In incandescent lamps, light comes from a white-hot tungsten filament, essentially from heat. Like hot coals in a furnace heated by the thermal action of an electric current, when electrons oscillate rapidly and collide with the nodes of the crystal lattice of a conducting metal, while emitting visible light, which, however, accounts for only less than 15% of the total expended electrical energy that powers the lamp .

LEDs, unlike incandescent lamps, emit light not at all due to heat, but due to the peculiarity of their design, which is fundamentally aimed at ensuring that the current energy is used specifically for the emission of light, and of a certain wavelength. As a result, the efficiency of the LED as a light source exceeds 50%.

The current passes here, and at the transition there is a recombination of electrons and holes with the emission of photons (quanta) of visible light with a certain frequency, and therefore with a certain color.

Any LED is fundamentally designed as follows. Firstly, as noted above, there is an electron-hole junction here, consisting of p-type semiconductors (the main current carriers are holes) and n-type (the main current carriers are electrons) in contact with each other.

When a current is passed in the forward direction through this junction, then at the point of contact of semiconductors of two opposite types, a charge transition occurs (charge carriers jump between energy levels) from a region with one type of conductivity to a region with another type of conductivity.

In this case, electrons with their negative charge combine with ions of positively charged holes. At this moment, photons of light are born, the frequency of which is proportional to the difference in the energy levels of atoms (the height of the potential barrier) between substances on both sides of the transition.

Structurally, LEDs come in various forms. The simplest form is a five-millimeter body - a lens. Such LEDs can often be found as indicator lights on various household appliances.The top of the LED housing has the shape of a lens. A parabolic reflector (reflector) is installed at the bottom inside the housing.

The reflector contains a crystal that emits light where current passes through the p-n junction. From the cathode - to the anode, from the reflector - towards the thin wire, electrons move through the cube - the crystal.

This semiconductor crystal is the main element of the LED. Here it measures 0.3 by 0.3 by 0.25 mm. The crystal is connected to the anode by a jumper made of thin wire. The polymer body is also a transparent lens that focuses light in a certain direction, resulting in a limited divergence angle of the light beam.

Today, LEDs are available in all colors of the rainbow, from ultraviolet and white to red and infrared. The most common are red, orange, yellow, green, blue and white LED colors. And the color of the glow here is not determined by the color of the body!

The color depends on the wavelength of the photons emitted at the pn junction. For example, the red color of a red LED has a characteristic wavelength from 610 to 760 nm. The wavelength, in turn, depends on the material that was used in the production of a particular LED. Thus, to obtain colors from red to yellow, admixtures of aluminum, indium, gallium and phosphorus are used.

To obtain colors from green to blue - nitrogen, gallium, indium. To obtain white color, a special phosphor is added to the crystal, which converts blue color to white using.

LEDs were invented about half a century ago as a more convenient alternative to miniature incandescent lamps. The new lighting elements were more convenient, easier to use and energy efficient. Over the past 30 years, LEDs have been improved and refined, capturing an increasingly large part of the market. The reason for its great popularity was the operational reliability, long working life and simple principle of operation of the LED.

Historical reference

Historically, the inventors of LEDs are considered to be physicists G. Round, O. Losev and N. Holonyak, who in their own way complemented the technology in 1907, 1927 and 1962, respectively:

1. G. Round studied the emission of light by a solid-state diode and discovered electroluminescence.
2. O. V. Losev, in the course of experiments, discovered the electroluminescence of a semiconductor junction and patented a “light relay”.
3. N. Holonyak is considered the inventor of the first LED used in practice.

Holonyak's LED glowed in the red range. His followers and developers in subsequent years developed yellow, blue and green LEDs. The first high-brightness element for use in fiber optic lines was developed in 1976. The blue LED was designed in the early 1990s by a trio of Japanese researchers: Nakamura, Amano and Akasaki.

