What we often refer to as "car headlights" can be understood in two ways. One interpretation is the broad sense of car headlights, which actually refers to the entire car assembly. The other interpretation is the main lighting source of a car, specifically, the bulb used for main lighting within the headlight assembly. The types of headlight bulbs are typically halogen and xenon lamps.

Headlight assembly

Halogen bulb，they are a type of incandescent lamp. The principle involves injecting halogen gas such as iodine or bromine into the bulb. At high temperatures, the sublimated tungsten filament reacts chemically with the halogen, and the sublimated tungsten re-solidifies on the tungsten filament, forming a balanced cycle that prevents premature fracture of the tungsten filament. Therefore, halogen bulbs have a longer lifespan than incandescent lamps.

Halogen bulb

According to design specifications, automotive headlamp assemblies are typically divided into separate high and low beam systems and integrated high and low beam systems. Most vehicles adopt a separate high and low beam lighting design, where the high and low beams are emitted by different bulbs within the same headlamp assembly. Usually, the lights near the outer side of the vehicle are low beams, while those near the grille are high beams.As shown in the figure:

To save space, most mini and compact cars typically adopt a dual-beam lighting design, where both high and low beams are emitted from a single bulb. This bulb features two filaments, allowing for the switching between high and low beams through circuit switching. Due to the high luminous flux of H4 bulbs, they are also widely used in some large SUVs. Halogen lamp models with dual beams include H4, H13, 9004, 9007, and H15, with H4 being the most widely used. Vehicles that adopt H4 as the main headlight illumination include the Nissan Tiida, Chevrolet Cruze, Fiat 500, and JEEP Wrangler.

H4Integrated high and low beam halogen bulb

Non-integrated halogen headlights, including H1, H3, H7, 9005, 9006, H8, H9, H10, H11, H12, H16, 9012, etc

Different vehicles, depending on their designs, use different types of headlights as low-beam or high-beam headlights. The same model may be used for low-beam headlights in some cars and also designed for high-beam headlights. Halogen headlights are of universal models, regardless of the vehicle model. That is to say, a sedan priced at 30,000 yuan may use the same model and brand of headlights as a vehicle priced at 600,000 yuan, whether for low-beam, high-beam, or fog lights. Nowadays, more and more high-end vehicles use xenon headlights as their main lighting system. Due to their energy efficiency, higher brightness, and longer lifespan, xenon headlights have gradually replaced halogen headlights in some mid-to-high-end vehicles.

Due to their high efficiency and low cost, halogen lamps remain the first choice for most vehicles. Integrating high technology into the design of halogen lamps, enhancing brightness and extending service life, while paying more attention to environmental protection, is the direction for the development of halogen lighting.