Five steps to take you to understand headlights

Laser Headlights (2)

If you are just learning about modified headlights, are you confused when you are faced with various shapes of car headlights?Today, let’s take a look at the components of the headlights!


The car headlight housing is where the headlight bulb is housed. The shape of the Housing depends on the model of your car, so you’ll find that each headlight housing is different. The design of the shape of the lights also directly affects the layout between the bulbs. The headlight housing is generally made of PC (Polycarbonate). PC has excellent impact resistance and transparency, good mechanical properties and electrical insulation properties, a wide range of operating temperatures, high dimensional stability, and high creep resistance.

Two different types of headlight housing

High and Low Beams

The high and low beams are the core part of the headlights, both of which are used for night lighting. The high beams have a high light angle and a long distance, and the low beams are the opposite. Different high and low beams have differences in brightness and animation effects. From a technical point of view, the main differences between the high and low beams are the Reflector, Internal Structure, and the Light Source.

High and Low Beams Effect


The choice of the reflector has a great influence on the light output of the headlight. At present, car light manufacturers mainly use two different types of reflectors: Reflective Cup and Lenses.

Reflective Cup

Reflective Cup



What is the difference between the two?

 Reflective Cup

The reflective cup is a pure reflection light control.The secondary light spot is large. Most of the light is reflected through the cup surface, and the light shape is determined by the cup surface.Some light directly goes out without passing through the reflective cup, that is we call the secondary light spot.So,in general, the secondary light spot of the reflector will be larger than the lens.


Reflection technology and the interaction between media, the lens emits light from both physical and chemical reactions.From the effect point of view, the light spot has a transition from the middle to the outside, and the light control is better.The efficiency of the two is similar.But at the same angle, the lens has better light control. It should be noted that both have their own strengths, no good or bad, but different applications.

Reflective cup light shape

Reflective cup light shape

Lens light shape

Lens light shape

Internal structure

According to the internal structure, the headlights are divided into two types.One is the combination of high and low beams, and the other is the separation of high and low beams.The headlight with integrated high and low beams is mainly realized by the use of dual beam projector. Dual beam projector is mostly used in xenon headlights where the high and low beams share one light source. There is a light shield inside the lens. The high and low beams are realized by the up and down movement of the shading sheet.When the light shield is closed, it is low beam, and when the light shield is open, it is high beam. For headlights with separate high and low beams, different reflectors and light sources can be selected according to the design of high and low beams.

Two headlights with different internal structures

Two headlights with different internal structures

Light Source

Halogen Headlights

Generally, halogen headlights are most commonly used in family cars. Its manufacturing cost is low, the structure is simple, and it emits warm yellow light. The light is soft and uniform, so the penetrating power is stronger when the visibility is poor such as rain and fog. Therefore, halogen lights are also used in fog lights. However, halogen lights have limited brightness and limited illumination distance. During use, the heat is large, the efficiency is not high, and the service life is not long. It is worth mentioning that the halogen headlight with a lens for low beam is as shown in the picture, and the illumination effect is still good.

Xenon Headlights

Some old and high-end cars will be equipped with xenon headlights, with excellent illumination brightness. Because xenon headlights belong to gas light sources, there is no way to control the light shape with only the reflector bowl like halogen lights, and the original factory will be equipped with lenses.However, the xenon light is slow to light up, and the brightness is insufficient at the initial stage of turning on the light, and sometimes it even appears green.So it is not suitable for high beams with flickering function. Few manufacturers will use xenon lights to integrate the high and low beams.Usually, xenon lights are only used for low beams. When the high beams are always on, the light shield are opened in the lens to act as high beams. In addition, an additional halogen light is used as a flashing indicator.

LED headlights

Now the more popular headlights are LED headlights. The advantages of LED headlights are fast lighting, high brightness and low energy consumption. And due to the small size of the LED light-emitting unit, it can be used as a point light source.The disadvantage is that it is afraid of high temperature, the brightness will be attenuated after a long time of use.And the damage can usually only be replaced by the assembly, which is expensive.

Vland Tail Lights For BMW 5-s YAB-BW5-0376 (1)

Vland LED Tail lights For BMW5-s YAB-BW5-0376

From a macro perspective, there are two types of LED headlights. One is the relatively cheap reflective LED headlights. The PCB board on which the LED light beads are installed is located on the top of the light, and the light beads are downward. The size of the reflector bowl is small and one bowl corresponds to a group of light beads.The light type can also be more concentrated, but in order to prevent glare, the illumination height of the reflector headlights will generally be lower, such as the Accord, BMW 3 Series and Volkswagen Bora MQB. The paving effect and brightness of these headlights are better than those of traditional halogen headlights. But the biggest problem is that the low beam is difficult to illuminate, and the visual distance is limited. When the LED headlight is equipped with a lens, there is basically no short board, and because the LED light-emitting unit is small, it can realize various additional functions such as matrix projection.

Laser headlights

At present,the most advanced headlights should be laser headlights. Compared with LED headlights, laser headlights have a certain improvement in brightness, efficiency and volume, but the cost is too expensive. But the cost is too expensive, and a pair of laser headlights can easily cost thousands of dollars, so it is not widely used.

Laser Headlights

Side Marker Light

The side marker light is a light to better show the outline of the car. Some different countries have different requirements for side lights. For example, in China there is no mandatory requirement for side marker lights in headlights, while in the United States it is required that vehicles produced after 1970 must have side marker lights. At the same time, some countries require the side lights to glow yellow. There are two solutions for such a requirement, one is a yellow bulb with a clear reflector, and the other is a yellow reflector with a white light.


The daytime running lights(DRL) are set up to indicate the presence of the vehicle ahead during the day, and are installed on both sides of the front end.The purpose of DRL is to make the vehicle more recognizable when driving during the day. Its function is not to enable the driver to see the road, but to let others know that a car is coming. Therefore, this kind of light is not a lighting light, but a signal light.

In short, the purpose of DRL is for traffic safety. Therefore, in recent years, many countries have formulated relevant indicators for daytime running lights to ensure that the DRL produced and installed can really play a role in ensuring safety. The most representative of them is ECER79 in the ECE Automotive Technical Regulations of the Economic Commission for Europe. However, some low-profile lights do not have the function of daytime running lights, and you can obtain the function of daytime running lights by purchasing high-profile replacement lights.

Turn signal

Turn signal is an important indicator light that is turned on when the motor vehicle is turning to remind the front and rear, left and right vehicles and pedestrians to pay attention. The turn signal generally adopts halogen light source, single-chip control circuit, left and right alternating stroboscopic and uninterrupted work. The turn signal adopts a flasher to realize the flashing of the light. The vast majority of cars in the world have yellow turn signals. This is mainly because the yellow light has the strongest penetrating power, and in the case of low visibility such as foggy, rainy and snowy weather, it is still possible to clearly see the direction of the vehicle ahead to ensure driving safety.

However, there are very few countries that allow the turn signals to be of other colors. For example, the turn signals of some models in the United States are red. Therefore, be sure to pay attention to the regulations in your region or country when modifying your lights. In recent years, some car light manufacturers have designed streamer effect on the basis of turn signals. Using high-brightness LED light beads, the streamer follows the direction lights, bringing a unique streamer show.

After reading the above introduction, you must have a certain understanding of headlights. But it needs to be emphasized that the modification of lights involves driving safety and automotive circuits. If the modification is improper, it will have a negative impact on the driving safety of others and yourself. Safety must be considered as the primary factor when constructing and purchasing components. If you have any questions or ideas, please leave a message below.

Back to list

Related Posts

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.