This development was characterized by extremely low cost and, in fact, ushered in the era of widespread use of LEDs. In 2014, Japanese engineers received the Nobel Prize in Physics for this.

In today's world, LEDs are found everywhere:

• in external and internal lighting with LED lamps and strips;
• as indicators for alphanumeric displays;
• in advertising technology: tickers, street screens, stands, etc.;
• in traffic lights and street lighting;
• in road signs with LED equipment;
• in USB devices and toys;
• in the backlighting of TV displays and mobile devices.

LED device

The design of the LED is represented by the following components:

• epoxy lens;
• semiconductor crystal;
• reflector;
• wire contacts;
• electrodes (cathode and anode);
• flat cut base.

The working contacts are fixed to the base and pass through it. The other components of the lamp are located inside it in a sealed space. It is formed by the adhesion of the lens and the base. During assembly, a crystal is fixed on the cathode, and conductors are attached to the contacts, which are connected to the crystal through a p-n junction.

What is OLED?

OLEDs are organic semiconductor light-emitting diodes, which are made from organic components that glow when an electric current passes through them. For their production, multilayer thin-film structures made of various polymers are used. The operating principle of such LEDs is also based on a p-n junction. The advantages of OLED are manifested in the field of displays - compared to liquid crystal and plasma analogues, they benefit in brightness, contrast, power consumption and viewing angles. OLED technology is not used for the production of lighting and indicator LEDs.

How does the element work?

The operating principle of the LED is based on the functions and properties of the pn junction. It is understood as a special region in which a spatial change in the type of conductivity takes place (from the electron n-region to the hole p-region). A p-semiconductor carries a positive charge, and an n-semiconductor carries a negative charge (electrons).

In the LED design, the positive and negative electrodes are the anode and cathode, respectively. The surface of the electrodes, which is located outside the bulb, has metal contact pads to which the leads are soldered. Thus, after applying a positive charge to the anode and a negative charge to the cathode, an electric current begins to flow at the p-n junction.

When the power is turned on directly, holes from the region of the p-semiconductor and electrons from the region of the n-semiconductor will be directed to move towards each other. As a result of this, recombination occurs at the boundary of the hole-electron transition, that is, exchange, and light energy is released in the form of photons.

To convert photons into visible light, the material is selected so that their wavelength remains within the visible range of the color spectrum.

Types of LEDs

Consistent improvement of the technology discovered in 1962 has led to the creation of various basic elements and LED models based on them. Today, classification is carried out according to the design power, type of connection and type of housing.

In the first case, lighting and indicator options are distinguished. The first ones are intended for use for lighting purposes. Their power level is approximately the same as that of tungsten and fluorescent lamps. Indicator LEDs do not emit strong emissions and are used in electronic equipment, instrument and navigation panels, etc.

Indicator LEDs are distinguished by the type of connection into triple AlGaAs, triple GaAsP and double GaP. The abbreviations respectively stand for aluminum-gallium-arsenic, gallium-arsenic-phosphorus and gallium-phosphorus. AlGaAs emit yellow and orange within the visible spectrum, GaAsP emit red and yellow-green, and GaP emit green and orange.

Based on the type of housing, widely used LED lamps are now divided into:

• DIP. This is the old form factor of a lens, a pair of contacts and a crystal. Such LEDs are used in light displays and toys for illumination;
• « Piranha" or Superflux. This is a modified DIP model, which has not two, but four contacts. Releases less thermal energy and, accordingly, heats up less. Now used in automotive lighting;
• SMD. The most popular technology in the modern LED lighting market. This is a universal chip, which was mounted directly on the board. Used in most light sources, lighting lines, strips, etc.;
• COB. This is the result of improving SMD technology. These LEDs have several chips mounted on one board on an aluminum or ceramic base.

Technical characteristics and their dependence on each other

The main functional and operational parameters of LED lamps are:

• luminous flux intensity (brightness);
• operating voltage;
• current strength;
• color characteristics;
• wavelength.

