In 1885, a German engineer Karl Benz (. Karl Benz) developed the world's first three rounds of internal combustion engine powered engine, it is made of metal materials, the car was born and developed rapidly. However, in order to drive at night or on dark roads, there must be lighting tools. It can be said that with the automobile, there will be the headlights. The evolution of the headlamps generally goes through the following stages:
1. The first kerosene lamp was a kerosene lamp installed in a car. However, the luminous intensity of kerosene lamp is too low to meet the requirement of lighting up the car far enough. To improve the illumination of the road ahead, a paraboloid reflector strip with a chip (the prototype of a reflector) was developed by crupin in 1779. The first spot light in the world was the light in the krupin reflector, which at the time was called an incomparably strong light. Such mirrors were used to concentrate the flux of the two light sources mounted in front of the vehicle's light source, reflecting back into a narrow solid Angle and forming a high-intensity beam of light. In addition to the headlights, the car had to be equipped with a red window facing back, the prototype of a signal light. Later, there appeared the license light with acetylene as the light source. Because it was unreliable and dangerous to supply acetylene to the license light with rubber hose, we had to use kerosene lamp as the rear light of the car.
In 1879, when the incandescent electric light bulb appeared, it was natural to think of applying it to cars, but the initial attempt failed. Because the vacuum the filament of an incandescent light bulb is made of carbon filament, very fragile, cannot afford cars shock vibration, is the outline of its brightness is not high, only about 4 * 10000 CD/m (CD - candela, light intensity unit), and at the beginning of the car in front of the 100 m to produce 1 lx (1 l - lux, illumination unit) the intensity of illumination, at least need light outline brightness is 32 * 10000 CD/m. By 1905, acetylene was used as a light source for car lights. This is because the profile brightness of a flame such as acetylene is about 7.2*10000cd/m, almost twice as bright as that of a light bulb at the time. Acetylene is produced by the chemical reaction of calcium carbide and water by means of a portable acetylene generator mounted on a car pedal or frame. The bumps and jolts of the car during driving are just the catalyst for this chemical reaction. At that time, there have been other highly light source, while also tried in the car, but were unsuccessful because of a variety of reasons, finally only acetylene lamp be early light stability of light source, and has been used to around 1925.
3. In 1913, an inflatable (inert gas) incandescent light bulb with tungsten filament was invented, increasing the luminous efficiency from 1lm/W of carbon filament incandescent light bulb to 15lm -- 18lm/W. The United States began the era of automotive electrical lighting by using it on Cadillac's headlights. Cadillac's headlamps began to use reflective tiles (the earliest reflectors) to increase the use of light energy and increase lighting. However, acetylene headlamps continued to be used for a long time, only gradually replaced by electric light source headlamps. This was caused by the use of a high voltage magnetic motor, which was itself an independent power source, and the use of a hand crank to start a generator. The car has neither a generator nor a battery.
Invented in 1912 to start the electric starter generators, this request in the must device, battery for battery charging device requires a tributary of the generator, it's for the car USES electric lighting provides the necessary conditions, is also the inevitable trend of development. However, automobile electrical equipment (starter, generator, battery, and electric lighting equipment) in every car is not have at that time, but according to user requirements and installation options. All cars are made with electric lighting, actually starting in 1925, and since then electrical equipment systems have become a necessity for every car. Car lamps are the only electric light source in blue.
4. Symmetrical light lighting headlamps headlamps early consists of light bulbs, mirrors and protective glass (later, with the advent of enclosed headlamps, to distinguish, this form is called semi-closed). Give out the central symmetrical beam, like a flashlight, only lighting function, no anti-glare function. With the increase of speed, the brightness of the headlights is required to increase, which makes the dazzling problem of the oncoming drivers become prominent. There are serious problems in traffic accidents and crashes caused by drivers' blinding eyes caused by the bright light of headlights when they meet vehicles. It puts forward two conflicting demands for headlamp: on the one hand, make the car at least 100 m distance of the road and obstacles for at least two meters to 2.5 meters get enough illume, this requires the greatest luminous intensity headlamps to over 10000 CD; On the other hand, make sure the headlight does not dazzle the driver of the oncoming vehicle, which requires that the light intensity in front of the oncoming vehicle should not exceed 400cd. Such a wide range of contrast set in the headlamp, this problem has been the headlamp designers have been working hard to solve the main contradiction.
