LED is an abbreviation consisting of the initials light emitting diode. As the name suggests, led is a diode. As we know, the diode is a two-legged semiconductor circuit element that allows the current to pass in only one direction.
How does the LED work?
Like other diodes, the LED has two different types of semiconductor substances, p-type and n-type. The P-type semiconductor has positive load carriers, while the n-type semiconductor has negative load carriers. In this way, it is possible to pass electric current through the diode only in the direction of the cathode from the anode.
The same is true with the LED. Unlike standard diodes, electron exchange in LEDs at the point where p and n type semiconductors meet causes light to form. This phenomenon is called electroluminesceces.
History of LED;
- In October 1962, Texas Instruments acquired the first commercial LED, the SNX-100.
Produced. The red LEDs produced were used in signals and indicators.
- In 1972, the first radial sheath LEDs were produced.
- The 80s and 90s were a turning point for LEDs. During this period, it was produced in yellow, green, blue, white LEDs as well as red LEDs.
- 1994 Started to be used in traffic lights.
- After 2000, it was used in vehicles because it was not affected by tremors.
- Since 2010, it has been used for lighting in homes.
LeDs were first able to emit enough light to be used in the power and status indicators of electronic devices. Today, thanks to the development of technology, LEDs are used in many areas such as indoor and outdoor lighting solutions, car headlights, billboards, television and LCD screen lighting. LCD screens cannot create their own lights due to their structure. For this reason, there is a lighting system behind the LCD panels. Previously, cold cathode lighting called CCFL was used as panel lighting. However, since such lighting solutions were lineually structured, just like fluorescent bulbs, they could not fully illuminate the screen in a homogeneous way. In addition, this type of lighting consumed more power than LEDs.
In this type of panel lighting, there are two different solutions: D-LED (direct LED) and E-LED (edge, edge LED). In the D-LED, leDs are arranged under the entire panel, while in the E-LED solution, similar to ccfl, a rod is illuminated only from the edges and the panel is illuminated with this light.
LeDs have many types according to their usage area, size, sheaths and, of course, the light color they create. The most well-known of these are the 5mm LEDs that we use frequently in our electronic circuits. This type of LEDs are available in a variety of colors such as red, white, green, blue and yellow. In addition, most infrared LEDs used in television remote controls fall into this category.
What is Infrared LED?
The light is basically radiation, energy, emitted from place to place. The part of the light that comes across with different wavelengths between 380 nm and 780 nm is expressed as the visible light spectrum . Over thousands of years of evolution, our eyes have evolved to detect these wavelengths and take shape today.
The light in the visible light spectrum is divided into colors according to different wavelengths. In this sense, close wavelengths of 780 nm and above are called infra-red light in the meaning of "beyond red" and technologies such as cameras and controls are also used.
These applications, which are usually used as vertices with wavelengths of 850 nm and 940 nm, are becoming more and more important with the increase in efficiency of LEDs.
What is RGB LED?
(Red-Green-Blue) LEDs are a type of LED that includes red, green and blue colors. It is often used especially in animation and lighting systems. RGB LEDs have specific ranges for each color. Thanks to these ranges, it is possible to obtain many colors. With the help of a control algorithm, the voltage of the color ranges related to it is regulated, allowing it to burn completely, completely extinguish or partially burn. There are two types of RGB LEDs: common anode and common cathode. Therefore, we must adjust our circuit diagram correctly according to the RGB LED that we also use. Common cathode LEDs are activated by positive edge triggering of the PWM signal, while common anode LEDs have the opposite.
What is Strip LED?
Strip LEDs mostly have current limiting resistors suitable for working at 12V voltage with SMD type LEDs on flexible PCB. In this way, they can be easily operated with power supplies such as a simple 12V transformer, car battery, LiPo battery.
Ribbon LEDs can be monochrome or RGB and addressable type. This is all about the type of LED used in the strip. For example, it is possible that we can adjust the color of a strip LED consisting of standard RGB LEDs, but the color of the entire strip will be the same. However, we can check the color and brightness of each LED on a strip of addressable LEDs with the WS2812 chip.
What is a Power LED?
High power (0.5W and above) LEDs are called power LEDs. This type of LEDs are preferred in lighting applications rather than works such as power and status indicators in electronic circuits. Since they are used in lighting, focusing light has lenses for most. In addition, such LEDs heat up because they consume high power, so most power LEDs have their own cooling solution.
What is SMD LED?
Unlike the 5mm LEDs we often use on our breadboard and perforated pertinax cards, SMD LEDs are LEDs soldered to the surface of circuit boards. A wide range of SMD LEDs are available for their intended use and size.
SMD LEDs have active light-emitting regions called "chips". Generally, single-chip and 3-chip LEDs are preferred in strip LEDs on the market.
What is COB LED?
This abbreviation, which consists of the initials of the words Chip-on-Board, represents LEDs produced by combining the core of multiple LEDs into a single plate.