Construction and Display Principles of LED Screens

LED displays are becoming increasingly common in our daily lives, and you are probably familiar with it to some extent. However, few people have a detailed understanding of LED displays. Let's learn about it with the help of IoT technology.

Structure of LED displays

1) Metal structure frame: it constitutes the internal framework, carrying various circuit boards such as display units or modules and switch power supplies.

2) Display unit: It is the main part of the LED display, consisting of LED lights and driving circuits. The indoor screen is a unit display board of various specifications, and the outdoor screen is a module box.

3) Main controller: Its function is to buffer the input RGB digital video signal, transform the grayscale, reorganize it, and generate various control signals.

4) Switch power supply: It converts AC power into various DC powers and supplies them to various circuits.

5) Transmission cable: The display data and various control signals generated by the main controller are transmitted to the screen body via twisted pair cables.

6) Scanning controller: The function of this circuit board is data buffering, generating various scanning signals, and duty cycle grayscale control signals.

7) Special display card and multimedia card: In addition to the basic functions of a computer display card, it also outputs digital RGB signals and row, field, and blanking signals to the main controller. The multimedia card can also convert analog video signals into digital RGB signals.

8) Other signal sources and their external devices, including computers, TVs, Blu-rays, DVDs, VCDs, camcorders, etc.

Working principle of LED displays

With the computer as the processing control center, the LED display corresponds to a specific area of the computer monitor window point by point, and the displayed content is synchronized in real-time. The screen mapping position can be adjusted, and the size of the displayed screen can be conveniently selected. The display dot matrix adopts ultra-high brightness LED light-emitting tubes (red and green dual colors), with rich and realistic colors, and supports true color display modes.

Equipped with graphic and three-dimensional animation playback software, it can play high-quality graphics and three-dimensional animations. The display method of the playback software has more than ten forms, including coverage, closing, opening, color alternation, zooming in and out, etc. By using dedicated program editing playback software, information such as text, graphics, and images can be edited, added, deleted, and modified through different input methods such as keyboard, mouse, and scanner. The program is stored on the control host or server hard disk, and the program playback order and time achieve integrated alternating playback and can be overlaid on each other. It can also receive video signals from displaying VCRs, DVD players, and other devices.

The LED display usually consists of a main controller, scanning board, display control unit, and LED display body. The main controller obtains the brightness data of each pixel on the entire screen from the computer display card and allocates it to several scanning boards. Each scanning board is responsible for controlling several rows (columns) on the LED display screen. The LED display signal on each row (column) is transmitted through the serial method through the various display control units in this row, and each display control unit faces the LED display screen directly. The main controller converts the signal of the computer display card into the data and control signal format required by the LED display screen. The function of the display control unit is similar to that of the image display screen, generally composed of shift registers and latch registers with grayscale control functions. However, the scale of video LED displays is often larger, so larger-scale integrated circuits should be used. On the one hand, the scanning board receives the video signal of the main controller, and on the other hand, it transfers the data that belongs to the current level to its various display control units. At the same time, it also transfers the data that does not belong to the current level to the next cascaded scanning board. The scanning board needs to coordinate the differences between video signals and LED display data in space, time, and sequence.