Headlights are usually an afterthought on vehicles unless one of them burns out. Beyond helping a vehicle look cool, ugly, silly, or stylish, many forget how much of a role they have in driver safety.
Like just about every other kind of technology packed into vehicles nowadays, headlights have become safer, more complicated, and more technologically advanced over the years.
You can certainly reap the benefits of knowing a little about headlight technology since they are usually one of the most commonly replaced parts on your vehicle, and there are probably more types of headlights than you realize.
Headlight Bulbs vs Headlight Housings
Usually, when people think about headlights, they are thinking about the actual bulbs that produce the light rather than the housings in which the bulbs reside. The headlight housing is what you can see from the outside of the vehicle, and they are one of the primary styling components on the front of a vehicle. Of course, they also take the light produced from the bulb and disperse it.
Even though both types of headlight housings come with their own forms of technology, headlight bulbs are the components that carry most of the technological weight within the realm of headlights.
Types of Headlight Housings
There are two main types of headlight housings: reflector and projector.
Reflector headlight housings are the most commonly used, but they are also the most basic. They consist of a bulb that is surrounded by mirrors that reflect the light of the bulb forward, dispersing the light. They look like a bowl with flat surfaces on the bottom and a pin in the middle. This “pin” is where the bulb is housed, and flat surfaces within the “bowl” are the mirrors. A clear lens protects the outside of the housing.
Reflector housings are usually simpler, and therefore less expensive than projector housings, but they cannot concentrate the headlight beam as well as alternative housing types. This lack of light concentration can be more dangerous to oncoming traffic in terms of visibility than other types of housings.
A projector headlight housing functions very similarly to a reflector housing on the inside, but rather than a reflective “bowl”, projector housings use a lens that looks like a projector bulb to focus and magnify the light produced by the light bulb. Projector low beams are often coupled with reflector high beams to fill out the look of a vehicle’s headlight housing, giving it the desired stylistic touches.
Learn More: The Purpose of Low Beams and High Beams
Despite reflector housings still being more popular in most vehicles, they are gaining popularity and are used in many new vehicles. They are a little pricier than reflector housings, but they do a better job of focusing the light produced by the bulb, making it safer for both the driver and oncoming traffic. Additionally, the beam produced by the projector lens is more even than reflector housings can create.
Types of Headlights: Bulbs
Headlight bulbs are placed and held within the headlight housing, and even though the housings are responsible for helping disburse the light produced, the bulbs are responsible for producing the actual light.
There are three main measurements used for light bulbs: Lumens, Kelvin, and Lifespan.
Lumens are the measure of a light’s brightness, or more scientifically, output. Kelvin (K) is the measure of a bulb's color temperature – the higher the color temperature, the cooler and whiter in color a light appears. Lifespan is slightly different than lumens and Kelvin because it is not as scientific, but the expected light bulb lifespan is measured in hours.
Halogen headlight bulbs consist of a filament inside of an enclosed bulb that is sealed and filled with halogen gases. When turned on, the filament is heated up and glows. The halogen gases within the bulb help intensify the light produced and thus give off a bright enough light for nighttime driving and daytime visibility.
Halogen bulbs are usually the cheapest and simplest bulbs available. Because of this, they are also still the most widely used on vehicles, though they are slowly being replaced with brighter, more efficient, and more durable bulb types. They usually have the shortest lifespan of any bulb type and are most commonly found coupled with reflector or projector housings.
They also usually produce the lowest amount of lumens compared to other types of bulbs – around 1000 lumens for the average bulb – and lowest color temperature – normally between 2500 K and 40000 K.
High-Intensity Discharge or HID Headlights
High-Intensity Discharge headlight bulbs - sometimes called ARC or Xenon lights - function a little differently than halogen bulbs. Rather than a filament, they contain electrodes within a sealed bulb or housing between which electricity is passed. The bulb contains xenon gas and vaporized metals that help disburse the light produced by the passing of electricity between the electrodes.
HID lights are the next step up from halogen bulbs and are much brighter, much safer, more efficient, and more expensive. They are still not as commonly used as halogen bulbs, and many vehicle manufacturers are passing them over in favor of LED bulbs since they do not last as long and are not quite as efficient as LEDs. Still, they are much better alternatives to halogen bulbs and are most commonly used with projector headlight housings.
Typical HID headlights are rated between 3000 and 5000 lumens and come in various color temperatures ranging from about 3500 K to around 8000 K. Typical HID color temperature ranges from about 4500 K to 6000 K for normal road-going vehicles. This is what makes them safer at night and during the day as well as what gives them a cooler, blueish color compared to halogens.
Light Emitting Diode or LED Headlights
LED bulbs or light-emitting diode bulbs, are quickly replacing halogen bulbs and HID bulbs – to some extent – because of their efficiency, lifespan, brightness, and design advantages over other types of bulbs. They function by passing electricity through a diode, or a semiconductor, that produces photons, a process called electroluminescence.
As a result of their use of electricity and design, they are even more efficient than HID bulbs, which are already much more efficient than halogen bulbs. They are also very compact which allows them to be utilized for greater stylistic effects or in places that normal bulbs cannot be used. They are typically advertised to last for up to 50,000 hours.
Typical LED headlights fall close to the same parameters under which HID headlights fall without the shorter and less efficient disadvantages HID bulbs bring to the table. Normal LED headlights are usually rated at 4,000 lumens with a color temperature of around 6,000 K. They are usually used with either projector headlight housings or as strip lights that can also function as turn signals.
Learn More: HID vs LED Headlights
In theory, laser lights are the best possible headlights currently available on the market. They are most often offered only in the highest-end vehicles, mostly because they can cost well over $5,000. They function by using a laser that is projected into a housing that contains phosphorus. When the laser is turned on, a chemical reaction between the light and phosphorus occurs, producing the light you see.
Even though laser lights are even more efficient and can be many times brighter than LED lights, their use is limited because of their high cost, and the viability of putting them on most vehicles is quite low at this time. As a result, they are very uncommon and all but unavailable to be purchased as an aftermarket replacement for your standard headlights.
Headlights are an important part of your vehicle, not only for your nighttime vision but also for the sake of your vehicle’s visibility to others. Projector and reflector headlight housings are the main housing types. The main types of headlight bulbs fall under four main categories: halogen, HID, LED, and laser.
Each housing and bulb type come with their own set of pros and cons, and many types can be upgraded to provide the best lighting for your own wants and needs.