The overall design of the projector headlamp is to use a specially shaped reflector to focus the light and then use the shutter to project it onto the road surface. The pattern of the light beam is evenly distributed and tightly organized.

 Light Bulb: each headlamp requires a light bulb, and projector headlamps can use halogen, HID, and LED lights as light sources. The bulb of a projector headlamp can be much brighter than the bulb of a reflex headlamp. 

 Shutter: Shutter is one of the most important parts of the projector headlamp. It is not found in the classic reflector lens lampshade. The part is inserted into the beam from below, which causes a sharp cut and effectively directs the light towards the road rather than blinding the other driver. In some vehicles, the shutter can be raised or lowered to switch between high and low beams.

The halogen headlights are filled with halogen gas and have been in use since the 1970s to replace the incandescent bulbs. But it was replaced and surpassed by light-emitting diodes (LEDs) or high-intensity-discharge (HID) lamps in an automotive headlight. In Europe and Japan, there is a new headlight technology with “adaptive driving beams”, which can reduce the glare for oncoming drivers while providing high beam visibility everywhere. They are infinitely variable without using high and low beam. Before there is a great change, the insurance group suggest vehicle owners using the high beam as often as possible.

If we are replacing the headlight bulb to be LEDs, we don’t adjust the alignment screws but adjust the light beam by rotating the socket on the headlight bulb. LED and halogen bulbs both work with the reflector. But, the different reflector has a different inner structure. LED can’t emit lighting with a 360-degree angle like the halogen bulb. So, when we make it fit into different headlight reflector, we gotta adjust it to have a perfect light beam.