On a foggy morning, poor visibility makes drivers nervous. In the fog, it is vital to secure visibility and, at the same time, let other cars know about your presence. Fog lights, which used to be easily seen on the front bumper, are gradually disappearing in recent years. Is it because we are getting less fog, and more sunlight? In fact, this has a lot to do with the development of headlamp technology.
Korea, which belongs to the dry climate zone, does not have frequent fog. According to the Korea Meteorological Administration, fog occurs about 10 times a year in Seoul. According to the statistics of traffic accidents by weather conditions published by the Road Traffic Authority, the frequency of fog itself is low, so the number of related traffic accidents is the lowest; However, accidents caused by fog cannot be overlooked. The number of casualties per accident, which can determine the severity of accidents, is the highest on foggy days.
Fog lights are installed to alert other drivers in fog, which can sometimes be fatal. Although it is not a mandatory equipment, the Ministry of Land, Infrastructure, and Transport in Korea has enacted related laws and regulations in detail such as the number, location, brightness level, and irradiation direction of fog lights so that they do not obstruct the view of other drivers. For example, vehicles weighing less than 3.5 tons must have fog lights installed at the height of 25 cm or more and 80 cm or less above the ground. And the brightness should be between 940 candelas (cd) and 10,000 cd, which is lower than the minimum brightness of the headlight. (Reference: The Korea Motor Vehicle Safety Standards Act 38‒2)
In the past, when halogen lamps were mainly used, it was difficult to secure sufficient visibility in fog with only the headlights. The fog lamp was a device to compensate for the shortcomings of the halogen lamp, which lacked the straightness of light. Light from fog lamps with a low color temperature has a relatively long wavelength, so it has less refraction in wet conditions such as rain or fog. In other words, the vehicle is clearly visible in the fog. Fog lamps also spread the light widely with convex lenses, so it secures visibility at the lower part of the vehicle where the headlights can’t reach, and it also helps to identify lanes.
Recently, the advantages of fog lights have not been highlighted, except for a few situations where visibility near the underside of the vehicle is insufficient due to the unusually high headlamps. In fact, less than half of the cars currently on the market in Korea are equipped with fog lights. The stereotype that ‘fog lights are essential equipment’ has changed with the passage of time.
Even before the 2000s, a lens‒type headlamp with an optical pattern to refract light on a translucent headlamp cover was common. However, recently, MFR (Multi Face Reflector) headlamps using clear covers and reflectors and projection headlamps based on refractive lenses are mainly used. By using these two methods, it became possible to form a beam pattern more precisely while improving the amount of light of the lamp.
This technological change is starting to reduce the need for fog lights to ensure visibility. In addition, the LED (Light Emitting Diode) light source, which boasts excellent visibility with much less power than the existing light source, stimulated this further.
LED headlamps, which were created following halogen and HID (High‒Intensity Discharge), have a strong advantage in that they can achieve maximum visibility within regulations by composing multiple LED units according to vehicle characteristics and design. Moreover, the short‒wavelength, near‒white‒blue light source of the LED boasts high straightness and quick response. In other words, since the headlamp alone has sufficient all‒weather visibility performance, a device that assists the headlamp, such as a fog lamp, is no longer needed.
LED lamps are rapidly expanding the range of applications based on energy efficiency that is 20 times greater than that of halogen lamps. Of course, HID, which was spotlighted as a next‒generation light source before LED, also has a field of view that is comparable to LED headlamps. However, LED not only has the advantages of HID light sources, but also has a much higher degree of freedom in design, configuration, and design of the headlamp thanks to the compact lamp unit structure.
As the main axis of the vehicle light source is shifted to LED, fog lights are expected to be more difficult to find on the road. This hypothesis is supported by the fact that there is not a single model equipped with fog lights among Hyundai Motor Group’s Genesis brand models, as well as most of the global premium auto brands.
With the disappearance of halogen lamp‒based fog lights, significant changes have taken place throughout the auto industry. These changes are closely related to the core characteristics of LED light sources. For example, the power consumption of the car is reduced, and the weight is also reduced slightly. The biggest change is the increased level of freedom in the design of the front part of the vehicle, including the front bumper. In addition to realizing a more beautiful design, it is also evolving in a functional direction, such as actively utilizing elements for aerodynamic performance such as air curtains.
In addition to a dramatic improvement in luminous performance and miniaturization of the lamp unit, linkage with electronic systems including sensors becomes free, and headlamp technology is entering a new era. In particular, in recent years, as individual units of numerous LEDs can be controlled, a technology for real‒time illumination change is in the spotlight.
A typical example is the Intelligent Front‒lighting System (IFS), which is installed in most models of the Genesis brand. This technology combines the adaptive headlamp function of the past with the active headlamp function represented by Hight Beam Assist. IFS, which renders the fog lights that assist the headlights useless, maximizes lamp performance in dark areas where visibility is required, while minimizing the impact on other vehicles’ visibility. It provides optimal visibility performance regardless of the weather conditions, day or night.
New technology complements and sometimes replaces old technology. It’s not just the fog lights that are disappearing with the evolution of headlamp technology. In the transition to the future mobility era, the latest automobiles are rapidly changing the paradigm of convenience and safety equipment that was once considered essential just a few years ago. The story is the same for the Digital Side Mirror (DSM) housed by the IONIQ 5 for the first time in Hyundai Motor Group. Like the fog lights that influenced the design of automobiles and even caused functional changes, DSM not only completes the sleek design of the car, but also provides better side and rear visibility than conventional side mirrors in the rain or at night.
It may be just a matter of time before camera‒based devices like the DSM completely replace side mirrors. After so many changes, we are now facing a car full of advanced technology. Like LED headlamps that cover the role of fog lights based on excellent performance, the replacement by technology will be repeated constantly.
HMG Journal Operation Teamgroup@hyundai.com
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