Vehicle lighting has a lot of types of light bulbs, and each has its own functions and purpose. Lamps illuminate the interior, highlight the glove box, trunk, engine, dimensions warn about the upcoming car maneuvers, some use as signal lamps, but there are the most important - for lighting the road - headlights. The headlight is a part of the car, without which driving in the dark is almost impossible. The safety of the driver, the integrity of the car, and the preservation of the health or life of a pedestrian depend on this device. Needless to say, the quality of the roadway leaves much to be desired: huge holes are closer to the edge or a lot of small holes in the middle of the road - both of which in any case kill the chassis, wheels, shock absorbers. Therefore, you should carefully choose which type of lamps to put in the headlights: halogen, xenon or LED, and which is better suited to the specific conditions of operation of the vehicle.
Comparison of different types of headlights.
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Any vehicle is equipped with headlights. Depending on the size of the number of headlights may be different:
- one (for motorcycles);
- two (for cars, small cars);
- three or more (for huge trucks, construction equipment, special purpose vehicles).
The design of the headlamp is basically the same for any type of transport, but not as simple as you might think. Automobile headlights are located on the edges of the horizontal axis of the car. The headlight consists of four parts: emitter, reflector, diffuser, body. A light emitter is a lamp that stands in the spotlight, it is the only source of light, and without it the headlight does not work. Depending on the base material from which it is made, there are several types of such lamps:
- incandescent lamp;
Next comes the reflector. It reflects the light that the lamp emits. The reflector comes in different shapes and has many variations. It all depends on the design of the car, the style in which the front part is made, the location of the headlamp, but more often the cone-shaped reflector. It is made of glass, plastic, other polymeric material, on which there is a thin layer of aluminum deposition. Light, falling on such a deposition, is reflected by a multitude of rays, increasing its brightness. Reflectors can be both the simplest and with complex specific adjustments. Simple cones (parabolic) only reflect the rays in different directions, they can not be adjusted for brightness, intensity, direction.
Slightly more complex reflectors (free-form) are also static in this regard, but thanks to the division into several zones and a stepped design, the light is reflected by individual beams, and therefore becomes more distinct, when scattered, it does not lose so much light flux, less blinding by-passing machines. There are also lens headlights. Their reflectors have a specific elliptical shape and are additionally equipped with a shutter that cuts off the flow of light. That is, the light in the design of the headlamp is reflected several times before getting on the lens, and then on the road.
The role of the scatterer is also great. Usually it is made of glass or polymer, in appearance and characteristics similar to it. Protects the headlamp from possible external damage, diffuses the light and directs it to the desired point. On the lens there are serifs or recesses, through which you can get the desired angle of illumination. Such diffusers are now used less frequently. More popular are simple diffusers without optical additions made from ordinary plastic. They do not direct the light, but simply perform the basic function of protection against pollution, water, and mechanical external damage.
The principle of the halogen backlight
The halogen light source works on the incandescent principle. Inside it are a tungsten filament that is heated by electricity, as well as pairs of halogen elements (most often it is bromine or iodine). Under the influence of these vapors, the atoms of tungsten do not settle as quickly as in an incandescent lamp, they begin to move around the filament and often stick to it. The light from such a lamp has a yellowish tint. It works well on AC and DC.
Xenon light sources
Xenon light sources are different from halogen-colored colors, and also have differences in terms of operation. There is a big difference in the principle of operation - in the xenon lamp tungsten also acts as a catalyst, but thorium is added to it, and the whole space is filled with xenon. Under the action of electricity, a plasma arc arises near the cathode in a xenon lamp. This lamp exudes a bright white light that is as close to daylight as possible - 3000 lumens.
There are short-arc, long-arc (tubular), ceramic xenon. Accordingly, the lamps with a short arc, where the electrodes are close to each other, and the bulb is similar to a ball, the lamps with a long arc, where the electrodes are at a distance in the flask, which is more like a tube, the ceramic lamps are also with a short arc, but in a ceramic shell and therefore safe to install and do not require adjustment. For the first time such lamps began to be used in the German automotive industry.
LED car lights
LEDs have become very popular lately. It is a semiconductor that produces optical radiation when electricity passes through it. The crystal of the LED emits a specific color of the light flux. The principle of operation of such a lamp involves passing a current through a special transition, where charge carriers disappear and then are replaced by photon radiation. That is, the electrons move from one level to another. The LED is connected directly to the current source, and connected to the voltage source through a resistor. It is worth noting that they do not heat up, but simply exude light. The device and the principle of operation are being actively improved lately, as the technology of quantum dots and photonic crystals.
