How the LED works: how it works

Translated from English, the abbreviation LED means literally "a diode that emits light." It is a semiconductor device capable of transforming electric current into light radiation. This is a simple device, the design of which is quite different from the usual products for lighting (incandescent lamps, discharge lamps, fluorescent lamps, etc.).

How the LED works will be interesting for everyone. This device does not have initially unreliable fragile structural elements and a glass bulb (unlike other lamps). The cost of diodes is so small that it is not much different from the batteries that serve as their source of power. The popularity of such products is explained by a number of factors, including their design.

History of occurrence

Considering the question of why LEDs work, one should study the history of their occurrence. For the first time such a device was created in 1962 by the scientist N. Holonyak. It was a monochrome red light diode. It had a number of shortcomings, but the technology itself was recognized as promising.

Ten years after the creation of the red diode appeared green and yellow varieties. They were used as indicators in many electronic devices. The intensity of the light flux of diodes due to scientific developments has constantly increased. In the 90s, an illuminator with a flow efficiency of 1 lumen was created.

In 1993, S. Nakamura created the first blue diode, which was characterized by high brightness. From this moment it became possible to create any color spectrum (including white). Technology has been developing relentlessly.

When a blue and ultraviolet type of diodes are combined, a white phosphor illuminator is obtained. They gradually began to displace incandescent lamps. By 2005, diodes were produced with a luminous flux of up to 100 lm and even higher. Steel began to produce white lighting with different shades (warm, cold).

LED device

To understand how a point light-emitting diode works, it is necessary to consider its device in detail. This lighting device, in the opinion of the representatives of the Association for the Development of the Optoelectronic Industry and the Energy Department, will soon become the most popular source of lighting in ordinary houses, offices, institutions.

The LED is based on a semiconductor crystal. It transmits electric current only in one direction. The crystal is located on a special substrate. It does not conduct current. The body protects the crystal from external influences. It has outputs in the form of contacts, as well as an optical system.

To increase the operating time of the device, the space between the plastic lens and the crystal itself was filled with a transparent silicone component. To remove excess heat, an aluminum base is used. This is the usual device of a modern diode. When working, it releases a relatively small amount of heat. This is also an advantage of the device.

Principle of operation

Considering how the LED works, it is necessary to understand the basic principle of operation of such devices. The device of the presented type has one electron-hole transition. This is due to the different principle of conductivity of the components of the illuminator. One semiconductor has an excess of electrons, and the other has excess holes.

With the aid of the doping process, the perforated material is enriched with negative charge carriers. If a current is applied at the place where semiconductors are enriched with opposite charges, a direct displacement is obtained. Through the transition of these two materials, electricity will run.

In this case, in the diode body there is a fusion of charge carriers with different electrical status. When holes and electrons collide, a certain amount of energy is released. This is the quantum of the light flux. It is called a photon.

LED Color

When creating diodes, various semiconductor materials are used. This determines the color that is emitted during operation of the presented device. Different materials are capable of sending waves of different lengths into space. This allows the human eye to see this or that color of the visible spectrum.

Studying the question of how the LED works, one should consider the materials of semiconductors. Previously, gallium phosphide, triple GaAsP, AlGaAs compounds were used for such purposes. At the same time, the device could send a red, yellow-green light stream into the space .

The presented technology is now used only for indicator devices. Today for such products use aluminum indium-gallium (AllnGaP) and indium-nitride gallium (InGaN). They withstand a fairly high level of passing current, high humidity and heating. A combination of different types of LEDs is possible.

Blending colors

Modern diode tapes can produce different shades of light. One device can produce a monotonous color. When creating a multi-crystal device it is possible to get a huge number of different shades. Like a TV or computer monitor, the diode can create any color using the RGB model (stands for red, green, blue).

This is a simple principle that allows you to understand how RGB LEDs work. With this technology, you can create and white lighting. To do this, all three colors are mixed in equal proportions.

However, in addition to the technology presented, it is possible to obtain a white glow when a short-wave radiation diode (ultraviolet, blue) is connected together with a yellow phosphor type coating. With a combination of photons of yellow and blue, the result is a white glow.

Production

To understand how many volts the light-emitting diodes work on, it is necessary to consider the production of these devices. First of all, it should be noted that devices with a matrix type RGB are more expensive than luminescents. And the latter allow to achieve high quality lighting.

The disadvantage of phosphors is a lower light output, as well as a different color (temperature) of the flow. This device ages faster than the LED. Therefore, lighting devices of both principles of operation are on sale. To create indicators, diodes with a consumption of 2-4 V of constant voltage (at a current of 50 mA) are produced.

To create high-grade lighting, devices with the same voltage consumption are required, but a higher current level is up to 1 A. If one diodes are connected in series in one module, the total voltage will reach 12 or 24 V.

Amplification of brightness

Considering the question of what voltage the light-emitting diodes are working on, it should be said about increasing the brightness of the presented devices. The power of such devices reaches 60 mW. If such diodes are installed in a medium-sized body, light elements need to be set to 15-20 pcs.

Diodes with increased luminescence brightness can carry a power of up to 240 watts. To ensure normal backlighting, similar elements will require 4-8 pieces. On sale are devices that can fully illuminate the premises, outdoor advertising, display cases, etc. Some tapes are created for medium or low intensity lighting.

To connect the presented equipment, control units of appropriate power are used. For color tapes, it is possible to use controllers that control not only the intensity of the lighting, but also the tones and modes of operation of the device.

Glow control

There is a huge number of options for the equipment presented. There are LEDs working on batteries (for example, in flashlights), fed into a stationary network. They are used for both internal and external work. Depending on the application conditions, the appropriate diode protection class is selected.

To adjust the brightness of the glow, the supply voltage is not reduced. Pulse width modulation (PWM) is used to reduce the luminescence intensity. In this case, the control unit is purchased.

The presented method consists in supplying a diode with a pulse-modulated current. The signal frequency reaches thousands of hertz. The width of pulses and intervals of pauses can vary. You can control the glow of the device. The diode in this case will not go out.

Durability

Diodes are considered durable devices. This is due to their design. However, if the LEDs on the lamp do not work, it is possible that their operation has expired. This can be determined by the saturation of the glow and the color change.

Also, experts note that the life of low-power devices is much longer. But even in the brightest ribbons or lamps, diodes are guaranteed to work 20-50 thousand hours. Since they do not have brittle structural elements, mechanical influences are more likely to not harm such lighters.

Having studied how the LED works, one can understand the principle of the device's design, as well as its performance characteristics. This equipment is considered to be the illuminator of the future generation.