LED voltage and brightness are directly proportional values ​​- the higher one is, the higher the other. But this is not the supply voltage, but the magnitude of the voltage drop across the device. In addition, the color of the LED depends on the voltage. Thus, the brightness, wavelength, voltage and color of the LED are related to each other, and their relationship is presented in the following table.

The operating principle of the microelement is designed in such a way that for stable operation in accordance with the nominal characteristics, it is necessary to monitor not the supply voltage, but the current strength. LEDs operate from pulsating or direct current, by adjusting the intensity of which you can change the brightness of the radiation. Indicator LEDs operate at a current in the range of 10-20 mA, and lighting LEDs - from 20 mA and above. So, for example, COB elements with four chips require 80 mA.

Color characteristic

The glow color of an LED element depends on the wavelength, which is measured in nanometers. To change the color of the glow, active substances are added to the semiconductor material at the production stage:

• semiconductors are treated with aluminum indium gallium (AlInGaP) to produce a red color;
• shades of green and blue-blue spectrum are obtained using indium gallium nitride (InGaN);
• to obtain a white glow based on a blue LED, its crystal is coated with a phosphor, which converts the blue spectrum into red and yellow light;
• for violet glow, indium gallium nitride is used;
• for orange – gallium phosphide arsenide;
• for blue – zinc selenide, silicon carbide or indium gallium nitride.

Similar to the method for obtaining a white glow, you can use phosphors of different colors to obtain additional shades. Thus, the red phosphor allows the production of pink and purple LEDs, and the green phosphor allows the production of light green LEDs. In both cases, the phosphor is applied to the substrate in the form of a blue LED.

Advantages

The features of how an LED works have given it several important operational and functional advantages over other types of electrical energy-to-light converters:

• modern LEDs are not inferior in terms of light output to metal halide and sodium gas-discharge lamps;
• the design almost completely eliminates the failure of any components due to vibration and mechanical damage;
• LED lamps are low-inertia, that is, they instantly reach full brightness after switching on;
• the modern range allows you to choose models with a spectrum from 2700 to 6500 K;
• impressive working life - up to 100,000 hours;
• affordability of indicator LEDs;
• LED lighting, as a rule, does not require high voltage and maintains fire safety;
• temperatures below 0°C have almost no effect on the performance of devices;
• The structure of the LED does not involve the use of phosphorus, mercury, other hazardous substances or ultraviolet radiation.

An LED is a two-wire semiconductor light source. When a suitable current is applied to the terminals, the electrons are able to recombine with the electron holes inside the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light is determined by the energy band gap of the semiconductor.

What is LED

A light-emitting diode is an optoelectronic device capable of emitting light when electric current passes through it. Light emitting diode only passes electric current in one direction and produces incoherent monochromatic or polychromatic radiation from the conversion of electrical energy.

He has several derivatives:

• OLED.
• AMOLED.
• FOLED.

Due to their luminous efficiency, LEDs currently represent 75% of the interior and automotive lighting market. They are used in the construction of flat screen TVs, namely for backlighting LCD screens or as a source of electricity. Used as main lighting in OLED TVs.

The first LEDs commercially available produced infrared, red, green, and then yellow light. The output of the blue LED, associated with technical and installation advances, makes it possible to cover a wavelength range extending from ultraviolet (350 nm) to infrared (2 thousand nm), which meets many needs. Many devices are equipped with composite LEDs (three in one component: red, green and blue) to display many colors.

LED lamp

LED lamps are lighting products for household, industrial and street lighting, in which the light source is LEDs. Essentially it is a set of LEDs and power circuitry to convert mains power to low voltage direct current.

The LED lamp is a separate and independent device. Its body is most often individual in design and specially designed for various lighting sources. A large number of lamps and their small size make it possible to place them in different places, assemble panels, and use them to backlight displays and televisions.

