Now the application of large screen LED display is more and more extensive. In order to achieve orderly and fast display control of hundreds and thousands of LED lattices, people have mobilized a lot of brains. When people in the LED display industry gather together, it is easy to talk about the products of the LED display screen and directly say some terminology. At this time, if you don't understand anything, is it embarrassing to chat like this? Share with you the basic knowledge of the most complete LED display project and common terminology explanation so that you can instantly change from a small white LED display to understand Pingdi!
(Warm reminder, nowadays English abbreviations are used more and more, and there are more and more ambiguities. We must remember that don't make jokes.)
I. Basic Principles of LED Display Screen
The LED is short for lighting emitting diode, it is a kind of self-light display unit, with Red, Glue, Green three colours.
A LED module or lighting unit is made of LED Lamps, PCB, Suit and Cables.
II. Working Principle of LED Display Screen
In line scan mode, each LED lattice chip has a set of the column drive circuit, which must have a latch or shift register to lock the font data of the content to be displayed. In line scanning mode, the same row control pins of the same row of LED dot matrix are connected to one line, totally eight lines, and finally connected to a row driving circuit. There must be a latch or shift register in the row driving circuit to lock the line scanning signal. (LED screen elementary knowledge)
The row driving circuit and row driving circuit of LED display screen are generally controlled by a single chip computer. The commonly used single chip computer is MCS51 series. The contents displayed on the LED display screen are generally stored in the external data memory of the single chip computer in the form of fonts, which are 8-bit binary numbers.
The control process of the single chip computer to the LED display screen is read first and then write. According to the arrangement order of LED dot matrix on the screen, the MCU first drives the latch on the first row of LED dot matrix, writes the font data read from the external data memory, and then on the second and third slices... Up to the end of this row, after the font data is written, the SCM writes the line scan signal to the row-driven latches in this row, and the light-emitting diodes related to the font data in the first row are lit up. Then row 2, row 1, row 3, row 1... Until the first row of the last row is lit. After the first line of each row is lit up, it is delayed for a period of time, and then the black screen, so that the single-chip computer can complete the one-line scanning control of the LED display screen. (LED display elementary knowledge)
SCM scanning control of the second line and the third line of LED display screen... Up to the scanning control of line 8, the process is the same as that of line 1. After the control process of all 8 lines is completed, the LED display screen also completes the complete display of 1 frame image.
Although in this way, the LED display screen is lit one line by one, only one line at a time, but as long as we ensure that each line can be lit more than 50 times per second, that is, refresh frequency is higher than 50 Hz, then due to human visual inertia, the image seen on the LED display screen is still a stable full-screen image.
III. Basic Composition of LED Display Screen (LED product training knowledge)
1. Asynchronous screen:
Generally, it consists of display unit board (module), strip screen card, switching power supply and HUB board (optional). Connecting with a computer through the serial port line, the display text can be changed, and then the computer can be disconnected from work.
2. Synchronization screen:
Synchronization screen system is relatively complex, and the system can be large or small. Generally, it consists of a computer, DVI graphics card, data transmission card, synchronization data receiving the card, HUB board, network cable, LED display screen and so on. The system always needs an on-line computer to work, displaying the image and text on the computer on the large LED screen.
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