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What is the working principle of the LED display panel?

 - What is the working principle of the LED display panel?

LED display principle

Through the control circuit and drive circuit, the LED (Light Emitting Diode) is taken as a basic light emitting element (pixel) that controls the brightness and extinction of each pixel or its brightness and darkness, allowing the display screen to display a variety of information needed by the user.

What is the working principle of the LED display panel?

Dynamic scanning is the basic working principle of LED displays. Dynamic scanning can be divided into line scanning and column scanning, with line scanning being more common. There are two types of line scanning: 8 line scanning and 16 line scanning.

During line scanning, each LED dot matrix chip is equipped with a group of column drive circuits, and each column drive circuit includes a latch or shift register to lock the font data. For line scanning, the same row control pins of the same row of LED dot matrix chips are connected in parallel to one line, resulting in eight lines, and then the row drive circuit is connected to them; To latch the line scan signal, the line drive circuit must also contain a latch or shift register.

Generally, LED display screens are driven by single-chip microcomputers, such as the 51 series. An external data memory of the microcontroller stores the displayed content as a font.

LED display screens are controlled by single chip microcomputers by reading before writing.

Based on the arrangement order of LED dot matrix chips on the screen, the microcontroller first writes font data to the column drive latch of the first LED dot matrix chip in row 1, then writes line scan signals to the row drive latch of this row after writing font data to the second and third LED dot matrix chips in row 1.

Light the first row of the remaining rows in the same manner. In order to scan the LED screen, the LED screen will be delayed for a period of time before going black.

The microcontroller scans the second and third lines of the LED display screen in the same way until the eighth line is scanned. The LED display screen can display a complete frame of image once the control process has been completed.

In spite of the fact that the LED display is lit line by line, only one line is illuminated at a time, as long as the refresh rate of each line is greater than 50 Hz, the image displayed on the LED display remains a full screen stable image due to human visual inertia.

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