General purpose lighting requires white light. The operating principle of an LED lamp is based on the emission of light in a very narrow range of wavelengths: that is, the color characteristic of the energy of the semiconductor material that is used to make LEDs. To emit white light from an LED lamp, you must mix the emissions from red, green and blue LEDs or use a phosphor to convert parts of the light into other colors.

One method is RGB (red, green, blue), which is the use of multiple LED arrays, each emitting a different wavelength, in close proximity to create an overall white color.

The history of the creation of the first lamps

The first emission of light from a semiconductor dates back to 1907 and was discovered by Henry Joseph Round. In 1927, Oleg Vladimirovich Losev filed the first patent for what would later be called a light-emitting diode.

In 1955, Rubin Braunstein discovered the infrared emission of gallium arsenide, a semiconductor that would later be used by Nick Holonyak Jr. and S. Bevacca to create the first red LED in 1962. For several years, researchers limited themselves to certain colors, such as red (1962), yellow, green and, later, blue (1972).

Contribution of Japanese scientists

In the 1990s, research by Shuji Nakamura and Takashi Mukai of Nichia into InGaN semiconductor technology led to the creation of high-brightness blue LEDs, then adapted to white LEDs by adding a yellow phosphor. This advancement has enabled major new applications such as lighting and backlighting of television and LCD screens. On October 7, 2014, Shuji Nakamura, Isamu Akasaki and Hiroshi Amano received the Nobel Prize in Physics for their work on blue LEDs.

How the device works

When the diode is forward biased, electrons move quickly through the junction. They constantly unite, removing each other. Soon after the electrons start moving from n-type to p-type silicon, the diode connects to the holes and then disappears. Therefore, it makes the complete atom more stable and provides a small burst of energy in the form of a photon of light.

The principle of light wave formation

To understand how an LED works, you need to learn about its materials and their properties. LED is a specialized form of PN junction that uses a compound connection. The compound must be the semiconductor material used for the connection. Commonly used materials, including silicon and germanium, are simple elements, and a compound made from these materials does not emit light. As for semiconductors such as gallium arsenide, gallium phosphide and indium phosphide - they are composite, and compounds from these materials emit light.

These compound semiconductors are classified according to the valence bands that their constituents occupy. Gallium arsenide has a valency of three, and arsenic has a valence of five. This is called a group III-V semiconductor. There are a number of other semiconductors that fit into this designated category. There are semiconductors that are formed from group III-V materials.

The light-emitting diode emits light when it is biased forward. When a voltage is applied to a connection to cause it to move forward, current flows as with any PN connection. Holes from the p-type region and electrons from the n-type region enter the junction and recombine like a normal diode to allow current to flow. When this happens, energy is released.

It is found that most of the light is obtained from the transition region closer to the P-type region. The design of the diodes is made in such a way that this area is located as close as possible to the surface of the device so that the minimum amount of light is absorbed by the structure.

To produce light that can be seen, the connection must be optimized and the materials must be correct. Pure gallium arsenide releases energy in the infrared part of the spectrum. To bring light emission, aluminum is added to a semiconductor into the visible red spectrum to produce gallium argicide arsenide (AlGaAs). Phosphorus can also be added to produce red light. For other colors, different materials are used. For example, gallium phosphide produces green light, while calcium aluminum phosphide is used to produce yellow and orange light. Most LEDs are based on gallium semiconductors.

Quantum theory

The flow of current in semiconductors is caused by both flows of free electrons in the opposite direction. Therefore, there will be recombination due to the flow of these charge carriers.

Recombination shows that electrons in the conduction band descend to the valence band. When they jump from one band to another, they emit electromagnetic energy in the form of photons, and the photon energy is equal to the forbidden energy gap.

Mathematical equation displayed:

H is known as Planck's constant, and the speed of electromagnetic radiation is equal to the speed of light. Frequency radiation is related to the speed of light as f = c/λ. λ is denoted as the wavelength of electromagnetic radiation, and the equation becomes:

From this equation, one can understand how an LED works, based on the fact that the wavelength of electromagnetic radiation is inversely proportional to the bandgap. In general, the total emission of an electromagnetic wave during recombination is in the form of infrared radiation. It is impossible to see the wavelength of infrared radiation because it is outside the visible range.

