How does ordinary LED street light work, what is the working principle of street light?

Ordinary LED street light is a street light that uses LED as a light source, and its working principle is similar to that of ordinary LED lamps. Here's how ordinary LED street lights work.

The main components of ordinary LED street lights include LED light source, drive circuit and heat dissipation system. The LED light source is the core component of the street lamp, which is composed of multiple LED chips, each chip has positive and negative electrodes. The drive circuit is responsible for converting electrical energy into current and voltage suitable for LED operation to ensure the normal operation of LED.

The heat dissipation system is used to dissipate the heat generated by the LED to ensure the long-term stable operation of the LED.

When the LED street light is connected to the power supply, the drive circuit will convert the alternating current to direct current, and adjust the current and voltage to the range suitable for the LED operation. The positive and negative poles of the LED chip are connected to the positive and negative poles of the drive circuit, and when the current passes through the LED chip, the semiconductor material in the chip will recombine the electrons and holes, generating energy and releasing light. This process is called the electroluminescence effect.

The light intensity and color of LED street lights are mainly determined by the material and structure of the LED chip. Different materials and structures can produce different spectra, resulting in different colors and brightness. There are two main types of LED street lights: white LED and color LED.

White LEDs are mainly composed of blue LED chips and yellow phosphors, which excite yellow phosphors through blue light to emit yellow light, and then mix with blue light to form white light. Color LEDs are different colors through a combination of different phosphors and LED chips.

LED street lights have many advantages over traditional street lights, such as high efficiency and energy saving, long life, good shock resistance, etc. However, LED street lights also have some problems, such as light decay, unstable color temperature, etc. In order to solve these problems, the research and development and improvement of LED street lights are still ongoing.

In short, the working principle of ordinary LED street lights is to convert electrical energy into current and voltage suitable for LED work through the driving circuit, so that the LED chip undergoes electroluminescence effect and produces light. The light intensity and color of LED street lights are mainly determined by the material and structure of the LED chip.

The core part of the light-emitting diode is a wafer composed of p-type semiconductors and n-type semiconductors, and there is a transition layer between the p-type semiconductor and the n-type semiconductor, called the p-n junction. In the PN junction of some semiconductor materials, when the injected minority carriers are recombined with the majority carriers, the excess energy is released in the form of light, so that the electrical energy is directly converted into light energy.

The current passes through the rectifier, and the bulb is instantly started at high voltage through the trigger, and the capacitor is replenished.

The light-emitting device uses LEDs, and that's it, it's just a troublesome point for heat dissipation.

Street lights work by converting electrical energy into light energy to provide illumination at night. Here's a detailed look at how street lights work.

Street lights are mainly composed of light poles, lamp heads, lamp shades, power supplies and control systems. The power supply provides electrical energy for the street lights, and the control system controls the switching and brightness of the street lights.

The lamp head of the street lamp usually uses a high-pressure sodium lamp or LED lamp. A high-pressure sodium lamp is a type of gas-discharge lamp that works by producing light through the discharge of high-pressure sodium vapor. The bulb of a high-pressure sodium lamp has two electrodes inside, and when an electric current passes through the electrodes, the high-pressure sodium vapor between the electrodes discharges, producing an intense yellow light.

High-pressure sodium lamps have the characteristics of high brightness, high efficiency and long life, and are suitable for street lighting.

LED lamp is a semiconductor light-emitting diode, which works by recombining electrons and holes near the PN junction to release energy and produce light when an electric current is passed through a semiconductor material. LED lamps have the characteristics of high brightness, low energy consumption and long life, and gradually replace the traditional high-pressure sodium lamps.

The power supply for street lights is usually AC power, which transmits electrical energy to the light pole through a cable. The power supply converts the alternating current into direct current that is suitable for the operation of the street lamp and provides a stable voltage and current.

