Automobiles are equipped with both low-beam and high-beam outputs from their headlights. The low-beam output is usually angled downward and slightly away from oncoming traffic, in order to reduce glare for oncoming vehicles on the opposite side of the road. The high-beam output is brighter and lacks the directional requirements of the low-beam output, and as such is suitable only when alone on the road. Because of the different angular requirements of the low-beam and high-beam outputs, switching between low and high beams is not as straightforward as making the headlamp brighter or dimmer.
For many years, until the mid-1980s, automobiles were typically equipped with separate headlamps for the low-beam and high-beam outputs. The low-beam and high-beam headlamps were mounted adjacent to each other on the front of vehicles, and were aimed appropriately to meet the angular requirements of the low and high beams.
For a variety of reasons, it is desirable to have a single headlamp produce both low-beam and high-beam outputs.
One example of a single headlamp that produces both low-beam and high-beam outputs is known as a projector lamp. Essentially, the typical configuration for the projector headlamp uses a shield or light baffle that is movable by a solenoid or other actuator. For low beams, the shield is in place, deliberately blocking a portion of the lamp output in order to achieve the desired angular output. For high beams, the shield is moved out of the way and uncovers the brightest part of the beam.
One potential drawback of this known configuration of projector lamp is that includes moving parts, which are more prone to failure than comparable stationary parts.
Accordingly, it would be advantageous to have a configuration of projection headlamp that produces both low-beam and high-beam outputs but lacks moving parts.
Other headlamps are known in U.S. Pat. No. 7,563,008 (Chinniah, et al.); U.S. Pat. No. 7,134,774 (Iwasaki) and U.S. Pat. No. 7,178,957 (Schug, et al.).