What is the principle of light emitting diode technology?

It is a special diode that uses the collision of electrons and holes in a p-n junction to produce light.

The symbol of the LED circuit diagram is: Ribbon line equiangular triangle is directly opposite the ribbon line vertical thin rectangle, and the upper right corner has an outward emitting lightning bolt sign. Similar to the keyboard tab arrow symbol, add a horizontal line at the vertical line, and then add a lightning bolt sign on the upper right LED power supply commonly used electrical symbols and signs.

It has the same electrical symbol as the infrared light-emitting tube. A light-emitting diode is a type of semiconductor diode that converts electrical energy into light energy. Like ordinary diodes, light-emitting diodes are composed of a p-n junction and are unidirectionally conductive.

Characteristics of light-emitting diodes:1.Forwardness, when the forward voltage is applied, at the beginning of the forward characteristic, the forward voltage is small enough to overcome the blocking effect of the electric field in the PN junction, and the forward current is almost zero, this section is called the dead zone.

This forward voltage, which does not turn the diode on, is called the dead zone voltage. When the forward voltage is greater than the dead zone voltage, the electric field in the PN junction is overcome, the diode is turned on positively, and the current rises rapidly with the increase of voltage.

2.Reverse, when the applied reverse voltage does not exceed a certain range, the current through the diode is the reverse current formed by the drift movement of a few carriers. Since the reverse current is small, the diode is in a cut-off state.

This reverse current is also known as reverse saturation current or leakage current, and the reverse saturation current of the diode is greatly affected by temperature.

Diodes are one of the most common devices in semiconductor devices, and most semiconductors are mostly made of mixed semiconductor materials (atoms and other substances) The LED conductor material is usually aluminium arsenide, in pure aluminium arsenide, all atoms are perfectly bonded to their neighbors, leaving no free electron connection to the defeated current.

Photo-emitting diodes, such as those used in digital display clocks, determine the frequency of the photons, in other words, the color of the light. When all diodes emit light, most are not very efficient. In ordinary diodes, the semiconductor material itself attracts a large amount of light energy.

A light-emitting diode is covered by a plastic bulb that concentrates light in a specific direction.

Light-emitting diode is referred to as LED in English, and its functions are mainly as follows:

1 AC power indicator.

As long as the circuit is connected to a 220V 50Hz AC power supply line, the LED will be lit up to indicate that the power is on. The current limiting resistor R has a resistance value of 220V IF.

2 AC switch indicator.

When the switch is disconnected and the bulb is turned off, the current forms a loop through R, LED and bulb, and the LED is bright, which is convenient for people to find the switch in the dark. At this time, the current curving in the loop is very small, and the bulb will not light up. When the switch is turned on, the bulb is lit and the LED is off.

3 AC power outlet indicator.

A two-color (common cathode) LED is used as an AC power socket indicator circuit. The power supply of the socket is controlled by the switches. When the red LED is on, the socket has no power; When the green LED is on, the socket has power.

4 Fuse holder indicator.

LEDs are used as circuits for the fuse holder indicator of the distribution box of factory equipment. When the fuse tube is intact, the LED does not light up; When the fuse is blown out, the LED will light up to indicate to the user which fuse has been blown so that it can be replaced. This is very convenient for porcelain-core fuses that cannot be observed with the naked eye.

5 DC Power Indicator.