Abstract: This paper introduces the application status of automotive light source, and focuses on the characteristics, application and development of thermal radiation automotive light source and gas discharge automotive light source. At the same time, it briefly introduces other types of automotive light sources, and forecasts the development trend of automotive lighting. Keywords: automotive lighting; light source; lamps; heat radiation; gas discharge; light effect Introduction Lighting is indispensable when driving a car. The main functions of automotive lamps have two points: one is the lighting function, that is, illuminating roads, traffic signs, pedestrians, other vehicles, etc., to identify signs and obstacles; the second is the signal function, which shows the presence of the vehicle and conveys the driving state of the vehicle. signal of. Automotive lighting and signaling devices are important safety components for automobiles. Of the 105 European ECE regulations for cars, 36 are directly related to automotive lighting and signal lights. Among various automobile lights, the role of the headlights is particularly important, and has a very close relationship with driving safety. Relevant statistics show that the probability of traffic accidents at night is greater than that during daytime driving, which is very directly related to poor lighting conditions at night. With the development of the automotive industry and the improvement of driving speed, the quality of automotive lighting is receiving more and more attention. The car light source is the light-emitting component of the car lamp, which is the core of it. Therefore, selecting the appropriate car light source to improve the quality and efficiency of the car light source plays an important role in improving the quality of the car lighting and increasing the driving safety. The use of lighting devices in cars began around the beginning of the 20th century. The first to use kerosene lamps and acetylene lamps, and then began to use electric light sources, experienced the development process from vacuum incandescent lamps, inflatable incandescent lamps, tungsten halogen lamps to gas discharge lamps. With the development of the light source industry, automotive light sources are constantly being updated to meet the ever-increasing requirements of automotive lighting. The car headlights must illuminate the road surface and traffic signals in front of the car, and can not cause uncomfortable glare to the driver of the car. This requires that the spatial intensity distribution of the headlamps meets very precise requirements. In China, the light distribution standard for automotive headlamps is equivalent to the relevant European ECE regulations. The light distribution of the low beam headlamps is completely asymmetrical. In the middle is a high light intensity area to illuminate the road ahead as much as possible. The beam is spread out in the horizontal direction to facilitate the identification of the roadside conditions. The light intensity is small in the direction of the driver's eyes pointing to the other party, and no glare is generated. There is a very clear dividing line between the light and dark areas produced by the headlights, called the light intensity cut-off line. Because the regulations have very strict requirements on automotive lighting, compared with ordinary light sources, automotive light sources have some special features in structure and performance, thus forming an independent series of automotive light sources. In order to facilitate the design of lamps, many automotive light sources have been standardized internationally. 1. Incandescent lamps and halogen lamps The first electric light source used in automotive light sources is incandescent lamps. After decades of development, the performance of incandescent lamps has been greatly improved, and tungsten halogen lamps have been developed on the basis of incandescent lamps. Incandescent lamps and tungsten halogen lamps are currently the main automotive light sources, and are widely used in lighting and signaling devices inside and outside automobiles. Both incandescent lamps and tungsten halogen lamps are heat radiation sources. When the filament passes current, the temperature rises due to the thermal effect of the current, and becomes incandescent, thereby emitting visible light. The characteristics of this kind of light source are that the driving circuit is simple, the price is cheap, the size of the illuminating filament is small and the illuminating is stable, which is beneficial to the optical design of the luminaire system. Compared with incandescent lamps, tungsten halogen lamps are characterized by small size, high power, high luminous efficiency and compact filament. They are ideal automotive light sources. Incandescent lamps have low power and are mainly used in applications where the control requirements are not very high. For example, S25 (21/5W) and T20 (21/5W) can be used for taillights/brake lights, S25 (21W) and T20 (21W). For turn signals and reversing lights, T10 (5W) can be used for taillights and license plate lights, and T10 (10W) can be used for interior lights and door lights. Tungsten halogen lamps are more powerful and are often used for lighting in front of vehicles. For example, H3 (55W) can be used for front fog lamps, while tungsten halogen lamps for headlamps are available in many varieties, including H4 (60/55W), H1 (55W). ), H7 (58W), HB 1 (65/45 W), HB3 (65W), HB4 (55W), and the like. Incandescent and tungsten halogen lamps are constantly evolving. Incandescent lamps are widely used in car signal lights. Due to the strict requirements of various regulations on the color of various signal lights, such as taillights and brake lights are red, and the turn signals are for the color of the market. Therefore, the current signal lights usually use colored blister or color. Light microscopy. Nowadays, customers are increasingly demanding the appearance of the car. Many car lamps use a colorless transparent patternless light-viewing mirror, which can directly see the inside of the lamp. If the incandescent lamp with colored bulbs is used, it will not be used during the day. When the appearance of the lights is not satisfactory, people call it the "fried egg effect." In order to improve the appearance of the lamp, in recent years, a technique of plating a multi-layer dielectric interference film on a colorless and transparent blister has been developed. When the signal bulb is not ignited, the outer casing is silver-white, compared with the color of the reflector background. Coordination, the light emitted when igniting is in the market, which greatly improves the appearance quality of the lamp. As the main automotive light source, tungsten halogen lamps have several development trends. The first is to adapt to the development of automotive lighting. With the advent of free-form reflectors, the corresponding light source such as H7 is also available. The second is to improve the structure of the light source, especially the structure of the lamp head, so that the light source is positioned more accurately and easily within the lamp. H8, H9, HI are representative of new halogen tungsten automotive light sources, H8 is used for front fog lamps, H9 is used for high beam headlights, and H11 is used for low beam headlights. Their common feature is that they have a special design. The plastic metal combination lamp head is very convenient to install in the luminaire and has precise positioning. It is worth mentioning that the life of the H11 lamp exceeds 2000 hours. The third is the use of shell coating technology. In order to improve the luminous efficiency of the light source, an infrared reflective film may be plated on the bulb to reflect the infrared radiation of the filament back to the filament, thereby increasing the temperature of the filament and reducing energy consumption. Some customers like the color of the headlights to be blue, so the visual sense is very white, bright, and the light color is closer to daylight, which improves the comfort of driving. These customers can request the blue film on the bulb. achieve.
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