Lighting Systems in Cars

The system of lighting a car (and in general of any vehicle that exposed a public thoroughfare) is essential because, as you know, it allows us to see and be seen. Although not we realize, it is one system of security (and not just a set of lights that allow us to drive at night). Since the car is car has evolved at the same time that the available technology.

Being already guaranteed the “ be seen ” (just don’t be in the dark), this section has evolved little. The addition of daytime running lamps could be considered the latest iteration (whether they are mandatory on cars that are manufactured in Europe), as well as the introduction of lamps of lower consumption (LEDs, for example, which itself already aren’t even lamps as such). Where if has been a breakthrough in the last 10 or 15 years is in the section of “ see ” more and better.

Types of lamps or LEDs

Four types are (colloquially bulbs) lamps that are today mounted on our cars and are not exactly modern. Incandescent (or incandescent) lamps have more than 130 years old (although some have evolved at this time), while the so fashionable LEDs has (perhaps not believe it you) more than 80 years already.


In lamps incandescent, passing electric current by a metal filament (tungsten today), which acts as resistance, this is red and clear light (and heat). Filament is enclosed in a blister of glass inside of which the vacuum has been made (either it is filled with a noble gas, krypton for example). They are the most inefficient (i.e. those most consuming) and the less lasting, so it may have its days numbered.


Lamps Halogen: the principle is the same, only that if the blister with a halogen gas is filled instead of vacuum, filament lasts longer and gives off more light (with the same consumption) and whiter.

As higher temperatures are reached, the blister is not glass sand silica (conventional glass), but glass from quartz sand (and for that reason, when placed, blister of a halogen bulb, do not touch with bare fingers since the pH slightly acid (FAT and skin of the sweat which can detach) damages that type of glass.

They were the first big change in the headlights of cars allowing more light (and not long ago about 30 – 35 years approximately).


Lamps of Xenon (or HID, for High Intensity Discharge): also known as gas-discharge lamps. We don’t have a filament, but two electrodes tungsten very near, but not in contact within a blister of quartz glass. The ampoule is filled with vapor of mercury, metal salts and xenon gas. To get current to one of the electrodes, “ jump ” up to the other causing an electric arc that gives off lots of very white light (slightly bluish).

Oddly enough (as it is needed a high voltage to the ignition impulse), during operation consume less than halogen lamps (in front 55 W 35 W only crossing in the halogen light).

This type of lamp has been another big change in automotive lighting, as it still has more light, more homogeneous and more white (eye gets tired less). Although at the expense of a much higher price. A halogen lamp can cost about 12 to 18 euros per unit, whereas a xenon lamp can cost about 150 to 200 euros per unit. It is assumed that they last longer. In principle they are used in the light of crossing (short), but also in the light of (long) road.


The light-emitting diodes (LED), very basically, consists in a semiconductor material encapsulated in a tiny plastic lens. Doing through power LED to low voltage, it emits light (I will not talk of electrons or photons for simplicity).

They are the big bet of recent years. Whether for aesthetic, or by its lower consumption (very useful for example in electric cars), increasingly are more cars with headlights or pilots of leds. In the daytime running lights are being imposed without a doubt (because you have a very high-sheen), but also see them more and more in the rear position lights, brake lights or direction (turn signal) indicator lamps.

In high-performance headlamps LEDs are being used in the low-beam light. The drawback of led lights is that they are considerably more expensive (but also have a lifespan much greater). However, concerning the price of a car, nor is a rising so high.

An example of a compact, reasonably affordable, and also hybrid car carrying daytime position lights of LEDs in series is the Toyota Auris HSD (of which I have spoken in detail in Motorpasión future). Between electric cars that are sold in Spain, the Nissan LEAF has LEDs in their subsequent pilots, as well as in the front position lamp.

Lighthouse design, projectors and reflectors

Years ago the headlights were translucent. The dispersion glass it it not allowed to see inside. In fact the Crystal was the protagonist because he was carving (or molded economy) internally from a point of view optical (forming horizontal prisms), and was in charge of distributing the light beam.

We have today changed to transparent crystals of dispersion (usually polycarbonate, and eye, sensitive to UV radiation, so deteriorate if they get too much sun). So to control the distribution of the beam of light generated by the lamp, it is hoped the geometric design of the reflector, either elliptical or parabolic, or ellipsoidal lens (in projection headlights, which get about 10% more light).

More visibility: fog lights and headlight washer

For many years drivers have wanted more light, and in different circumstances, thus was born the headlights and complementary strategies.

  • The headlights fog they are characterized by generating a beam of light, short and wide, which is directed towards the ground, trying to minimize the scattering of light that occurs through clouds of dust, sand or smoke and fog. It is very difficult to pass through the fog (tiny water droplets suspended in the air).
  • The headlight washer they were another strategy to have more light when things got complicated. Since then they have not had much success. Formerly consisted of a water dispenser and a limpiafaro of rubber, today have been simplified (and cheaper) with pressurized water jets (which can be fixed or retractable).

Additional light-turns

Additional lights in turns is something quite recent, in fact even if they do not have a high cost, are not many cars which bring it as standard equipment (although increasingly). Consists of an additional light in the light of the cross, on the side toward which is by turning the handwheel, illuminating not forward, but to the side.

It is very simple, only there is a turn in the direction, triggering the light from a certain angle of rotation of the steering wheel sensor. There is one bulb, either in the main lighthouse, or the fog light (sometimes simpler systems do not add any more lights, and use only the own of the fog light, although it is not ideal).