Infrared radiation is called heat because silicon and germanium semiconductors are not direct gap semiconductors, but are of the indirect intermediate variety. But in straight gap semiconductors, the maximum energy level of the valence band and the minimum energy level of the conduction band do not occur simultaneously with electrons. Therefore, during the recombination of electrons and holes, electrons migrate from the conduction band to the valence band, and the momentum of the electron band will be changed.

Advantages and disadvantages

Like any device, the LED also has a number of its own features, main advantages and disadvantages.

Main advantages look like this:

Among the shortcomings the following can be noted:

Lighting devices using LEDs have been on a triumphal march in recent years. On store shelves there is a large selection of Chinese LED flashlights, at a price not much higher than the cost of the batteries included in them, which shine brighter and longer than their counterparts with light bulbs inside. Why did the LED find itself in such an advantageous position?

For those who are not in the know: an LED is a semiconductor device in which electric current is converted directly into light radiation. A diode - that is, it is capable of passing current only in one direction (see the article How a diode works) By the way, in English an LED is called a light emitting diode, or LED.

The LED consists of a semiconductor crystal on a non-conducting substrate, a housing with contact leads and an optical system. To increase durability, the space between the crystal and the plastic lens is filled with transparent silicone. The aluminum base serves to remove excess heat. Of which, I must say, a very small amount is released.

Glow in a semiconductor crystal occurs when electrons and holes recombine in the region of the pn junction. The pn junction region is formed by the contact of two semiconductors with different types of conductivity. To do this, the near-contact layers of the semiconductor crystal are doped with different impurities: acceptor impurities on one side, donor impurities on the other.

For a pn junction to emit light, the band gap in the active region of the LED must be close to the energy of visible light quanta. Secondly, the semiconductor crystal must contain few defects, due to which recombination occurs without radiation. To meet both conditions, often one pn junction in a crystal is not enough, and manufacturers are forced to manufacture multilayer semiconductor structures, so-called heterostructures.

Obviously, the more current passes through the LED, the brighter it shines, since the greater the current, the more electrons and holes enter the recombination zone per unit time. However, due to the internal resistance of the semiconductor and the p-n junction, the diode heats up and, at high current, can burn out - the supply wires will melt or the semiconductor itself will be burned out.

Unlike incandescent lamps, electric current in LEDs is converted directly into light radiation, with little heat loss. As a result, LEDs are several orders of magnitude more economical and are indispensable in those devices where heating is unacceptable. A special feature of the LED is its emission in a narrow part of the spectrum. For this reason, designers fell in love with it for the production of illuminated advertising and room decoration. UV and IR radiation are generally absent from LEDs. The LED has high mechanical strength and reliability. The service life of an LED reaches 100 thousand hours, which is almost 100 times longer than that of an incandescent light bulb, and 5 to 10 times longer than that of a fluorescent lamp. Finally, the LED is a low-voltage electrical device, and therefore safe.

The only drawback of the technology is its high cost. At the moment, the price of one lumen emitted by an LED is 100 times higher than the lumen emitted by an incandescent lamp. However, manufacturers predict a decrease in this indicator by 10 times in the coming years.

LEDs based on gallium phosphide and arsenide, emitting in the yellow-green, yellow and red regions of the spectrum, were developed back in the 60s - 70s of the last century. They were used in light indicators, displays, dashboards of cars and airplanes, advertising screens, and various information visualization systems. In terms of light output, LEDs have surpassed conventional incandescent lamps. They also surpassed them in durability, reliability, and safety. For a long time there were no blue, blue-green and white LEDs. The color of the LED depends on the band gap in which electrons and holes recombine, that is, on the semiconductor material and dopant impurities. The “blue” the LED, the higher the energy of the quanta, which means the larger the bandgap should be.

