LED has the advantages of energy conservation and long lifespan, and has been widely used in various small lights inside cars. With the introduction of high brightness LED, various external car lights have also begun to use LED. This article will introduce the development history of automotive headlights and the LED automotive headlight solution launched by Arrow.
Gradually evolving automotive headlight design
Since the birth of automobiles, kerosene lamps (1886-1904) were initially used for lighting purposes. The design of car headlights can be said to be better than nothing, and the so-called headlights simply hang kerosene lamps on the car, which can be said to have no function. With the changing times, due to the low luminous power of kerosene lamps, they were quickly replaced by acetylene lamps (1905-1925). With the development of electric lights and the improvement of bulb durability, acetylene lamps, along with their defects, have gradually withdrawn from the stage of the history of car lights and replaced them with increasingly mature incandescent lamps.
However, the luminous power of incandescent lamps is generally not high, so more energy-efficient halogen lamps have emerged and gradually become the mainstream of automotive headlights. However, in response to the drawbacks of low brightness, high electricity consumption, and short lifespan of the incandescent lamp series, in the 1990s, professional lamp manufacturer Haila pushed higher brightness xenon lamps to the market. Xenon lamps improved Edison's invention of tungsten filament luminescence principle, filling quartz tubes with high-pressure inert gas to replace traditional filaments, making xenon lamps the preferred choice for high brightness automotive headlights.
Following the xenon headlights, there are currently LED car headlights that have not been widely used. Although they have been seen in many concept cars before, due to technology, cost, and regulations, the application of LED headlights in cars has only been in recent years.
The advantages of LED car headlights
The car headlights currently in practical application mainly include halogen lamps, xenon lamps, and emerging LED lamps. Among them, halogen lamps have the disadvantages of low luminous efficiency and high heat generation, and their brightness is relatively low. They are generally low-end standard equipment in cars, so it is difficult to meet the needs of drivers nowadays. On the other hand, the lifespan of halogen lamps is relatively short. Under normal circumstances, the longest lifespan of a halogen bulb can last about 1000 hours. In addition, the appearance of halogen lamps is rigid and can only be made into double circular lamps, which limits the shape of the lamp.
High brightness xenon headlights are currently the mainstream headlights used in high-end car models. However, xenon headlights have poor focusing ability and are too bright, which can easily shake the driver of the opposite vehicle and cause accidents. Moreover, their light penetration is poor, and their penetration is very weak in foggy and snowy weather. Another fatal flaw is the delay effect of xenon headlights, which is due to the working principle of xenon headlights. It takes 2-4 seconds to light up, and when the vehicle is driving at high speed, the horn is often not used, so the headlights need to be used to "shake" the vehicle in front. However, relying on xenon headlights will be ineffective.
The emerging LED lights have the advantage of very high luminous efficiency. LED lights directly convert electrical energy into light energy through LED, so LED lights are also known as cold light sources. The working temperature is generally 50 to 70 ℃, and the power consumption is only about 1/10 compared to ordinary car light bulbs. Therefore, they can better save fuel consumption and protect car circuits from being burned out by excessive load currents. In addition, LED is similar in brightness to xenon lamps, and its energy-saving performance is stable and relatively environmentally friendly. Its spectrum of light does not contain ultraviolet and infrared rays, and the headlights are combined through multiple LEDs. Therefore, the design can be freely matched, and can be shaped into a cool shape, which is very beautiful. In addition, its lifespan is very long, can reach 50000 hours, and it has a wide color temperature space, which can be achieved from high color temperature to fog lights. Its high-speed reaction speed makes it the most promising automotive headlight technology at present.
Dim vision at night is the main cause of car accidents
Car lights can be said to be one of the most important equipment in cars, as accidents caused by incorrect use of car lights account for about 40% of all accidents. According to incomplete statistics, about 60% of global traffic accidents occur at night. In 2013, the number of deaths in nighttime driving accidents in China was 50000, accounting for about 50% of the total number of traffic accidents. Among them, from 7 pm to 6 am the next day, more than half of the total number of deaths occurred, indicating that poor visibility at night is the main cause of traffic accidents.
There are so many traffic accidents caused by vehicles at night. In addition to excluding human factors that contribute to poor driving, it is necessary to mention the impact of car lighting on safe driving. About 22% of traffic accidents occur in situations with poor visibility. Many accidents are caused by the limited width and distance of vehicle lighting, dim lighting colors, and drivers cannot see obstacles in the road clearly while driving, which leads to accidents. Therefore, the use of high brightness and adaptive driving beam (ADB) LED matrix headlights that can automatically change light types in conjunction with road conditions has become a new trend in the development of car headlights.
Adaptive car headlights with intelligent lighting function
ADB adaptive car headlights are an intelligent high beam control system that can adaptively change the shape of the high beam according to road conditions. It transforms a complete high beam spot into a high beam spot composed of multiple optical lighting zones through special optical modules and electronic control. When vehicles, pedestrians, and other targets appear on the road, the control system composed of sensors (cameras) and driving circuits will turn off or dim some of the high beam lighting zones, thereby avoiding glare to the illuminated targets and ensuring clear high beam lighting.
In addition, the ADB system can automatically turn on or off the high beam for the driver based on the driving status, environmental status, and road vehicle status of the car. It can also be paired with the control system inside the vehicle. When the car turns, it can self adjust and change the direction of the light, making light control more convenient and comfortable. It can even set various light modes, such as urban mode, rural road mode, highway mode, curve mode, etc., to meet more complex road conditions.
epilogue
The emerging ADB matrix LED car headlights can be said to be the best choice for car headlights at present, which can improve the overall safety of the car, provide more flexibility in car design, enhance the sense of technology and value of the car. Currently, many car manufacturers have applied them in commercial car models. As the market size of LED car headlights gradually expands, their costs are expected to be further reduced and will gradually be popularized in more car models, forming a positive market cycle, and the market prospects will be extremely promising.
