Since the dawn of the automobile, manufacturers have been striving to improve nighttime visibility by adding lighting to vehicles. The earliest versions of vehicle headlights used in the late 19th and early 20th century were usually powered by kerosene or acetylene. As vehicle electrical systems became common place, automotive lighting technology moved to electrical lighting. The first electric headlamps used in automobiles appeared in the early 1900’s and became commonplace by the 1920’s.
These early headlamps used a tungsten filament bulb, while this provided many advantages over the early gas lanterns, tungsten bulbs had a relatively short service life and a low light output. The light output was further decreased over the life of the bulb due to darkening of the glass caused by particles of the vaporized tungsten filament coating the inner surface of the bulb. This problem was corrected in the early 1960’s with the development in Europe of the Halogen bulb. Halogen automotive bulbs solved many of the problems with traditional tungsten incandescent bulbs but had some drawbacks. Halogen bulbs still have a limited service life and are susceptibleto failures caused by vibration and impact. They are also not very energy efficient and generate high temperatures.
Through the 1980’s and 1990’s, European companies such as Hella, Bosch and Valeo, continued to push the boundaries in lighting technology and design. First, through improvements in engineering and materials, new lens and reflector technologies were developed to improve performance of halogen light sources. In 1983 Hella introduced the first mass-produced projector beam, know as a “DE Projection Headlamp” developed for BMW. Other innovations included the introduction of reflector-based optics to create the light pattern, which feature optical elements included in the reflector rather than the lens as was previously required. This development significantly changed the look of modern headlights. Clear headlight lenses are taken for granted now but when they were introduced in the 80’s the look was revolutionary.
The first major leap in automotive lighting technology since the Halogen bulb occurred in 1992, with the introduction of the first-generation Xenon High Intensity Discharge (HID) headlamps, again developed by Hella for BMW. HID lamps offered numerous benefits over incandescent light sources including a greatly increased light output and color temperature much closer to daylight, while at the same time using less energy and producing less heat. Additionally, because HID lamps do not have a filament like traditional bulbs, the service life is typically 2500+ hours of operation, compared to 500 hours or less for incandescent bulbs. The main drawback to HID lamps has always been the increased cost of the technology compared to traditional incandescent light sources.
While HID technology is still in use, in the last 10 years it has been surpassed by light-emitting diodes (LEDs). LED is generally thought of as a recent development, but LEDs have been around for years, in fact the first use as a vehicle light was in 1992 as a third brake light. Since then LEDs have been improving in efficiency, performance and output and the automotive market has seen explosion of use for both interior and exterior vehicle lighting. LEDs have allowed automotive lights to be designed in sizes and shapes never before possible, all while consuming significantly less power than other lighting sources. As the technology improved, the early 2000’s saw the first LED headlamps being offered in standard production vehicles. The first all-LED headlamp in the US, manufactured by Hella, was offered beginning in 2009 on the Cadillac Escalade. In the time since, LED headlamps have become standard on a wide range of vehicles from European luxury sedans to pickup trucks to economy cars.
The future will certainly bring many more exciting innovations. Developments on the next generation of automotive lighting continues to be led by European companies. Designs which will most likely play a significant role in the future of automotive lighting include new light sources such as lasers, which are already being explored. In addition to light output, improvements to the way light is controlled are ongoing as well. Though the use of fiber optics and other technologies, manufacturers can reduce or eliminate glare and allow the light to turn to follow the path of the vehicle or even where the driver is looking. The history of automotive lighting has paved the way for a truly bright future.