The basic structure and working principle of LED traffic lights

Lamp shell structure
The shell structure of LED traffic lights mainly plays a protective and supporting role to ensure the stable operation of the lamps under various climatic conditions. The shell is usually made of high-strength engineering plastics or aluminum alloy materials, and has the ability to be waterproof, dustproof and UV-resistant. The surface of the shell is generally sprayed or anodized to improve its weather resistance.
The shell is designed with a heat sink or ventilation structure to help the heat dissipate quickly and prevent the temperature rise from having an adverse effect on the LED light source. A transparent protective panel is installed at the front end, generally made of polycarbonate material, with good light transmittance and impact resistance, which can ensure the light effect while improving safety.

LED light source module
LED is the luminous core of the entire traffic light. The LED light source adopts the principle of semiconductor light emission, and releases energy through the recombination of electrons and holes, which is converted into visible light. The LED light source can emit red, yellow and green light respectively, meeting the three-color display requirements of traffic lights.
The LED module is usually composed of multiple high-brightness LED chips arranged in an array, and an optical lens is used to enhance the focusing effect, so that the light beam has a certain directionality. Each color light source has its own exclusive circuit control and dimming mechanism to ensure that the light intensity meets national standards.
In specific applications, the emission wavelengths of different color LEDs are as follows:

LED Emission Wavelengths by Signal Color

LED light sources not only have fast response speeds, but also have long service lives. Most products have a design life of more than 50,000 hours. Due to its fast lighting speed, it helps to improve the efficiency of traffic command execution.

Optical lens and reflective structure
The optical system in LED traffic lights consists of optical lenses and reflectors. The lens can be designed at different angles according to the purpose of the lamp to adjust the light angle and increase the visible range. The reflective structure is used to collect and enhance the light from the LED, so that it is concentrated in a specific direction to improve the light efficiency. Some high-end lamps are also equipped with a secondary optical system, which further controls the spot size, brightness uniformity and visible distance through a multi-layer optical structure to enhance performance in rainy and foggy weather.
The surface generally adopts a honeycomb or optical grid texture to reduce the "false signal" interference caused by direct sunlight reflection. This design helps to improve the recognition accuracy of LED signal lights in complex outdoor lighting environments.

Control circuit and drive system
The normal operation of LED traffic lights depends on stable control circuits and drive power systems. The control circuit is responsible for receiving instructions from the upper signal controller, controlling the on and off states of different color LEDs according to the set time logic, and realizing the signal switching function.
The drive power supply provides constant current output to keep the current of the LED chip stable and prevent brightness changes or light decay due to voltage fluctuations. Modern LED drivers are mostly equipped with short-circuit protection, overheating protection, surge protection and other functions to improve the stability and safety of the system.
The control circuit will also be connected to the centralized control platform to realize remote monitoring, fault alarm, self-test and other functions. In the intelligent transportation system, the control unit can also be connected to cameras, flow detectors and other equipment to realize real-time scheduling.

Heat dissipation structure and temperature control system
Although the LED light source is highly efficient, it will still generate a certain amount of heat during continuous operation. If the heat cannot be effectively dissipated, it will affect the chip life and light performance. For this reason, LED traffic lights are generally equipped with active or passive heat dissipation structures.
Common heat dissipation methods include aluminum substrate heat conduction, fin-type shell heat dissipation, natural convection ventilation, etc. Among them, the aluminum substrate, as the carrier of the LED chip, not only provides mechanical support, but also has good thermal conductivity, which helps to quickly conduct heat.
Some high-end products are also equipped with intelligent temperature control modules, which monitor the temperature of the LED module in real time through temperature sensors, and dynamically adjust the drive current to prevent overheating.

Power module and wiring system
The power module is the energy supply core of the entire system. It converts the mains power (such as AC 220V) into the DC constant current voltage (such as DC 12V/24V) required by the LED and provides stable output. High-quality power modules should have high conversion efficiency, low fluctuations, and good anti-electromagnetic interference capabilities.
In order to achieve fast connection and fault troubleshooting, LED signal lights are usually equipped with modular terminal blocks, quick-plug interfaces or waterproof connectors. The electrical connection of the entire system needs to comply with national safety regulations, such as insulation level, protection level, lightning protection level, etc.

Brief description of the working principle process
The basic working principle of LED traffic lights can be summarized as: power supply → constant current of the drive module → control circuit receives instructions → control LED color switching → optical system light guidance → heat dissipation system maintains stable operation.
The following is a simplified workflow chart:

Simplified Workflow of LED Traffic Signal Lights

The entire system can achieve 24-hour continuous operation and periodically change the signal display by setting the time program.

Intelligent functions and expansion interfaces
Modern LED traffic lights are no longer just a single light-emitting device, they are also gradually integrated into the intelligent transportation system. Through the networking of the controller and the central platform, the following extended functions can be realized:
Remote control: remote start and stop and state switching through the communication module.
Data feedback: real-time transmission of operating status, voltage, current, brightness and other parameters.
Automatic dimming: automatically adjust the LED output according to the ambient brightness to improve energy saving.
Fault alarm: automatically report fault information when the chip is damaged or the power supply is abnormal.
This type of intelligent function is realized through the built-in MCU (micro control unit) and communication modules (such as GPRS, NB-IoT), which not only improves the flexibility of the transportation system, but also facilitates later management and maintenance.