Headlights have been an integral component of automobiles ever since their introduction in the early 1900's. They were originally developed to offset the high fatality rate of night time drivers. The U.S. National Highway Traffic Safety Administration stated that, "Nearly half of all traffic-related fatalities occur in the dark, despite only 25% of traffic travelling during darkness."Have you ever wondered why there are so many different types and styles of headlights? Advances in technology, ever changing demographic trends, and varying safety standards have spurred the transformation of the once elementary and simplistic headlight design into a plethora of different shapes, designs, and styles.
With over 200 million motor vehicles on U.S. roadways everyday, chances are, you've seen just how different headlights can be.
Today, headlight construction is based on one of two main standards; The ECE or the SAE. The distinction among the two standards is based upon three main criterions.
1. The extent of allowable glare on other drivers
2. The least amount of light emanating down a straight away
3. The precise location and light levels of emanating beams
The ECE is widely accepted by nearly every industrialized country outside of the United States. The SAE is unique in that it is the only standard that is mandatory in the United States and no where else.
U.S. automotive lighting manufacturers began to focus on the strategy of balancing low power and efficient light, where as Europe manufacturers focused mainly on performance and maximum output. Due to the difference in safety standards and performance goals, the distinguished styling of headlights produced by the U.S. and countries outside of the U.S. vary heavily in design and features.
So what specifically affects the performance of a headlight? There are two main factors responsible for lighting.
1. The optical systems which direct the light towards a focal point.
2. The light source itself that is actually emanating the light.
Today, there are two main types of optical systems used on automobiles. The first is known as a reflector lamp. These lamps use optics to direct reflected light. There are two main types of optics used in reflector lamps.
1. Lens optics - refracts light through a lens at the front of the headlight into a desired pattern.
2. Reflector optics - disperses light in a pattern designed into the reflector itself, rather than into the lens.
The second type of optical system common to automobiles is known as a projector lamp. This system concentrates reflected light into a focal point aimed through a condenser.
Beyond optical systems, the light source itself is the other major factor responsible for lighting. The original light source used for automobile headlights was ignited Tungsten gas in a sealed vacuum. These headlights are virtually obsolete due to their lack of efficiency.
The addition of halogen (quartz-iodine) technology with Tungsten created more light using less power.
The next advancement in lighting uses metal halide lamps that contain xenon gas. This method was dubbed as a high intensity discharge or HID. Introduced in the early 1990's by BMW, HID's had a much higher adoption rate in Europe and Japan than North America.
HID's have been praised for many benefits over halogen lamps. These reasons include:
1. Less power consumption with higher luminosity
2. Longevity
3. Increased Safety
The newest advance in automotive lighting was the use of LED technology. Advantages of LED's include lower power consumption, longer life spans and more flexible design possibilities. The 2009 Cadillac Escalade Platinum was the first all-LED headlamps sold in the U.S. market. LED headlights are still currently improving and are aspiring to be the new premium headlight.
In conclusion, there are many technical aspects that can affect the lighting of an automobile. Beyond optics and light sources, the dynamic control of headlights can drastically improve a vehicles performance. Also normal care and cleaning is a small detail that can drastically affect your headlights visibility. With continuous breakthroughs in technology, headlights will only bring us closer to a safer road.
