The principle of halogen projector headlamps is to inject halogen gas such as iodine or bromine into the bulb, and at high temperature, the sublimated tungsten filament will chemically interact with the halogen, and after cooling, the tungsten will be re-consolidated on the tungsten filament to avoid premature breakage of the tungsten filament. halogen projector headlamps are easy to adjust and control the brightness, and have the advantage of good color rendering (Ra=100).