The projector is a major part of HUD as it projects the information on a transparent windshield. In early HUDs, refraction was used for projecting images in the projector, whereas in modern HUDs, reflection is used to project the image. Projection units use cathode ray tubes, LEDs, or liquid crystal displays to project the image. Projection units can be adjusted either below or above combiners. Projector projects image through the laser beam. Projector units are expected to lead the overall head-up display market.