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Dipped Beam Shields

Dipped Beam Shields

Date posted: August 22, 2016 // Plansee

It is unlikely that many motorists who drive at night pay much attention to the mechanism that allows them to switch their headlights from their maximum reach to a downward angle that illuminates a much smaller area, which prevents any drivers approaching from the opposite direction from becoming dazzled. Introduced in 1915, the first vehicle headlights to be equipped with a dipped beam facility did not make use of the sophisticated, optical shield mechanisms used today. Instead, the vehicle relied upon a lever with which the driver was able to physically adjust the vertical angle of the entire headlamp within its mounting. Just under a decade later, the so-called Bilux bulb was the first to combine two filaments, one directed forward and the other angled downwards, within a single globe.

Subsequent refinements during the ‘30s saw the introduction of a globe with a third filament that provided an intermediate option between the full-beam and fully-dipped positions. Another interesting development that occurred at around the same time, and that is widely used today, was the directional lighting system that linked the orientation of headlights to the car’s steering, so that their beams could also move horizontally and thus follow the direction of the vehicle when turning.

Despite the early use of dipped beams, they did little to shield motorists from the high incidence of traffic accidents, with more than half occurring at night, even though night-time traffic was less than a quarter of that during the day. These findings have led to all manner of advances in the design of headlights and the related lighting technology. In practice, the bulk of these advances have tended to focus on improving the quality of illumination and include the use of Fresnel lenses together with the introduction of quartz-iodine lamps and, later, of energy-saving and rapidly-responding light emitting diodes. In addition, many cars are now supplied with two and some, even with three pairs of headlights as standard.

In parallel with the quest for improved illumination, there has also been a significant advance in the technology now used to operate dipped beam systems with the introduction of adjustable shields. The double filament bulb continues to be favoured by manufacturers and, in this system, the main filament is positioned at the focal point of a reflector, while the secondary filament is positioned just forward of that point. In this setup, all of the light from the main filament forms a concentrated beam that runs parallel to the principal axis.

By contrast, when the secondary filament is illuminated, because of its placement, the upper portion of its light will be out of focus, and will form a convergent mean that is directed downward while that from the lower half is prevented from reaching the reflector by the strategically placed shield, thus resulting in a very effective dipped beam.

In order to ensure that the resulting light cone remains as limited as possible, these items should be manufactured by experts such as Plansee. Plansee uses material that is resistant to tarnishing and corrosion, and the better quality units are therefore made from molybdenum. In addition to the many other quality components and materials supplied to manufacturers and end users in South Africa, LIT Africa is also a supplier of molybdenum dipped beam shields from Plansee.