It was possible to produce blue LEDs based on semiconductors with a large band gap - silicon carbide, compounds of group II and IV elements or nitrides of group III elements. However, SiC-based LEDs turned out to have too low efficiency and low quantum yield (that is, the number of emitted quanta per recombined pair). LEDs based on solid solutions of zinc selenide ZnSe had a higher quantum yield, but they overheated due to high resistance and were short-lived. The first blue LED was produced using gallium nitride films on a sapphire(!) substrate.

Quantum yield is the number of light quanta emitted per recombined electron-hole pair. A distinction is made between internal and external quantum efficiency. Internal - in the pn junction itself, external - for the device as a whole (after all, light can be lost “along the way” - absorbed, scattered). The internal quantum efficiency for good crystals with good heat dissipation reaches almost 100%, the record external quantum efficiency for red LEDs is 55%, and for blue LEDs - 35%. External quantum efficiency is one of the main characteristics of LED efficiency.

White light from LEDs can be obtained in several ways. The first is to mix colors using RGB technology. Red, blue and green LEDs are densely placed on one matrix, the radiation of which is mixed using an optical system, such as a lens. The result is white light. The second method is that three phosphors are applied to the surface of an LED emitting in the ultraviolet range (there are some), emitting blue, green and red light, respectively. Based on the principle of a fluorescent lamp. The third method is when a yellow-green or green-red phosphor is applied to a blue LED. In this case, two or three radiations are mixed, forming white or close to white light.

Each method has its own advantages and disadvantages. RGB technology in principle allows not only to obtain white color, but also to move along the color diagram as the current changes through different LEDs. This results in a whole lighting complex that can be controlled manually or through a program. Such effects are widely used by designers and manufacturers of Christmas tree garlands and similar devices. In addition, a large number of LEDs in the matrix provides a high total luminous flux and high axial luminous intensity. The disadvantage of the system is the uneven color in the center of the light spot and at the edges. In addition, due to uneven heat removal from the edges of the matrix and from its middle, the LEDs heat up differently, and, accordingly, their color changes differently during the aging process - the total color temperature and color “float” during operation. This unpleasant phenomenon is quite difficult and expensive to compensate for. White LEDs with phosphors are significantly cheaper than RGB LED matrices (calculated per unit of luminous flux) and provide good white color. Their disadvantages: firstly, they have less light output than RGB matrices due to the conversion of light in the phosphor layer; secondly, it is quite difficult to accurately control the uniformity of phosphor application in the technological process and, consequently, the color temperature; and finally, thirdly, the phosphor also ages, and faster than the LED itself.

The industry produces both LEDs with phosphor and RGB matrices - they have different areas of application. A conventional LED used for indication consumes from 2 to 4 V DC voltage at a current of up to 50 mA. The LED used for lighting consumes the same voltage, but the current is higher - from several hundred mA to 1 A in the project. In an LED module, individual LEDs can be connected in series and the total voltage is higher (usually 12 or 24 V).

When connecting an LED, the polarity must be observed, otherwise the device may be damaged. The breakdown voltage is usually more than 5 V for a single LED. The brightness of an LED is characterized by luminous flux and axial luminous intensity, as well as by the directional pattern. Existing LEDs of various designs emit solid angles from 4 to 140 degrees. Color, as usual, is determined by chromaticity coordinates and color temperature, as well as the wavelength of the radiation.

The brightness of the LEDs is adjusted not by reducing the supply voltage, but by the so-called pulse width modulation (PWM) method. This requires a special control unit. The PWM method consists in the fact that not a constant, but a pulse-modulated current is supplied to the LED, and the signal frequency should be hundreds or thousands of hertz, and the width of the pulses and pauses between them can vary. The average brightness of the LED becomes controllable, while at the same time the LED does not go out.