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All types of lamps for headlights are in demand. The main indicators for comparison are service life, luminous flux, maintenance, cost, operating conditions. Some motorists arrange the whole test drives for different types of headlights under different conditions. Information about such tests can be easily found on the net. Moreover, such tests usually have a very wide range in terms of different lighting conditions, season, road quality. It also takes into account how light the borders of light shake when traveling through irregularities, how fast the switching from distant to dim light occurs, what maximum distance the light emission reaches.
Advantages and disadvantages of halogen lamps
It is difficult to say which lamps better illuminate the road, and generally perform the function assigned to them. The lamp itself can be quite good in all respects, but the headlamp device levels its merits if it is chosen incorrectly. Galogenki - the most common light sources for headlights, because they began to use before the others. In fact, they are advanced incandescent bulbs.
The use of such lamps for cars has several advantages:
- They are inexpensive. Of all the possible options, halogen lamps will be the cheapest option.
- They are easy to replace. The lamp device does not carry any special danger, does not require special conditions for replacement.
- They can be very compact. If the volume of the flask is small, it increases the pressure, thereby reducing the rate of evaporation of the thread.
- Lamps normally respond to alternating current. Can work at an alternating or direct current, without losing the efficiency.
The disadvantages of halogen lamps include a short lifetime - up to 1000 hours, in which both diodes and xenon headlights benefit from them. This is due to the fact that the return of tungsten atoms to the spiral occurs unevenly and often depends on the heating temperature, so the spiral is inevitably destroyed. It is not very good that the optics heats up very much, it does not transmit enough bright light, and therefore does not illuminate the road so effectively.
Pros and cons of LED models
Lexus manufacturers began to use the LED manufacturers in 2007 in the head lighting. In the high beam, such lamps can illuminate a few hundred meters. But at the same time the light does not blind oncoming drivers. Car owners note the concentration of light on the road without dispersing or any spots.
LED headlights have many advantages over other lamps:
- They are very durable. Able to work from 10,000 to 100,000 hours. If a day such lamps will work 8 hours, then they will be enough for 34 years. It is worth noting that with such a long work the crystal will lose its brightness.
- The diode consumes a minimum of energy. The load on the generator will be pleasantly low, because the crystal is a semiconductor.
- Durability and reliability. There are no sensitive parts such as tungsten filament in the lamp structure. Therefore, the LED is very well tolerate low temperatures.
- The crystals provide a glow of white color, which can not be compared with halogens or xenon. The color is not achieved using filters or refraction, but through the source itself. The spectrum of white - from 2700 K to 6500 K.
It is worth noting that the most important disadvantage of LEDs is called high price. It is impossible to find offers on the market that are equal in value with xenon. The problem is also in the fact that the design sometimes does not provide for a sufficient number of lamps to achieve a good luminous flux. And because the efficiency of the light flux will not always be better than analogues.
Advantages and disadvantages of xenon
Lamps filled with xenon are gas-discharge. The first time it was used in the concern BMW. The system of such headlights usually includes an ignition unit and an electronic control unit. They provide the appearance of a discharge due to an alternating current of 10 - 20 kV. Often, these headlights go as bi-xenon, because it is not advisable to put xenon on dipped and main beam separately.
The dilemma of xenon or halogen can be sorted out by considering their advantages. The advantages of halogen are already described, so let's move on to xenon:
- The service life is much longer than halogen. It reaches the mark of 3000 hours.
- Luminous flux is much brighter than halogen. Unlike the proposed 1000 - 1500 lumens, xenon has 2500 - 4000 lumens. Well illuminated not only the road, but the curb.
- Lamps consume less electrical energy. They need a large discharge for the impulse to turn on, and then the lamp operates on alternating current than it does not load the generator at all.
- Low optics It may be noted that it is better - xenon or LED lamps - will indicate this parameter. Galogenki compared with them very hot.
There are, of course, disadvantages. Lamps of reduced power are quite expensive. Xenon need to be replaced in two headlights at once. Many are afraid to use such lamps because of the use of mercury in them, considering them dangerous because of this. But its specific gravity is not so high as to harm the health of the driver. Because of the scatterer's pollution, the headlight sometimes shines, interfering with the opposite flow, or scatters light in different directions. But the brightness of LED or xenon can have equal performance. The brightness of LEDs depends on their number in the headlamp. For example, Seat is equipped with diodes for 1600 - 1700 lumens, which is even less than the standard xenon lamp indicators.
What lamps do you choose for a car?
To choose a car lamp, you need to take into account all the advantages and disadvantages of products offered on the market. There are inexpensive lamps with good performance and fairly effective performance. Modern machines are equipped with such lighting, which eliminates the use of a certain type of lamp.
For example, the halogen headlamp device in the Dacia Duster has the same performance indicators as xenon headlamps. LEDs also have a pleasant shade and a very long service life. Xenon headlights on light traffic are brighter than LED lamps. Therefore, before choosing a lamp in your car, pay attention to the device of the headlight itself.