The lamp is the "eye" of a car and one of the essential safety configurations for driving at night. Throughout the history of automobile development, the evolution of lamp is also called an "evolutionary history". From the most original kerosene lamp to today's laser headlights, technological advances have also greatly improved the lighting of cars. So, what types of car headlights are there on earth? What are their characteristics and advantages?
1. Classification by light source
Halogen headlamps, also known as tungsten halogen headlamps, are a variant of incandescent lamps and are widely used in automotive lighting. The principle is to use a resistor with a current to heat up and emit black body radiation with a wavelength in the visible band when the temperature is high enough. However, halogen headlights are increasingly unable to meet the current lighting needs because of their dim and yellowish light and small illumination range. They are even teased as "candle lights" by netizens. However, halogen lamps are used in many inexpensive cars because of their low cost and easy maintenance and replacement.
Xenon headlamp is a kind of gas discharge lamp, which uses a matching electronic ballast to instantly raise the 12V voltage of the accumulator to above 23V. After triggering the voltage, the high voltage pulsed electric current excites Xenon, a small amount of mercury vapor, metal halogen and other substances in the fully enclosed micro-quartz lamp, and generates light in the arc by ionizing them. Xenon headlamps have two distinct advantages over halogen bulbs. One is that Xenon bulbs have three times more light intensity than halogen bulbs and consume only two-thirds of their energy. The second is that Xenon headlights use light colors similar to those of the sun to create better visual conditions for drivers. However, in foggy weather, the penetration of xenon headlights is slightly less than that of yellow halogen headlights.
LED light, also known as light-emitting diode, is an important component of vehicle taillights, high brake lights and daytime traffic lights today. Some vehicles also use LED light source on their headlights. LED lamps have many advantages, high luminous efficiency, energy consumption is only 1/20 of halogen lamp, but life span is up to 100,000 hours, in the design life of the car, there is little need to replace. In addition, the small size of the LED light group makes it easy to arrange and shape the vehicle. Of course, the high cost is also a big obstacle to its popularity.
* Laser headlights
After LED headlights, laser headlights are called the "reasonable next step" because they are more focused, energy efficient and have a longer life than LED headlights. The principle of a laser headlamp is that a blue light from a laser light-emitting diode will run through the fluorescent phosphor material inside the headlamp unit, converting it into a diffused white light, which is brighter and more eye-friendly. For automobile headlights, long illumination distance, small light divergence, low energy consumption and long life are the ideal lamp, while laser headlights are the light source that combines the above advantages in current artificial light sources. The only disadvantage is that it is too expensive.
2. Classification by scientific and technological nature
Follow turn headlights
Auto Headlight (AFS), also known as Auto Headlight, is a light technology that dynamically adjusts the lights to the current turning angle according to the steering wheel angle, vehicle deflection rate and driving speed, and keeps the direction of the lights in line with the current driving direction of the car to ensure the best lighting for the road ahead and to provide the best visibility for drivers. This significantly improves the safety of driving in the dark. In poorly lit or multi-curve road conditions, expand the driver's view and alert each other to come in advance.
Active High Beam technology is a relatively new car lamp system at present. The main light sources are HID (xenon), LED (light emitting diode) and laser headlight. The principle is to use two optical cameras located in the headlight and front windscreen to scan the vehicles and pedestrians running on the front road. When the optical camera scans the road with front cars or objects coming, the baffle in the headlight group will automatically block the light of the corresponding area in the headlight group according to the width of the front car or the opposite car, and the camera will continuously scan the distance between the car and the front car and the incoming car. Constantly control the position and area of the baffle to reduce the interference between the light on the front car and the driver's line of sight by blocking the light until the front car or the opposite car exceeds the driver's line of sight.
Pixel headlamp is based on LED headlamp source. DMD chip is the core component. Digital light technology (DLP) and intelligent recognition control algorithm are combined to realize digitization and intelligent operation to control the headlamp system with accuracy up to megapixel level. Pixel headlights can directly project text, graphics and even play video images to the ground, so as to communicate with vehicles and pedestrians, warning, and greatly improve the safety of driving.
3. Classify by Style
- Hidden headlights
Hidden headlights are also called flip headlights, or jump lights. This design has been used by many classic models, the well-known AE86, the official masterpiece of hidden headlights. The structure of this headlamp is very clever. When not in use, it can flip back to a smooth surface and blend with the body, reducing air resistance to maintain a complete shape and improve fuel economy. However, hidden headlights also have many defects, such as high failure rate of the rotating device, the headlights can not be raised, which affects driving safety; When a traffic accident occurs, vertical headlights can cause secondary injuries to the victims, and so on. Ultimately, hidden headlights are prohibited. Today's vehicles can no longer see this design of headlights.
Lens headlights actually refer to a way of focusing light. A traditional headlight is a bulb with a shining shade (spotlight cup) behind it, similar to the principle of a torch. A lens headlamp uses a smaller, compact spotlight cup to focus the light into a parallel beam and then fans through a convex lens, which is bright and clear.
Matrix headlights are a lighting system consisting of multiple LED lights, cameras and sensors. Besides adjusting the direction of illumination ahead of time when the car turns, they can also automatically flash to remind pedestrians to avoid when there are pedestrians in front at night. In addition, the matrix headlamp will automatically turn off part of the LED light which responds according to the position of the other party to avoid the impact on the other party's vehicle.
* Roof headlights
Roof headlights are usually less common and are often used as auxiliary lighting in off-road vehicles and engineering vehicles. These types of vehicles have special applicable scenarios. When crossing the Gobi Desert, cross-country vehicles are often sparsely populated and have complex road conditions. The original lamp has limited light intensity and illumination range, so it is necessary to use the roof lamp to expand the illumination range and ensure driving safety. The same is true for engineering vehicles. During construction operation, the roof lamp is also needed to increase the intensity of illumination to ensure the safety of construction operation.