The control system is an important part of the street light, which can realize the switching and brightness adjustment of the street light. The control system usually includes a light switch and a time controller. The light control switch can automatically turn on and off the street lights according to the light intensity, and when the light intensity is lower than a certain threshold, the street lights will be automatically turned on; When the light intensity is above a certain threshold, the street lights are automatically turned off.

The time controller can control the switching of street lights on and off according to a preset schedule, such as turning on street lights during specific hours of the night.

To sum up, street lights work by converting electrical energy into light energy to provide illumination at night. The power supply provides electrical energy for the street lamp, and the lamp head uses a high-pressure sodium lamp or LED lamp to convert the electrical energy into light energy, and the control system realizes the switching and brightness adjustment of the street lamp. These components work together to enable street lights to provide safe and comfortable illumination at night.

Series circuit, independent power supply.

In 998, the development of LED that emits white light was successful. This LED is made by encapsulating a GaN chip with yttrium aluminum garnet (YAG). The GaN chip emits blue light (P=465nm, WD=30nm), and the YAG phosphor containing CE3+ made by high-temperature sintering emits yellow light after being excited by this blue light, with a peak value of 550nm.

The blue LED substrate is mounted in a bowl-shaped reflective cavity and covered with a thin layer of resin mixed with YAG, about 200-500 nm. Part of the blue light emitted by the LED substrate is absorbed by the phosphor, and the other part of the blue light is mixed with the yellow light emitted by the phosphor to obtain white light. Now, for the Ingan YAG white LED, by changing the chemical composition of the YAG phosphor and adjusting the thickness of the phosphor layer, various colors of white light with a color temperature of 3500-10000K can be obtained.

The luminous color and luminous efficiency of LED are related to the materials and manufacturing processes of making LEDs, and there are three widely used types: red, green and blue. Due to the low working voltage of LED (only, it can actively emit light and has a certain brightness, and the brightness can be adjusted by voltage (or current), and it is resistant to shock, vibration and has a long life (100,000 hours). Depending on the material used to make LEDs, photons with different energies can be generated, which can control the wavelength, also known as the spectrum or color, of the light emitted by the LEDs.

The material used in the first LED in history was arsenic (AS) gallium (Ga), and its forward PN junction voltage drop (VF, which can be understood as the lighting or operating voltage) is, and the light emitted is the infrared spectrum. Another commonly used LED material is gallium phosphide (P) (Ga), which emits green light due to a forward PN junction voltage drop. Based on these two materials, the early LED industry used the GaAS1-XPX structure, which could theoretically produce LEDs of any wavelength from infrared to green, with the subscript X representing the percentage of phosphorus replacing arsenic.

Generally, the wavelength color of the LED can be determined by the PN junction voltage drop. Among them, the typical ones are red LEDs, orange LEDs, yellow LEDs, etc. Because the three elements of gallium, arsenic, and phosphorus are used in the manufacturing, these LEDs are commonly known as three-element light-emitting tubes.

GaN (gallium nitride) blue LEDs, GAP green LEDs, and GAAS infrared LEDs are called two-element light-emitting tubes. At present, the latest process is the four-element LED made of Algainn, which mixes aluminum (Al), calcium (Ca), indium (In) and nitrogen (N), which can cover all visible light and part of the ultraviolet light spectral range.

So it's the material and the current that makes the LED that determines the light wave that emits light.

LED (lightemittingdiode), light-emitting diode, is a solid-state semiconductor device that can directly convert electricity into light. The "heart" of LED is a semiconductor wafer, one end of the wafer is attached to a bracket, the negative pole connected to the power supply is connected, and the other end is connected to the positive pole of the power supply, so that the entire wafer is encapsulated by epoxy resin. A semiconductor wafer is made up of two parts, one is a p-type semiconductor, in which holes dominate, and the other end is an n-type semiconductor, which is mainly electrons here.

When these two semiconductors are connected, a p-n junction is formed between them. When an electric current is applied to the wafer through the wire, the electrons are pushed to the p-region, where the electrons recombine with the holes, and then emit energy in the form of photons, which is the principle of LED light-emitting, and its internal structure is shown in Figure 2-9.

