Few drivers take the time to consider anything about their headlights than whether they turn on. The story and technology behind them is interesting. If you know how your headlights accomplish the task, you’ll be able to maintain them more effectively and perhaps keep away from that moose or angry drifter in the road.
In the beginning
Either kerosene or acetylene was used over a century ago for headlamps. Small electric bulbs in a reflector/lens casing were then used after that. The lights would dim quickly from corrosion since insulation in old bulbs was a problem. Another problem with these lights -before the corrosion took its toll – was their intensity resembled constant high beams that blinded oncoming traffic, so the U.S. government made them illegal in 1941.
Other choices for light
Standard household light bulbs seemed to be comparable to Tungsten filament bulbs. Then there were high and low beam lights. These showed up in the 1920s. Brightness and overall beam control were inconsistent, which is not surprising, considering the bulbs were cheaply made. Quartz-iodine technology exchanged sealed-beam lights by 1973.
The next move
The standard headlight used today is the Quartz-Iodine (QI). The bulb is pretty much tiny. It is better protected too with the sealing materials we have today. The filament burns much hotter producing brighter light. This is because quartz glass can withstand very hot temperatures. When a QI bulb is changed, headlamps do not need re-aiming to happen. Modern filaments make this possible.
Trying out HD bulbs
High-intensity-discharge bulbs (HIDs) ditch the tungsten filament in exchange for a high-voltage arc that resembles a miniature lightning run. Getting on the HID light takes just a little bit far more energy. Keeping it on is much less energy than a QI though. Most observers claim an HID produces a crisper beam, but because they take a moment to reach full intensity, high-beams on HIDs could be problematic, particularly in emergency situations. For this reason, some modify HID arrays with QI bulbs for the high beams, but this can be prohibitively expensive.
Bulbs that shine like crazy
Taillights already use LED (light-emitting diode) lights, but they aren’t standard for headlamps yet. Popular Mechanics states that there is only one automobile where they’re standard. That is the Audi A8. Light in weight, vibration-resistant, bright and power-efficient, LEDs light up faster than a standard QI bulb, providing quicker warning that could be seen at greater distance.
If you don’t own an Audi A8 and want to experience LED car headlights now, there are DIY opportunities available, for instance the one described at the Instructables website. Keep in mind that because LEDs use so little power, conventional turn signal switches are not compatible. In order to get the right current going, you’ll need to switch them out.
Citations
Instructables
instructables.com/id/DIY-LED-car-headlights!/
Popular Mechanics
popularmechanics.com/cars/how-to/maintenance/how-your-headlights-work
An inside look at LED headlights
youtube.com/watch?v=wSkQ4h-sFiY
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