This light usually operate only at low speeds (up to 40 or 50 km/h approximately, in some cases even up to 70 km/h) and eliminates areas in darkness in the turns closed (for example at intersections), with an angle of 65 degrees and up to about 30 m range.

Self-igniting lights

As the human being tends to be lazy (or clueless) the ever-increasing amount of electronics in our cars allows to integrate a small light sensor on the windshield (usually at the top, behind the mirror). Typically, this sensor is a photodiode (again a diode and a semiconductor material) that he is excited by light and generates certain electrical current.

When there is less light (it has set a limit) the current decreases or ceases, then is when a small microprocessor turns the dipped-beam headlamps and (when it returns to have light, off them).


We have already seen that there are additional lights for rotations, but serve little when we are on road to middle or high speed (more than anything because they are low power and range lights). So I had to think something to better illuminate the curves, Since the beam is projected in a straight line towards the outside of the curve, leaving little illuminated the inside of it.

The idea was to turn the lighthouse (or at least one part of it). Typically, make that rotated by a small unit of the dipped-beam, normally of projector type with an ellipsoidal lens (behind which is the lamp), electric motor rotating a number of degrees according to what is turning the steering wheel.

The result is that the headlamp beam is oriented towards curve and tour with the car. Typically, the headlights to rotate between 10 and 15 degrees, which earn about 20 to 30 metres of walkway lighting.

Automatic Adaptive Headlights

The simplest system began with the height adjustment crossing in xenon headlights light. As this type of headlights can dazzle more drivers with which we cross, won an automatic system that instantly correct height to always keep the optimum height.

Through sensors in the suspension (at the rear axle and the front axle), the microprocessor can tell what angle of nod has car. When accelerating (and carrying too much weight in the trunk) is positive (the beam of light “ gets ”) and braking angle is negative (the beam of light “ is lowered ”).

So again a few small electric motors corrected slightly down or slightly up the lighthouse, to maintain the height of the beam of light.

Another system that is being introduced is the of high beam (largas) Automatic. Knowing the speed at which circulates the car (usually is set at speeds above 70 km/h), again a light sensor lets you know the microprocessor if comes a vehicle in the opposite direction or if we just advance (detected in their headlights) and choose to automatically remove long lights to not dazzle you. When you have darkness returns to the main-beam headlamps.

The latest and most sophisticated is the adaptation of the light in an active way (or Adaptive headlamps), at various levels, either on an ongoing basis, combining all systems that I’ve explained previously. In this case the electronic lighting control unit is permanently processing data speed, brightness, rotation of the steering wheel angle and angle of yaw (of effective rotation of the vehicle).

These data are adapted automatically the lights for the best possible lighting. If it is on several levels, it is normal have dipped-beam (complemented by the cornering light) and two or three levels in beam, one for roads (up to 90 km/h), in which the beam is wider, especially towards the left, and two more for motorway, from 90 km/h (increasing the power of xenon lamps to have more light intensity and starting from) 110 km/h rising somewhat the lighthouse to have more scope.

If the system is still more advanced, then change is not by levels, but on an ongoing basis, adapting to the distance What with vehicles that precede us (as measured by a radar), or with vehicles that we came across, again by varying the power of lamps or by varying the height of the lighthouse, so that the headlamp cone ends always in front of other vehicles, without any risk of glare.

For lights long in addition to vary the height of the lighthouse with servomotors (small electric motors), you can also choose to use variable shutters (that is operated electrically, depending on what they consider the microprocessor), to partially plug (the part above) lamp, so the beam para que el haz sea is low, and they can go by uncovering it, either hit (two positions, short/long), either progressive (continuous variation), so that the beam is also high (and thus have road light that can illuminate up to 300 m in front of the car).

Even the almost total adaptability of the lighthouse can be used to improve the conditions of visibility in case of fog, and complement the specific fog lights. The Lighthouse is oriented down (to the ground) and outward, to reduce glare and increase the width of the field of vision.

Night vision systems

Although they are not a proper lighting system, that allow “ more ” during the night, so I decided to talk about them in this article. The image “ night ” obtained can be projected on the windshield, using a system HUD, either display on LCD displays or OLED color screen in the center console, or even a navigation system screen within dashboard.

They are used for night vision infrared cameras not refrigerated (active thermal cameras can be called also). The main headlights incorporate an infrared filter so that they light the road with ultraviolet light. A monocular infrared camera placed at the top of the windshield (or sometimes in the bumper or Grill) does see it illuminated by the light (reflected by the pedestrian, animal or object) and that the eye would not be able to see. There is already a system that does not require the previous emission.

Night vision can be improved with systems of recognition of pedestrians (that visually alert the driver) and performed automatically flashes, either with a specific light illuminating the pedestrian (for example BMW Dymanic Light Spot). The scope of these systems is about 80 m.

The most advanced systems of which I have spoken unto tend to be available only as an option on cars of high range (usually brand premium, such as Mercedes-Benz and BMW, among others). Some generalist brands like Opel, given as an option on cars like the Astra (for 800 euros), an advanced lighting system (called AFL) Although not as sophisticated as the high-end brands.

However, as it has happened with other technologies in the automobile, it is very likely that over the years (10, 15, 20, we will see), are spreading in more affordable models and brands. Everything for the safety.