Publisher: Supplier of LED Display Time: 2018-06-08 Views: 2286
The main control box obtains the brightness data of each color of a screen pixel from the display card of the computer, and then redistributes it to several scanning boards, each scanning board is responsible for controlling several rows (columns) on the LED screen, and each row (column) The display control signal of the upper LED is transmitted in a serial manner.
There are currently two ways to serially transmit display control signals:
1. One is to centrally control the grayscale of each pixel on the scanning board. The scanning board decomposes the grayscale value of each row of pixels from the control box (ie, pulse width modulation), and then converts the turn-on signal of each row of LEDs in the form of pulses. (Light is 1, no light is 0) It is serially transmitted to the corresponding LED by row to control whether it is lighted or not. This method uses fewer devices, but the amount of data transmitted serially is larger, because in a cycle of repeated lighting, each pixel needs 16 pulses under 16-level grayscale and 256-level grayscale. 256 pulses, due to the limitation of the operating frequency of the device, generally only the LED screen can achieve 16-level grayscale.
2. One is pulse width modulation. The content of the serial transmission of the scanning board is not the switching signal of each LED but an 8-bit binary gray value. Each LED has its own PWM to control the lighting time. In this way, in a cycle of repeated lighting, each pixel only needs 4 pulses under 16-level grayscale, and only 8 pulses under 256-level grayscale, which greatly reduces the serial transmission frequency. With this method of decentralized control of LED grayscale, 256-level grayscale control can be easily realized.