LEDs are quite durable, but high-power signal LEDs have a shorter lifespan than low-power signal LEDs. However, it currently amounts to 20 - 50 thousand hours. Aging is expressed primarily in a decrease in brightness and a change in color.

The emission spectrum of an LED is close to monochromatic, which is its fundamental difference from the spectrum of the sun or an incandescent lamp. Serious studies have never been carried out on the effect of such lighting on vision.

Translated from English, the abbreviation LED literally means “a diode that emits light.” This is a semiconductor device capable of transforming electric current into a simple device, the design of which is quite different from the lighting products we are used to (incandescent lamps, discharge lamps, fluorescent lamps, etc.).

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

History of origin

When considering why LEDs work, you should study the history of their origin. For the first time such a device was created in 1962 by scientist N. Holonyak. It was a monochrome glow. It had a number of disadvantages, but the technology itself was considered promising.

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

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

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

LED device

To understand how a spot LED works, you need to take a closer look at its design. This lighting device, according to representatives of the Association for the Development of the Optoelectronic Industry and the Department of Energy, will soon become the most popular source of lighting in ordinary homes, offices, and institutions.

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

To increase the service life of the device, the space between the plastic lens and the crystal itself was filled with a transparent silicone component. An aluminum base is used to remove excess heat. This is a common device of a modern diode. During operation, it emits relatively little. This is also an advantage of the device.

Principle of operation

When considering how an 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 junction. This is due to the different principles of conductivity of the illuminator components. One semiconductor has an excess of electrons, and the other has an excess of holes.

Through the doping process, the holey material is enriched with negative charge carriers. If a current is applied where the semiconductors are enriched with opposite charges, a forward bias will result. Electricity will flow through the junction of these two materials.

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

LED color

Various semiconductor materials are used to create diodes. This determines the color that the presented device emits when operating. Different materials are capable of sending waves of different lengths into space. This allows the human eye to see one or another color of the visible spectrum.

When studying how an LED works, you should consider semiconductor materials. Previously, gallium phosphide and ternary compounds GaAsP and AlGaAs were used for similar purposes. In this case, the device could send red, yellow-green

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

Mixing colors

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

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

However, in addition to the presented technology, it is possible to obtain a white glow by connecting a short-wave radiation diode (ultraviolet, blue) together with a yellow phosphor-type coating. When yellow and blue photons are combined, the result is white light.

Production

To understand how many volts LEDs operate at, it is necessary to consider the production of these devices. First of all, it should be noted that devices with an RGB matrix are more expensive than phosphor forms. Moreover, the latter make it possible to achieve high quality lighting.

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

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

Brightness boost

Considering the question of what voltage LEDs operate from, 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 housing, 15-20 light elements will need to be installed.

Diodes with enhanced brightness can carry a power of up to 240 W. To ensure normal illumination, 4-8 pieces of such elements will be required. There are devices on sale that are capable of fully illuminating rooms, outdoor advertising, shop windows, etc. Some strips are created to provide lighting of medium or low intensity.

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

Glow control

There are a huge number of options for the equipment presented. There are LEDs that operate on batteries (for example, in flashlights), powered 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. To reduce the glow intensity, pulse width modulation (PWM) is used. In this case, a control unit is purchased.

The presented method involves applying a pulse-modulated current to the diode. The signal frequency reaches thousands of hertz. The width of pulses and pause intervals can be changed. In this case, you can control the glow of the device. In this case the diode will not go out.

Durability

Diodes are considered long-lasting devices. This is due to their design. However, if the LEDs on the lamp do not work, their service life may have expired. This can be determined by the intensity of the glow and color change.

Experts also note that the service life of low-power devices is much longer. But even in the brightest strips or lamps, diodes are guaranteed to operate for 20-50 thousand hours. Since they do not have fragile structural elements, mechanical impacts are more likely not to harm such illuminators.

By studying how an LED works, you can understand the design principle of this device, as well as its operational characteristics. This equipment is considered to be the illuminators of the future generation.