5. In order to solve the contradiction between road lighting and the dazzle of the oncoming driver, the double filament headlamp was invented in Europe in 1924. The headlamp USES two filaments of the same bulb as the headlamp (far light) and the headlamp (near light). The underside of the near-light filament is fitted with a hood that blocks the light from the driver who is throwing it at the oncoming vehicle. Only under 1.25m part of the vehicle is illuminated on the half side of the road in front of the vehicle, so as to prevent the driver of the vehicle in front of the vehicle from dazzling. In the front of the car, the road is illuminated with high brightness, which is far enough (over 100 meters) and high enough (over 2 meters) to ensure good lighting ahead of the car. Since 1932, another asymmetrical near-light headlight has been developed in the United States. Although without clear European lamp light and shade as line is special designed by mirrors and lens, make the low beam width of each light is restricted, so that the high brightness light to illuminate the road ahead, on the local only head on one side to the car only weak light illumination. Due to the requirement of asymmetric beam, the protective glass in front of the lamp becomes the light distribution mirror, and many optical patterns are produced on it, which can change the light field according to the need and redistribute the light.
Logistic's closed-end headlamps were developed in the United States after 1940. The far-light filament is designed to be short straight cylindrical and placed in the focal point of the reflector. And filament of the low beam position design in slightly higher than the optical axis of the horizontal plane, after making the beam through the mirror reflection to the optical axis tilted below and to the right offset (to the right), make the low beam light field asymmetry. In 1955, the above system was improved to increase the axis of the far-beam by 0.5 degrees, and a light distribution screen was adopted to ensure that the driver's eyes of the oncoming vehicle were not exposed to the direct exposure of the near-light filament.
After the halogen tungsten lamp was developed in the late 1950s, it was quickly adopted by the headlamp, which significantly improved the asymmetrical near-light headlamp system. The halogen tungsten lamp used in the headlamp is mainly single filament H3 and double filament H4. Its luminous efficiency can reach 221m/w ~ 251m /w, which is about 50% higher than the general incandescent bulb, and the life of the bulb is also greatly improved.
In the whole development of electric light source, paraboloid reflector is used in the headlamp. The reflector is a parabola that rotates around its axis, collecting and converging light from the bulb and shooting it out parallel to the axis. Lighting distribution in accordance with the regulations is achieved by the combined action of light bulbs, reflectors and lighting distribution. The mirrors have been in use for a long time, about half a century.
8. Free surface headlamps Free curved surface (FF) headlamp reflector surface is not the rules of geometry, it is the computer through the complexity of computation and optimization of critical parameters, application simulation of 3 d surface. Do not need lens the headlamps, from free surface mirror reflected light is light type to meet the requirements of laws and regulations, that is, it played a dual role parabolic reflector and the lens in the headlamps. Reflectors are also not made from metal materials, but from a precision injection molding process using Bulk M oulding Compound (BMC). There is no need to design an optical pattern for the lens. It is a non-striated lens and its material is no longer glass, but polycarbonate (PC) plastic. Free-form surface headlamps are a major advance in design, construction or materials.
9. The former electric light source of projection headlamp is called reflector headlamp because of its structural characteristics. In 1984, the federal hela headlamp company of Germany introduced a new generation of headlamps -- projection headlamps (also known as DE lamps), which were put into mass production since 1990. Projection headlight consists of light bulb, reflector, baffle, convex lens and distribution lens. It requires accurate assembly to obtain accurate and clear bright and dark cut-off lines. In recent years, projection headlights have also been used in luxury cars produced in China.
High intensity discharge lamp stands for HID lamp, also called gas discharge lamp. European regulations have approved the use of the lamp since 1995. BMW, Mercedes, porsche, audi and other luxury cars now use these headlamps one after another. D2R bulbs are suitable for reflective headlamps. D2S light bulb is suitable for projection headlight. The bulb's starting voltage is 25KV, and the power is still supplied by the 12V dc. The HID lamp can be used as a stripless plastic lens, a reflector and a projection lens. Of course, you can also use a free-form surface reflector. This kind of luminaire has many advantages, such as high luminous efficiency, high brightness, low energy consumption, high reliability, long life and not being affected by the fluctuation of vehicle voltage.
Fiber optic headlamp fiber optic headlamp is the latest generation of automobile lamps developed according to the principle of full reflection of light. It consists of light source, reflector, optical fiber and output components. Optical fiber headlamps can be used as both headlamps and fog lamps, and more widely used in various kinds of indoor lighting. Fiber optic lighting technology has changed the structure of traditional automobile lamps and lanterns and will bring the technology of automobile lamps into a new era. But it is still in development, and its high cost limits its use in car products. Once the obstacles are overcome, fiber optic lighting technology will be rapidly and widely used in automobile production, which will make automobile lamps appear a new look.
Headlamps are the most demanding, complex, difficult to design and manufacture in the headlamps. Its development and change also represent the overall evolution of the headlights. As for the light, the light source is with the synchronous development of headlamp, its change also performance in terms of structure, such as combination lights, composite lights, and the latest popular mixed light will light left and right two parts together after combination after the integration of the whole lamp to wait. The use of light-emitting diode (LED) as the light source of the signal lamp is an innovation of the signal lamp. Neon lamp (neon lamp) is a new development of signal lamp in recent years.
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