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Congratulations, you have defeated thousands of netizens to read this article and see the halogen lamp above. Let us have an in-depth understanding of the history of car lamps. Even those who are not old will never see halogen. Car headlights before lights. Forget about oil lamps, acetylene lamps, and incandescent lamps before halogen lamps, let’s start with halogen lamps.
Halogen lamp
Electric lights have been installed on cars since 1912, and it was not until 1962 that HELLA used halogen lights in cars for the first time. The light efficiency is 1.5 times higher than the previous lamp, and the lifespan is twice as long as before. Starting in 1973, halogen lamps began to be widely used in automobiles.
The luminous part of the halogen lamp is mainly composed of filament, halogen gas and glass shell.
The filament is made of tungsten filament, which is the same material as the filament of incandescent lamps used at home a long time ago. After being powered on, it emits heat and light.
Then at high temperatures, the tungsten filament will vaporize and sputter again. After consumption to a certain extent, the tungsten filament will eventually break. In order to alleviate this problem, high-pressure gas containing halogens (mainly iodine, bromine, etc.) is filled into the bulb. in. The main functions of halogen are twofold. ① The high-temperature filament causes tungsten to evaporate, but when encountering halogen gas, unstable halides will be formed. The halides are heated close to the filament and decompose, and the tungsten re-attaches to the filament, extending the life of the filament. . ② It allows the filament to withstand higher temperatures. Higher temperatures bring higher color temperature and higher brightness.
Xenon lights
Because the life of the halogen lamp was too short and the color temperature was not high enough, xenon lamps appeared and were quickly and widely adopted. It was also HELLA that introduced automotive lighting in 1987 and used it on the BMW flagship 750iL of that year.
The xenon lamp tube is filled with inert gases such as xenon and has no filament. Relying on high pressure to break down the gas, a stable luminous arc is formed between the two clicks. Therefore, it needs a driver (called a ballast, I don’t know why it has such a humanistic name. I prefer to use technical words to translate it literally, it is a Ballast or Driver).
When powered on, the driver outputs a high voltage of 23KV to instantly break down the lamp. Then the lamp voltage drops rapidly and finally stabilizes at around 85V.
Due to such a characteristic, it takes a few seconds for the xenon lamp to light up and stabilize its output, so it is not suitable for frequent switching. Low-beam headlights are a more suitable job for it. High-beam headlights that occasionally need to strobe are generally more suitable with halogen lights. Some models adopt the form of integrated high and low beams. In fact, the xenon lamps inside are always working. When high beams are needed, a baffle flips up at a speed visible to the naked eye.
Xenon lamps have high color temperature (4000K), high brightness and long life. But it takes a few seconds to stabilize, and the light pattern is not easy to adjust. Therefore, the market share is not as strong as that of halogen lamps. After 20 years of rapid development in the 1990s, they are almost not used in new cars this year.
Which xenon lamp is better? This still requires a higher level of equipment and technology, so currently, a certain brand of products from the Netherlands has the best quality in the industry, and not everyone can achieve the 1.5ppm level.
LED light
As a kind of light-emitting semiconductor material, LED has entered the automotive lighting industry after sweeping the civilian market. High color temperature, instant lighting, small size (convenient for optical and structural design) and other advantages allow it to quickly occupy the mid-to-high-end market.
In 1992, BMW was the first to use LED brake lights on its flagship 3 Series. After 2000, the Audi A8, the flagship car series, began to use LED daytime running lights. In 2008, Lexus began using LED headlights on the LS600h. Then things got out of hand. LED car lights were gradually decentralized from flagship car series to C-class or even B-class, and domestic brands used them on a large scale.
There are currently two mainstream forms of LED lights:
1. Use high-power automotive-grade LEDs to make L2 modules, and then combine them with thermal, mechanical, electronic, and optical designs to make small units and put them together into lamps. (The picture below is a schematic diagram, it does not mean that this Mercedes-Benz uses this LED)
2. Multi-beam form. It is used on the latest and most flagship models of Mercedes-Benz (Multi-beam), Porsche (Matrix system), and Audi (Matrix headlights).
Take Mercedes-Benz's Multi-Beam as an example. The right side of the picture is an array of small LED chips, and the left side is an optical lens. By controlling the brightness and darkness of each LED, precise light output is achieved. What should be illuminated is illuminated, and what should not be illuminated is dimmed.
As shown in the picture below, when a car or person is detected in the opposite direction, the corresponding area will darken. Not shaking the other person away also brings more security to yourself.
Laser headlights
This has been a hot topic in recent years. Since BMW first equipped its magical i8 model with laser headlights in 2014, the top models of flagship models of several major manufacturers have been equipped with laser headlights.
Laser headlights use laser diodes, which can be considered an upgraded product that is smaller than LED and has higher light efficiency.
The laser diode has a smaller emitting angle and higher light efficiency, so if people look directly at it, it will cause damage to the eyes. Therefore, even vehicles equipped with laser headlights do not light up whenever they want. The lighting conditions must be poor enough, the environment should be open enough, and there should be no people or other animals within close range. Therefore, it is conceivable that such an expensive thing is installed in a top-level car. Laobiu believes that even if it only has the lifespan of a halogen lamp, it will last until the car is scrapped.
Next development trends:
In the next few years, the trend of automotive lamp manufacturers should be "large-scale introduction of LED lamps", "strong rebound of halogen lamps", and "basically goodbye to xenon lamps".
So, for the majority of consumers who have bought cars equipped with halogen lamps and are dissatisfied with the halogen lamps that are yellow, not bright enough, and have a short lifespan, what should they do? At present, LED replacement car lights (LED Retrofit) are a better solution. Later, I will introduce some basic knowledge about LED replacement car lights.
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