The Differences Between the Bulbs
Just as Edison’s invention has advanced, so has the modern-day headlamp. But if a customer asks you about the differences between lightbulbs, would you be able to shed any light on the subject?
In the beginning …
Automotive makers said, “Let there be light.” And there was light. But there were problems with the early headlamps, specifically that the filaments that powered the bulb had a short usage life in the harsh automotive environment. Early bulbs lacked the ability to produce sufficient light.
As technology advanced, tungsten filaments encased in a bubble of halogen gas became the industry standard. Thus, the halogen headlamp – born in about 1953 and still in use today.
How does halogen work?
The halogen lamp (aka quartz halogen and tungsten halogen) is an advanced form of incandescent lighting. Because the filament is encased in a halogen gas-filled bulb under high pressure, it has to be stronger than household lightbulb glass. It is constructed of fused quartz or high-silica glass to hold up under the pressure and heat.
Halogen bulbs are small, lightweight and cost-effective. They attain immediate full brightness and are dimmable. But they also have some drawbacks. Halogen bulbs run hot, and draw around 55 watts of power – much of it wasted by converting it into heat versus light.
As automakers continued to solve the drawbacks of halogen, ingenuity led to the next big thing: Xenon.
Xenon marks the spot.
Xenon high-intensity discharge (HID) bulbs improve on halogen with a premium, brighter, whiter appearance. Different from the filament used in a halogen bulb, Xenon HIDs use electrodes to charge the gas inside the bulb to produce the brighter, whiter light. Xenon HIDs also have a longer lifespan than halogen and require less power to operate (about 35 watts). They can have a self-leveling mechanism that keeps the light output more level and steady for the appearance of oncoming traffic.
Unlike halogen, however, Xenon HIDs have an adjustment period, meaning they need to be used a few times before they reach their full brightness potential. They also take a few seconds to reach full brightness when first turned on.
LED lamps solve some of those problems and have helped take lighting into a new generation.
The brighter white: LEDs.
Compared to halogen and Xenon HID headlamps, light-emitting diodes, or LEDs, have the coolest color temperature, which is why they produce such a clean “whiter than daylight” white.
LEDs are a big win for automotive designers because they are small and can be maneuvered into distinct shapes. They also draw very little power, minimize reflection on road signs and can last for up to 15,000 hours.
While it’s true that LEDs have a bigger price tag than Xenon HIDs and are slightly less bright, LEDs reach full capacity within 1-millionth of a second, compared to the ½-second HIDs take to fully illuminate. It doesn’t sound like much, but when LEDs are used in brake and indicator lights, they can help improve braking reaction time for other drivers.
Looking down the road …
Next on the cutting edge of headlight technology? Lasers. That’s right. Laser headlights are brighter (170 lumens vs. about 100 for LED), small, use less energy, and can be directed at a smaller area than LEDs.