The Principle of LED Displays

The application of large screen LED display has penetrated into all walks of life, in order to achieve orderly and quick display control of hundreds or thousands of LED dot matrix pieces, LED display is constantly being updated and iterated. So what is the principle and composition of LED displays?

1. Basic principle of LED display
Take LED (Light Emitting Diode) as the basic light-emitting element (pixel), through the control circuit and drive circuit to control the brightness of each pixel, to show a variety of information requested by people.
Four major components: light-emitting materials (LED), driving circuit, control circuit, frame structure.

2. Working principle of LED display
The basic working principle of LED display is dynamic scanning. Dynamic scanning is divided into line scan and column scan, from which line scan is more common. Line scan is also divided into 8 lines of scanning and 16 lines of scanning.
In the line scan mode of operation, each LED dot matrix chip has a set of column drive circuit, which has a latch or shift register used to latch the word mode data to be displayed. In the line scan mode of operation, the same row of LED dot matrix chip of the same name line control pins are connected in parallel on a line, a total of 8 lines, finally connected in a line drive circuit; line drive circuit must also have a latch or shift register used to latch the line scan signal.
LED display driver circuit is generally controlled by the microcontroller, form which 51 series is the most common. The content of the display is often stored in the external data memory of the microcontroller in the form of word patterns.

The process of controlling the LED display by microcontroller is read first and then write.

According to the order of the LED dot matrix piece on the screen, the microcontroller in order to the first row of the first LED dot matrix piece of the data, followed by the first row of the second piece, the third piece ...... until the last piece are written after the word mode data, and then the date of this row scan signal, so you can light up the relevant light-emitting diodes.
Then light up the rest of the rows in the same way as the 1st row. After lighting, delay a period of time, and then black screen, so that the microcontroller completed a line of LED display scanning control.
The process is also basically the same for the scanning control of the 2nd line of the LED display by the microcontroller, the scanning control of the 3rd line ...... until the scanning control of the 8th line. After the control process are completed, LED display will be able to appear 1 frame image of the complete display.

Although according to this way of working which is lit line by line and each time only one line is lit, to ensure that each line can be lit more than 50 times per second and the refresh frequency is higher than 50 Hz. Finally, because of human visual inertia, the image that people see on the LED display is still a full screen stable image.