legal.
Conventional lighting shares the incandescent nature of Edison’s first bulb. It may have a halogen atmosphere within the bulb (today’s basic headlamp type). It might have a metal halide with a xenon-gas arc discharge for startup (as in premium xenon lighting). But its incandescence still produces heat—and this heat eats energy.
By contrast, an LED passes electricity through a silicon diode, a semiconductor one-way switch. It generates light, not heat.
Today, LED elements are used in high-end lighting, though a mere 2 percent of automotive applications. But Osram, a major supplier of automotive lighting of all sorts, predicts that LED applications will account for 20 percent of the market by 2020.
Cost is still a big factor. According to Automotive News, September 16, 2013, a basic halogen headlight costs an automaker around $20; a premium xenon headlight, from $60 to $80. An LED equivalent is roughly twice as expensive as xenon, but prices are declining rapidly.
For reasons of efficiency, packaging and styling, Toyota has shown interest in adaptive LED applications.
See www.wp.me/p2ETap-16K for information on Toyota’s use of LED arrays with shutters achieving antiglare characteristics and low-beam operation.
Osram has introduced an adaptive headlight that doesn’t require mechanical shutters. Each LED matrix consists of 78 selectively aimed elements arranged in three rows of 26 each.
High-beam is characterized by operating all 78 elements. A windshield-mounted camera monitors surroundings; its computer shuts down appropriate elements to minimize glare. No mechanical shutters are used.
The reduction might be in response to an on-coming vehicle. Or it might be reducing glare when one car passes another. The number of elements in the matrix gives optimal flexibility in control and illumination.
At the recent Frankfurt auto show, Audi exhibited an A8 with similar Osram hardware. Each headlight’s high-beam has five light bars with five LED elements per bar.
Though legal in other parts of the world, current U.S. regulations prohibit any sort of adaptive high-beam. NHTSA and SAE International have research projects addressing potential changes of the regulation.
At this point, LED matrix headlights are prohibitively expense for mass production. However, rapidly declining LED costs will change this. ds
© Dennis Simanaitis, SimanaitisSays.com, 2013