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Automotive lighting is at its most transformational stage since the U.S. government deregulated rectangular and round sealed-beam units in the mid-’80s. By 2019, two major safety-testing agencies (NHTSA and IIHS) will factor headlamp performance into their overall ratings of new cars, and award honors to the most effective. What now is a smattering of signature jewelry and elaborate reflectors is likely to get brighter, smarter, and cheaper, and we visited Osram Sylvania, a Tier 2 supplier and the only automotive lighting manufacturer left in the U.S., at its New Hampshire plant to find out what’s on the horizon.
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Halogen
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High-intensity-discharge (HID) headlights, in which xenon gas is used to create a precisely focused, bluish-white arc of light at a fraction of the wattage required by incandescent bulbs, are pricey enough that they remain optional even in the premium segment. It’s been more than 20 years since BMW fitted the first HID headlights to the E32 7-series and the 1996 Lincoln Mark VIII became the first American car with HIDs, yet halogen bulbs are so inexpensive and effective that mainstream automakers can’t fully abandon them.
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About 80 percent of the market relies on these little pressurized tungsten-filament bulbs. Their unit cost is roughly $5 compared to $30 to $40 for LEDs (HID runs somewhere in between), but they’re not all that inferior, says Osram Sylvania. Today’s halogen bulbs are manufactured under extremely tight tolerances. Cameras at each station in Osram Sylvania’s plant automatically toss out defective product that 15 years ago would have been shipped, we’re told. The top-line bulbs are even filled with xenon gas and coated in blue tint to mimic HIDs, although their shortened functional life restricts them to the aftermarket. Since halogen bulbs have standardized plastic sockets and run straight off the car’s battery—instead of requiring an AC inverter for an HID setup—they’re easy to replace. Eventually, they’ll be as antique as acetylene lamps, just not yet.
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LED
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Within four years, Osram Sylvania predicts that LED headlamps will be installed in 20 percent of all new cars. The Toyota Corolla and Ford Explorer come with standard LED low-beams, and as fuel-efficiency regulations tighten, LED headlights will play a key role in reducing energy consumption. Indeed, they each draw between 15 and 18 watts of power, versus 55 to 65 watts from a halogen and 42 watts from an HID. Their response from off to full strength—known as “rise time”—is just one millisecond. An incandescent bulb is 250 times slower, which makes LEDs especially advantageous for brake lights. There’s no question that LED headlights are brighter (3000 lumens at low beam versus 800 lumens for halogen) and output light at a color temperature closer to daylight (5500 Kelvin versus 4500 for HID and 2500–3000 for halogen).
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But the biggest drawback, now and in the future, is high production cost. Automakers investing in LEDs are eschewing standardized fitments. On the Explorer, for example, the LED headlight is actually side-mounted and reflected forward as opposed to the projector-style LEDs in a Toyota Prius. Audi and Acura line up individual LEDs like polished gemstones, Lexus stacks them into a triangle on the RC F, and the Ford F-150 exposes LEDs in a style reminiscent of thick ice cube blocks. Every LED headlight requires custom-printed circuit boards with more than 130 components, custom aluminum heat sinks, custom reflectors, and a custom resolution (the number of LEDs per unit)—and that’s before they’re mounted into a finished, custom headlight assembly.
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Since automakers refresh or overhaul their models every three to six years, lighting manufacturers can’t bear the expense of retooling large-scale assembly lines for what ultimately are proprietary, low-volume products. Human hands in static- and humidity-controlled clean rooms control a significant portion of the LED manufacturing process, from the first wiring connectors to the final screw mounts, which further limits production capacity and increases per-unit cost. For example, Osram Sylvania cranks out more than 100 million halogen bulbs a year, 24 hours a day. It can only make 130,000 LED headlights for the F-150. If LEDs are to be commodities, automakers must standardize more of these lighting components.
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LED Matrix
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LED matrix headlights that can actively shade and illuminate sections of the roadway are currently illegal in the U.S. Osram Sylvania expects NHTSA to approve the technology next year, although the agency has not issued a formal public proposal as part of the rulemaking process, which may delay the rollout. We won’t bet on a timeframe, but better matrix headlights are already on the way. The next Audi A8 will have 1024 individual LED pixels on a single chip, as compared to eight on the current Euro-spec car. When coupled with smarter software and more sensitive infrared cameras, these high-definition headlights will be able to activate specific LEDs to illuminate pedestrians while blacking out their faces or brighten speed limit signs without flooding someone’s living room. Like an LED TV, higher pixel counts will improve a headlight’s sharpness and clarity, but only so far.
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Laser
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Laser headlights may be that next step, if the U.S.-market safety and regulation issues can be sorted in a reasonable amount of time. The BMW i8 uses three Osram Sylvania laser diodes that beam blue light through a ceramic phosphor platelet, converting the beams to a single white “point source” able to project a wide span of light up to 1969 feet. That’s 10 times the luminance (the number of candelas per square meter, or essentially, how a bright a surface looks at a given angle to the human eye) than an LED headlight. So far, BMW is using lasers for the high beams, and the next-gen lights will use just one laser diode at one-third the price.
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- NHTSA Overhauling Crash Tests for 2019 Model Year Cars
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- IIHS Headlamp Tests Find Many New Cars in the Dark
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- BMW Beats Audi to Production Laser Headlamps, World Keeps Turning
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With laser headlights, smaller apertures allow designers more flexibility and engineers the capability to modify the beam as a spotlight, such as to illuminate pedestrians (BMW also uses this technology overseas, called Dynamic Light Spot, on non-laser fog lamps). In the future, the best headlights may use a combination of laser and LED matrix technology. But longstanding regulations—and the high cost of supporting bespoke headlight designs—will continue to keep most of us in a relatively darker place.
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from Car and Driver Blog http://blog.caranddriver.com/out-of-the-dark-the-future-of-automotive-headlights/
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