Grayscale, also known as mid-tone (Half-tone), mainly for the transmission of pictures, respectively, 16, 32, 64 three ways, it uses the matrix approach to the file pixel processing 16,32,64 Level, so that the transmission of pictures more clearly. Whether it is monochrome, two-color, three-color screen, to display images or animation need to constitute the pixels of each LED light gray scale adjustment, the adjustment of the fine degree is what we usually call the gray level.
There are two ways to control the LED gray scale: one is to change the flow of current, one is the pulse width modulation. 1. Change the current flowing through the LED. General LED tube allows continuous operating current in 20 mA or so, in addition to red LED saturation phenomenon, the other LED gray scale is basically proportional to the current flowing; another method is to use the human eye's visual inertia, with pulse width Modulation method to achieve gray-scale control, that is, periodically change the width of the optical pulse (that is, duty cycle), as long as the repetition of the light cycle is short enough (that is, the refresh rate is high enough), the human eye does not feel the luminous pixels Jitter. As the pulse width modulation is more suitable for digital control, so in the general use of microcomputer to provide LED display content today, almost all of the LED screen are using pulse width modulation to control the gray level. LED control system is usually composed of the main control box, scanning plate and display control device three parts.
The main control box from the computer's graphics card to obtain a screen pixel color brightness data, and then re-assigned to a number of scanning panels, each scanning board is responsible for controlling the LED display on a number of rows (columns), and each row ) On the LED display and control signals are transmitted in a serial manner.