Illuminations: Where Light Takes the Lead

Tony Armstrong from Linear Technology, now part of Analog Devices, explores the ongoing changes in LED headlamp technology.

Remember those old tungsten filament light bulbs? The common 40 and 60-watt incandescent bulbs, once a staple in American homes, were banned from production and import in the U.S. by the end of 2013, though they’re still available for purchase. The 75 and 100-watt versions were phased out a year earlier in 2012.

The push to eliminate these incandescent bulbs came primarily from the U.S. Environmental Protection Agency (EPA). The goal was to boost efficiency in converting electricity to light, thus cutting down on power consumption. Household lighting made up roughly 14% of the country’s electrical use, so improving light bulb efficiency was a big deal.

That’s where solid-state LED lights come in. They use about one-eighth of the power needed for traditional bulbs to produce the same brightness, making them a staple in today’s lighting solutions.

The shift from incandescent to solid-state lighting mirrors changes we’re seeing in vehicle lighting technology. Red LEDs have been lighting up our car’s taillights for over ten years now. More recent advancements have seen LEDs increasingly used for car interiors and forward illumination. For instance, over 70% of interior indicator lights and nearly half of instrument display backlights are now LEDs.

Look at daytime running lights (DRLs), where LED usage is over 55%. But when it comes to headlamps, only about 5% currently use LEDs. It seems odd since headlamps are a huge potential market. The main hurdle? Cost. Car manufacturers are finding it challenging to implement LED headlamps at a price attractive to consumers.

Let’s dig into why LED headlamps are so appealing to drivers and manufacturers alike:

1. Performance and Design Flexibility: LEDs offer a lot of design freedom due to their small size and provide diverse dimming options. The human eye can quickly notice even slight changes in light output.
2. Energy Savings and Lower Emissions: LEDs are more power-efficient, which translates to energy savings and longer lifespans, ultimately reducing carbon emissions.
3. Cost Efficiency: Although they might seem pricey initially, especially in non-headlamp applications, the decreasing costs over time, coupled with their durability and quality, make LEDs more cost-effective in the long run.
4. Regulations: Government standards for DRLs, headlamps, and other lighting applications have spurred demand for LED lights.

Audi stands out as a leader in using LEDs for exterior automotive lighting, with their distinctive eyebrow DRLs becoming a recognizable feature. Audi was also the pioneer in using LED headlamps in its 2004 R8 model.

So why haven’t LED headlamps become as widespread as other LED automotive lights? The simple answer is cost. Alternatives like incandescent bulbs, halogen bulbs, and HID Xenon bulbs are cheaper. LEDs for headlamps can be twice as expensive as halogen lights and 1.5 times the cost of HID Xenon bulbs. Plus, to match the performance of HID Xenon headlamps, you need a far more expensive LED setup.

In summary, while LED headlights are still in the minority, they sit between halogen and HID Xenon lights in terms of cost and performance.