Figure 2-9 Light-emitting diode and its internal structure.

1.Lead frame 2Anode rod 3Wedge bracket 4Transparent epoxy resin encapsulation chip 6There is a cathode rod for the launch bowl.

The LED light is a light-emitting diode, which has the characteristics of a diode, and has a positive and negative electrode, but it is reversed, and the current cannot be turned on, and the light will not be lit. Its working voltage is, where the red light is, the white light, the green light, and the blue light are generally.

When the LED is working, it must be limited or constant, otherwise it will burn out. LED operation is non-linear and has diode characteristics. For small power, add a current limiting circuit to do.

For high power, you must use a constant current power supply, it doesn't matter if the voltage is higher, as long as the current is appropriate.

High-power LEDs must consider heat dissipation, otherwise they will burn out, and low-power ones can not be used.

LED works, just consider the current, it doesn't matter if the voltage is high. For example, a 2V low-power red LED is connected in series with a 200K resistor, which is connected to 1,000 volts of direct current, and it will not burn out. However, the withstand voltage of the LED reverse is not high, and if it is reversed, more than ten volts can be burned off, of course, it will definitely be broken when connected to 1000 volts of alternating current.

Smart LED lights are the perfect integration of LED with sensing technology and control technology, so that energy saving reaches a new height. When someone enters the detection range of the sensor, the smart channel light will automatically turn on, and when the person leaves, the light will be turned off after the delay OFF time. There are also some smart bulbs that control the brightness, switch and color of the bulb through the remote control, etc.

1. Basic concepts of optics.

1 Luminous flux

Definition The magnitude of the light energy perceived by the human eye is called luminous flux and is usually represented by letters The unit of luminous flux is lumens lm

2 Luminous intensity. iv

Defines the visible light emitted by a point light source in all directions in a certain direction at a solid angle in units. d.

The luminous flux is. d then the luminous intensity of the point light source in that direction. iv to iv d d

Luminous intensity. IV unit Candela CD 1000mcd 1cd3 light emissivity. m

Define the magnitude of the luminous flux emitted by the light source per unit luminous area m d da

The unit of light emittance is lux lx( 1lm m2)4 illuminance. e

Definition The amount of luminous flux received per unit of irradiated area

e＝dφ/da

The unit of illuminance is lux lx( 1lm m2)5 brightness. l

Describes the spatial distribution of visible light emitted by a luminaire with a finite size by defining the unit luminous area. The luminous intensity of da in the direction. iv is flat with the unit area perpendicular to that direction.

Projection on the face. Cos da ratio

l＝iv/cosθda

The unit of brightness is candela square meter cd m2

6 Luminous efficiency

Define the ratio of the luminous flux emitted by the light source to the electrical power p consumed by the light source p

The unit of luminous efficiency is lumens watts lm w

Incandescent lamp luminous efficiency .15 lm W LED achievable. 100 lm w (laboratory value).

The efficiency of white LEDs is 25lm W

7 Color temperature. A blackbody is an object that absorbs all the energy of any wavelength that radiates to its surface at any temperature

The light emittance m of a black body rises extremely rapidly as the temperature rises

m black = t4

It's too cumbersome to talk about professionally, and that's how the current goes from the positive electrode to the negative electrode, and the resulting current glows and lights up. LED is the abbreviation of light emitting diode, the Chinese name "light-emitting diode" its luminous principle is followed.

The principle of luminescence is similar to that of laser light.

There are many energy levels for electrons in an atom, and when an electron jumps from a higher energy level to a lower energy level, the energy of the electron decreases, and the reduced energy is converted into photons that are emitted. A large number of these photons are lasers.

LEDs work in a similar way. However, the difference is that LEDs do not emit light through the electron transition inside the atom, but by adding voltage to the ends of the PN junction of the LED, so that the PN junction itself forms an energy level (in fact, a series of energy levels), and then the electrons jump on this energy level and produce photons to emit light.